mirror of
https://github.com/torvalds/linux.git
synced 2026-10-07 11:06:03 +02:00
ed3b875bea
Everything:
Total patches: 501
Reviews/patch: 1.66
Reviewed rate: 70%
Excluding DAMON:
Total patches: 356
Reviews/patch: 2.26
Reviewed rate: 90%
Excluding DAMON and selftests:
Total patches: 329
Reviews/patch: 2.31
Reviewed rate: 92%
Excluding DAMON, selftests and maple_tree:
Total patches: 328
Reviews/patch: 2.31
Reviewed rate: 92%
Summary of patch series in this merge:
- The 2 patch series "mm: drop "sub" prefix from various places" from
Dev Jain implements some page->folio conversion and a naming cleanup.
- The 2 patch series "mm/kasan: remove redundant initialization for
kasan_flag_write_only" from Igor Putko provides some KASAN cleanup work.
- The 2 patch series "mm/filemap: reduce unnecessary xarray lookups"
from Chi Zhiling provides a small speedup in the pagecaache read code.
- The 4 patch series "mm/percpu: Fix possible NOFS/NOIO reclaim
recursion" from Kaitao Cheng improves a few things in the vmalloc code -
mainly the avoidance of GFP_KERNEL allocations when the caller asked for
GFP_NOFS or GFP_NOIO.
- The 3 patch series "mm/kmemleak: avoid soft lockup when scanning task
stacks" from Breno Leitao avoids a soft lockup watchdog trigger from the
kmemleak scanning code in extreme situations.
- The 6 patch series "mm/page_owner: misc cleanups" from Ye Liu is a
collection of unrelated cleanups to the page_owner code. For some
reason lots of people have been working on the page_owner code this
cycle.
- The 4 patch series "mm: convert to walk_page_range_vma() to eliminate
find_vma()" from Kefeng Wang simplifies and accelerates the page walking
library function.
- The 3 patch series "mm/migrate: preparatory cleanups for batch copy
and offload" from Shivank Garg implements cleanups in the migration
code.
- The 4 patch series "mm/page_owner: add per-fd filter infrastructure
for print_mode and NUMA filtering" from Zhen Ni provides per-fd
filtering to page_owner in order to reduce the sometimes vast amount of
output it can produce.
- The 19 patch series "mm: Refactor bootmem gigantic hugepage
allocation" from Muchun Song is a "set of fixes and preparatory cleanups
around bootmem HugeTLB handling, sparse initialization ordering, and
related vmemmap setup".
- The 4 patch series "mm/zsmalloc: reduce lock contention in zs_free()"
from Wenchao Hao reduces lock contention in zs_free(), which dominates
the unmap path under memory pressure on Android (LMK kills) and on x86
servers running zswap-heavy workloads. Up to 1.83x improvement in
microbenchmarking.
- The 2 patch series "move alloc_tag.c file under mm/" from Suren
Baghdasaryan does that.
- The 6 patch series "samples/damon: handle damon_{start,stop}()
failures" from SJ Park fixes improper handling of damon_start(),
damon_stop(), and damon_call() failures across DAMON sample modules to
prevent potential memory leaks, operation disruptions and use-after-free
bugs.
- The 11 patch series "mm/damon/sysfs: kobject_del() directories that
users can create/remove" from SJ Park resolves an issue where delayed
sysfs directory removal under CONFIG_DEBUG_KOBJECT_RELEASE causes
creation failures due to duplicate directory names by adding missing
kobject_del() calls before creating new directories.
- The 3 patch series "mm: cleanup clear_not_present_full_ptes()" from
David Hildenbrand cleans up the core pte handling code.
- The 3 patch series "selftests/damon: misc fixes for test bugs" from
Kunwu Chan fixes several bugs in the DAMON selftests.
- The 2 patch series "selftests/damon: fix memcg_path staging handling"
from Cheng Nie fixes a bug in _damon_sysfs.py for damos_filter
memcg_path setup, and adds a test case for it in sysfs.py.
- The 2 patch series "selftests/damon: test kdamond refresh_ms" from
Ruslan Valiyev introduces selftest coverage for DAMON's refresh_ms sysfs
feature by updating the test control module and verifying that scheme
stats update automatically without manual intervention.
- The 5 patch series "mm/damon: five misc fixups" from Akinobu Mita
contains miscellaneous DAMON fixups.
- The 2 patch series "mm/damon/core: detect internal variation above
max_nr_regions/2" from Jiayuan Chen fixes DAMON's region splitting
behavior when region counts exceed half the maximum budget by
dynamically scaling down the split fraction as the limit approaches,
preventing large regions from staying un-split, and adds corresponding
KUnit test coverage.
- The 6 patch series "mm: preparatory patches for PMD level swap
entries" from Usama Arif refactors and cleans up PMD softleaf helpers,
call sites, and architecture flags to lay the groundwork for a follow-up
series that introduces PMD page table swap entries.
- The 11 patch series "mm/damon: update, optimize, and clean up doc,
tests, and code" from SJ Park updates DAMON design and ABI
documentation, expands unit and selftest coverage, optimizes
damon_commit_target_regions(), and cleans up recently added sysfs
interface code for better readability.
- The 2 patch series "mm/vmpressure: reduce CPU, memory and code
overhead on cgroup v2" from Usama Arif optimizes vmpressure() by
skipping unnecessary work on cgroup v2 for userspace event notifications
and refactors v1-only eventfd handling into mm/memcontrol-v1.c to reduce
memory overhead and code complexity.
- The 10 patch series "selftests/mm: refactor pkey helpers and fix mmap
error handling" from Hongfu Li refactors pkeys shared tracing and
assertion helpers into a common file, unifies protection key selftests
to use consistent diagnostic logging and assertions, and enforces
standardized MAP_FAILED return checks for mmap() calls across the tests.
- The 18 patch series "mm/damon: optimize out nr_accesses_bp" from SJ
Park replaces the error-prone, continuously updated nr_accesses_bp field
in damon_region with an on-demand moving sum function
(damon_nr_accesses_mvsum()), reducing structure memory overhead and
avoiding state corruption bugs.
- The 6 patch series "Open HugeTLB allocation routine for more generic
use" from Ackerley Tng decouples HugeTLB folio allocation from VMA
dependencies by introducing hugetlb_alloc_folio(), enabling subsystems
like guest_memfd to allocate HugeTLB folios without standard VMA
reservations or pseudo-VMAs.
- The 3 patch series "mm/damon: provide pseudo moving sum probe_hits"
from SJ Park integrates DAMON's probe_hits attribute counter into the
pseudo moving sum infrastructure, enabling real-time, online monitoring
without waiting for full aggregation intervals.
- The 18 patch series "mm: Some cleanups for page allocator APIs" from
Brendan Jackman simplifies and refactors the page allocator entry points
and flags by unifying allocation paths, adding internal alloc_flags
arguments, and eliminating redundant __ prefixed alloc_pages variants.
- The 5 patch series "Fix incorrect access of hugetlb pte entries" from
Dev Jain enforces the consistent use of huge_ptep_get() instead of
ptep_get() for HugeTLB entries and fixes an unaligned address issue in
arm64's huge_ptep_get() implementation.
- The 8 patch series "mm/damon: validate all parameters in the core"
from SJ Park consolidates parameter validation into the DAMON core
specifically within damon_start() and damon_commit_ctx() to centralize
error checking, eliminate caller-side redundant checks and to improve
maintenance efficiency.
- The 3 patch series "tools/mm/page_owner_sort: fix filtering and
cleanup issues" from Yichong Chen renames is_need() to filter_record()
for clearer return semantics, fixes per-record allocation memory leaks
and bounds output copies in search_pattern() to address an existing
buffer issue.
- The 4 patch series "memcg: bail out reclaim when memcg is dying" from
Jiayuan Chen mitigates a system-wide stall which occurs when a cgroup is
removed while one of its memory control files is doing synchronous
reclaim.
- The 5 patch series "mm/memory-failure: add panic option for
unrecoverable pages" from Breno Leitao introduces an opt-in
vm.panic_on_unrecoverable_memory_failure sysctl that immediately panics
the kernel on unrecoverable memory errors in kernel-owned pages to
preserve error context and prevent delayed, silent data corruption.
- The 11 patch series "mm/damon: refactor damon_{start,stop,commit}()
for simple error handling" from SJ Park refactors the DAMON core API
functions to guarantee that all contexts are fully stopped when
damon_start(), damon_stop(), or damon_commit() fail, eliminating the
need for complex and error-prone caller-side cleanup code.
- The 5 patch series "Keep tail page private zero at free and folio
split" from Zi Yan adds checks to ensure tail_page->private is zero when
freeing compound or high-order pages and when promoting tail pages
during large folio splits. By validating these fields at free and split
time, it allows the removal of redundant private field clearing inside
prep_compound_tail().
- The 4 patch series "mm: drop redundant lru_add_drain in anon folio
reuse paths" from Barry Song eliminates redundant lru_add_drain() calls
in wp_can_reuse_anon_folio() and do_swap_page() to reduce LRU lock
contention and system overhead.
By validating folio refcounts against the LRU cache before draining
and removing unnecessary drains in the swap path, it achieves up to a
30.5% reduction in drain calls during heavy swap workloads.
- The 3 patch series "mm: clean up folio LRU and swap declarations" from
Jianyue Wu reorganizes folio LRU and swap code by relocating
page-cluster state to mm/swap_state.c, renaming mm/swap.c to mm/folio.c,
and moving MM-internal reclaim declarations into mm/internal.h.
- The 15 patch series "userfaultfd: working set tracking for VM guest
memory" from Kiryl Shutsemau adds userfaultfd support for tracking the
working set of VM guest memory, so a VMM can identify hot pages and
reclaim cold ones to tiered or remote storage.
- The 10 patch series "mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE (Part
2)" from David Hildenbrand removes the remaining pieces of
CONFIG_HAVE_BOOTMEM_INFO_NODE, performing some smaller cleanups around
freeing of reserved vmemmap pages on the way.
- The 7 patch series "mm/damon: update probe hits for runtime parameter
commits" from SJ Park ensures that DAMON's probe_hits attribute counter
is properly updated when monitoring intervals are changed at runtime,
matching the behavior of nr_accesses. To achieve this, it refactors and
renames existing helper functions for shared use, applies the updates to
probe_hits, and handles edge cases in damon_probe_hits_mvsum() to
maintain measurement accuracy.
- The 3 patch series "KSM: performance optimizations for rmap_walk_ksm"
from xu xin resolves a severe KSM reverse-mapping performance bottleneck
where thousands of split VMAs sharing a single anon_vma cause extended
lock contention. By adding an interval-filtering check during the rmap
walk, it reduces worst-case anon_vma lock hold times from over 500ms
down to under 2ms, preventing application freezes and latency spikes
under memory pressure.
- The 3 patch series "mm: split a couple of headers from internal.h"
from Mike Rapoport splits declarations related to mm_init, memblock,
vmalloc and sparse into new headers.
- The 2 patch series "KSM: use linear_page_index in collect_procs_ksm()"
from xu xin applies the interval tree optimization from rmap_walk_ksm()
to collect_procs_ksm() to avoid iterating over non-matching VMAs during
KSM memory error handling. It hoists loop-invariant address
initialization and restricts the anon_vma_interval_tree_foreach walk to
a targeted page offset range, reducing redundant checks and improving
lookup efficiency.
- The 3 patch series "selftests/mm: avoid false failures in hugetlb and
KSM tests" from Sayali Patil fixes issues in the hugetlb and KSM MM
selftest categories that can report failures when the prerequisites for
the tests are not satisfied.
- The 19 patch series "mm/damon: introduce data attributes only
monitoring" from SJ Park introduces attribute-weighted region management
in DAMON, allowing users to prioritize specific data attributes (such as
page sizes or cgroups) over or instead of access monitoring.
By assigning weights to attribute probes, DAMON can completely disable
access tracking and adjust monitoring regions based on weighted
probe-hit counters to optimize monitoring quality for attribute-focused
workloads.
- The 8 patch series "mm/hmm: Add mmap lock-drop support for
userfaultfd-backed mappings" from Stanislav Kinsburskii extends
hmm_range_fault() to support userfaultfd-backed regions by allowing the
mmap lock to be dropped during fault handling via a new
hmm_range_fault_locked() helper.
By accepting a locked pointer and signaling retry status when lock
release occurs, it enables page fault resolution in userfaultfd regions
while preserving backward compatibility for existing callers.
- The 33 patch series "mm: make VMA page offset handling more
consistent" from Lorenzo Stoakes cleans up and standardizes how
vma->vm_pgoff is accessed and manipulated across file-backed and
anonymous mappings in the kernel.
It introduces dedicated helper functions such as vma_start_pgoff(),
vma_end_pgoff(), vma_set_pgoff() and linear_page_delta() while renaming
rmap interval tree helpers to better reflect their functionality.
These changes establish a cleaner foundation for future work that will
unify virtual page offset indexing for all anonymous and CoW'd folios.
- The 3 patch series "mm: handle device-private PMDs in walk callbacks"
from Usama Arif addresses kernel panics and state corruption caused by
MM walk callbacks reaching non-present device-private PMD swap entries
created during HMM migrations.
It ensures that functions which acquire pmd_trans_huge_lock() properly
recognize device-private PMDs instead of assuming a present THP or a
standard migration entry.
- The 5 patch series "mm/rmap: Refactor try_to_unmap_one" from Dev Jain
refactors try_to_unmap_one by modularizing Hugetlb, anonymous-lazyfree,
and anonymous-swapbacked logic into dedicated functions, laying the
structural groundwork for batched anonymous large folio unmapping.
- The 4 patch series "Docs/ABI/damon: sysfs ABI document fixes and
additions" from Song Hu fixes typos and fills in missing entries in the
DAMON sysfs ABI document.
- The 10 patch series "dax/kmem: atomic whole-device hotplug via sysfs"
from Gregory Price introduces an atomic sysfs state attribute and
supporting DAX/MM infrastructure to prevent userland races when
offlining and removing entire memory regions.
By adding an unplugged state alongside standard online modes, it
enables whole-device atomic hotplug control while preserving backward
compatibility.
- The 13 patch series "mm: convert more vm_flags_t users to vma_flags_t"
from Lorenzo Stoakes continues transitioning the kernel from the
deprecated vm_flags_t type to vma_flags_t across core memory management
infrastructure.
It replaces legacy type usage in core functions such as do_mmap(),
unmapped area allocation, mm->def_vma_flags, and VMA operations like
mlock, mprotect, and mremap.
- The 2 patch series "Two small patches to clean up mm/mm_slot.h" from
xu xin refactors mm_slot.h by introducing mm_slot_remove() to unify
duplicate slot deletion sequences in khugepaged and KSM. It also adds
code documentation explaining why mm_slot_lookup and mm_slot_insert must
remain as preprocessor macros rather than static inline functions.
- The 10 patch series "mm/damon/core: hide core-private struct fields"
from SJ Park cleans up DAMON core structures by consistently marking
internal-only fields with private: comment tags to prevent improper
direct access from outer layers.
It enforces encapsulation across core structures including
damon_region, damon_target, and damon_ctx and updates DAMON_SYSFS to
interact through approved access APIs instead of exposing raw struct
members.
- The 6 patch series "mm/damon: unurgent fixes for infinite loop, NULL
de-ref and races" from SJ Park addresses potential infinite loops, NULL
dereferences, and race conditions identified in DAMON.
It fixes an infinite loop triggered by extreme user configurations, a
NULL pointer dereference within unit tests and minor monitoring
accuracy degradation caused by subtle runtime races.
- The 2 patch series "mm/page_alloc: fixes for free_pages_nolock() on
RT/UP" from Brendan Jackman fixes an NMI safety flaw in
__free_frozen_pages() where freeing pages on non-SMP or PREEMPT_RT
kernels can bypass can_spin_trylock() checks via non-PCP or isolated
migration paths.
It also resolves potential kernel crashes and privilege escalation
risks triggered when BPF tracing runs in NMI context alongside memory
hotplug or large allocation frees.
- The 4 patch series "mm/page_alloc: couple of followups for recent
cleanups" from Brendan Jackman cleans up and updates page allocator
nomenclature, documentation, and debug assertions.
It aligns internal FPI_ flags with the public "nolock" naming
convention, removes outdated internal implementation details from
high-level page allocator comments, and eliminates obsolete VM_BUG_ON()
assertions in allocation paths.
- The 3 patch series "mm/mseal: further cleanups" from Lorenzo Stoakes
refactors and simplifies the mseal implementation by clarifying API
boundaries and removing unnecessary code complexity.
It replaces generic do_mseal() usage outside the syscall with a
dedicated mseal_mmap_page_zero() helper for MMAP_PAGE_ZERO, eliminates
mm_struct parameters to enforce that sealing applies only to
current->mm, and streamlines overall logic and comments with no
functional changes intended.
- The 4 patch series "mm/vmscan: fix swappiness=max and clean up
per-node proactive reclaim" from Ridong Chen resolves reclaim behavior
bugs and cleans up function parameters across memory reclaim paths.
It fixes swappiness=max in both standard reclaim and MGLRU so
unswappable anonymous memory no longer falls back to evicting page
cache, ensures reclaim_store() returns accurate error codes instead of
collapsing all failures into -EAGAIN, and removes the obsolete gfp_mask
parameter from __node_reclaim().
- The 6 patch series "mm: mincore: misc cleanups" from Kefeng Wang
cleans up and simplifies the mincore code. Most importantly, it removes
the historical special behavior that always reports VM_PFNMAP pages as
non-resident.
- The 2 patch series "mm/huge_memory: drop dead split helper variants"
from Kiryl Shutsemau implements two trivial cleanups in the folio split
API.
- The 7 patch series "mm/damon: fix uninitialized DAMOS field and kunit
exec expectation bugs" from SJ Park resolves minor operational and
testing bugs in DAMON identified by Sashiko. It initializes the
damos->last_applied field to prevent occasional efficiency degradation
and fixes invalid memory accesses in DAMON KUnit tests during test
failure handling.
- The 3 patch series "cleanup for stable_page_flags()" from Jinjiang Tu
cleans up and refactors stable_page_flags() used by /proc/kpageflags
without altering functionality.
It uses BIT_ULL() to prevent shift-overflow warnings on 64-bit flag
bits, converts folio-specific flag checks to standard folio_test_*()
helpers, and removes redundant CONFIG_PAGE_IDLE_FLAG handling.
- The 3 patch series "Batch unmap of uffd-wp file folios" from Dev Jain
extends batched folio unmapping support to file folios within
userfaultfd write-protect (uffd-wp) VMAs by adding batching capabilities
to pte_install_uffd_wp_if_needed().
This removes special-case restrictions on uffd-wp VMAs in
try_to_unmap_one(), significantly simplifying the function's control
flow and complexity.
- The 3 patch series "mm/early_ioremap: clarify and clean up
early_ioremap_reset()" from Sang-Heon Jeon clarifies and cleans up the
architecture-specific usage of __late_set_fixmap() and
__late_clear_fixmap() after early_ioremap_reset().
It adds explicit documentation regarding when early_ioremap_reset()
must be called and removes redundant macro definitions and reset calls
in the RISC-V and ARM64 architectures.
- The 4 patch series "mm: fix reclaim storms in defrag_mode" from
Johannes Weiner addresses severe performance regressions, swap storms,
and spurious OOMs caused by vm.defrag_mode=1 under high memory pressure
in Meta production.
It updates the page allocator slowpath so non-movable allocation
requests actively trigger direct reclaim and direct compaction at
pageblock_order scale, allowing them to claim whole pageblocks rather
than spinning unproductively.
- The 2 patch series "zram: lockmap tweaks" from Sebastian Siewior
optimizes and fixes lockdep tracking for zram devices by consolidating
per-entry lockmaps and isolating lock classes across multiple instances.
It reduces memory overhead by replacing per-entry lockdep_map instances
with a single map per struct zram, and assigns a dynamic lock_class_key
to each instance to prevent false deadlock reports when different zram
devices are backed by distinct filesystems.
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Merge tag 'mm-stable-2026-08-18-18-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "mm: drop "sub" prefix from various places" (Dev Jain)
page->folio conversion and a naming cleanup
- "mm/kasan: remove redundant initialization for kasan_flag_write_only"
(Igor Putko)
KASAN cleanup work
- "mm/filemap: reduce unnecessary xarray lookups" (Chi Zhiling)
Small speedup in the pagecaache read code
- "mm/percpu: Fix possible NOFS/NOIO reclaim recursion" (Kaitao Cheng)
Improve the vmalloc code - mainly the avoidance of GFP_KERNEL
allocations when the caller asked for GFP_NOFS or GFP_NOIO
- "mm/kmemleak: avoid soft lockup when scanning task stacks" (Breno
Leitao)
Avoid a soft lockup watchdog trigger from the kmemleak scanning code
in extreme situations
- "mm/page_owner: misc cleanups" (Ye Liu)
Cleanups to the page_owner code. For some reason lots of people have
been working on the page_owner code this cycle.
- "mm: convert to walk_page_range_vma() to eliminate find_vma()"
(Kefeng Wang)
Simplify and accelerate the page walking library function
- "mm/migrate: preparatory cleanups for batch copy and offload"
(Shivank Garg)
Cleanups in the migration code
- "mm/page_owner: add per-fd filter infrastructure for print_mode and
NUMA filtering" (Zhen Ni)
Per-fd filtering to page_owner in order to reduce the sometimes vast
amount of output it can produce
- "mm: Refactor bootmem gigantic hugepage allocation" (Muchun Song)
Fixes and preparatory cleanups around bootmem HugeTLB handling,
sparse initialization ordering, and related vmemmap setup
- "mm/zsmalloc: reduce lock contention in zs_free()" (Wenchao Hao)
Reduce lock contention in zs_free(), which dominates the unmap path
under memory pressure on Android (LMK kills) and on x86 servers
running zswap-heavy workloads.
Up to 1.83x improvement in microbenchmarking.
- "move alloc_tag.c file under mm/" (Suren Baghdasaryan)
- "samples/damon: handle damon_{start,stop}() failures" (SJ Park)
Fix improper handling of damon_start(), damon_stop(), and
damon_call() failures across DAMON sample modules to prevent
potential memory leaks, operation disruptions and use-after-free
bugs
- "mm/damon/sysfs: kobject_del() directories that users can
create/remove" (SJ Park)
Fix delayed sysfs directory removal under DEBUG_KOBJECT_RELEASE
causeing creation failures due to duplicate directory names by adding
missing kobject_del() calls before creating new directories
- "mm: cleanup clear_not_present_full_ptes()" (David Hildenbrand)
Clean up the core pte handling code
- "selftests/damon: misc fixes for test bugs" (Kunwu Chan)
Fix several bugs in the DAMON selftests
- "selftests/damon: fix memcg_path staging handling" (Cheng Nie)
Fix a bug in _damon_sysfs.py for damos_filter memcg_path setup, and
add a test case for it in sysfs.py.
- "selftests/damon: test kdamond refresh_ms" (Ruslan Valiyev)
Selftest coverage for DAMON's refresh_ms sysfs feature by updating
the test control module and verifying that scheme stats update
automatically without manual intervention
- "mm/damon: five misc fixups" (Akinobu Mita)
Miscellaneous DAMON fixups.
- "mm/damon/core: detect internal variation above max_nr_regions/2"
(Jiayuan Chen)
Fix DAMON's region splitting behavior when region counts exceed half
the maximum budget by dynamically scaling down the split fraction as
the limit approaches, preventing large regions from staying un-split,
and add corresponding KUnit test coverage
- "mm: preparatory patches for PMD level swap entries" (Usama Arif)
Refactor and clean up PMD softleaf helpers, call sites, and
architecture flags to lay the groundwork for a follow-up series that
introduces PMD page table swap entries
- "mm/damon: update, optimize, and clean up doc, tests, and code" (SJ
Park)
Update DAMON design and ABI documentation, expands unit and selftest
coverage, optimize damon_commit_target_regions(), and clean up
recently added sysfs interface code for better readability
- "mm/vmpressure: reduce CPU, memory and code overhead on cgroup v2"
(Usama Arif)
Optimize vmpressure() by skipping unnecessary work on cgroup v2 for
userspace event notifications and refactor v1-only eventfd handling
into mm/memcontrol-v1.c to reduce memory overhead and code complexity
- "selftests/mm: refactor pkey helpers and fix mmap error handling"
(Hongfu Li)
Refactor pkeys shared tracing and assertion helpers into a common
file, unify protection key selftests to use consistent diagnostic
logging and assertions, and enforce standardized MAP_FAILED return
checks for mmap() calls across the tests
- "mm/damon: optimize out nr_accesses_bp" (SJ Park)
Replace the error-prone, continuously updated nr_accesses_bp field in
damon_region with an on-demand moving sum function, reducing
structure memory overhead and avoiding state corruption bugs
- "Open HugeTLB allocation routine for more generic use" (Ackerley Tng)
Decouple HugeTLB folio allocation from VMA dependencies by
introducing hugetlb_alloc_folio(), enabling subsystems like
guest_memfd to allocate HugeTLB folios without standard VMA
reservations or pseudo-VMAs
- "mm/damon: provide pseudo moving sum probe_hits" (SJ Park)
Integrate DAMON's probe_hits attribute counter into the pseudo moving
sum infrastructure, enabling real-time, online monitoring without
waiting for full aggregation intervals
- "mm: Some cleanups for page allocator APIs" (Brendan Jackman)
Simplify and refactor the page allocator entry points and flags by
unifying allocation paths, adding internal alloc_flags arguments, and
eliminating redundant __ prefixed alloc_pages variants.
- "Fix incorrect access of hugetlb pte entries" (Dev Jain)
Enforce the consistent use of huge_ptep_get() instead of ptep_get()
for HugeTLB entries and fixes an unaligned address issue in arm64's
huge_ptep_get() implementation
- "mm/damon: validate all parameters in the core" (SJ Park)
Consolidate parameter validation into the DAMON core specifically
within damon_start() and damon_commit_ctx() to centralize error
checking, eliminate caller-side redundant checks and to improve
maintenance efficiency
- "tools/mm/page_owner_sort: fix filtering and cleanup issues" (Yichong
Chen)
Rename is_need() to filter_record() for clearer return semantics, fix
per-record allocation memory leaks and bound output copies in
search_pattern() to address an existing buffer issue
- "memcg: bail out reclaim when memcg is dying" (Jiayuan Chen)
Mitigate a system-wide stall which occurs when a cgroup is removed
while one of its memory control files is doing synchronous reclaim
- "mm/memory-failure: add panic option for unrecoverable pages" (Breno
Leitao)
Introduce an opt-in vm.panic_on_unrecoverable_memory_failure sysctl
that immediately panics the kernel on unrecoverable memory errors in
kernel-owned pages to preserve error context and prevent delayed,
silent data corruption
- "mm/damon: refactor damon_{start,stop,commit}() for simple error
handling" (SJ Park)
Refactor the DAMON core API functions to guarantee that all contexts
are fully stopped when damon_start(), damon_stop(), or damon_commit()
fail, eliminating the need for complex and error-prone caller-side
cleanup code
- "Keep tail page private zero at free and folio split" (Zi Yan)
Add checks to ensure tail_page->private is zero when freeing compound
or high-order pages and when promoting tail pages during large folio
splits. By validating these fields at free and split time, it allows
the removal of redundant private field clearing inside
prep_compound_tail()
- "mm: drop redundant lru_add_drain in anon folio reuse paths" (Barry
Song)
Eliminate redundant lru_add_drain() calls in
wp_can_reuse_anon_folio() and do_swap_page() to reduce LRU lock
contention and system overhead
By validating folio refcounts against the LRU cache before draining
and removing unnecessary drains in the swap path, it achieves up to a
30.5% reduction in drain calls during heavy swap workloads
- "mm: clean up folio LRU and swap declarations" (Jianyue Wu)
Reorganize folio LRU and swap code by relocating page-cluster state
to mm/swap_state.c, renaming mm/swap.c to mm/folio.c, and moving
MM-internal reclaim declarations into mm/internal.h.
- "userfaultfd: working set tracking for VM guest memory" (Kiryl
Shutsemau)
Add userfaultfd support for tracking the working set of VM guest
memory, so a VMM can identify hot pages and reclaim cold ones to
tiered or remote storage
- "mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE (Part 2)" (David
Hildenbrand)
Remove the remaining pieces of CONFIG_HAVE_BOOTMEM_INFO_NODE,
performing some smaller cleanups around freeing of reserved vmemmap
pages on the way.
- "mm/damon: update probe hits for runtime parameter commits" (SJ Park)
Ensure that DAMON's probe_hits attribute counter is properly updated
when monitoring intervals are changed at runtime, matching the
behavior of nr_accesses. To achieve this, it refactors and renames
existing helper functions for shared use, applies the updates to
probe_hits, and handles edge cases in damon_probe_hits_mvsum() to
maintain measurement accuracy.
- "KSM: performance optimizations for rmap_walk_ksm" (xu xin)
Resolve a severe KSM reverse-mapping performance bottleneck where
thousands of split VMAs sharing a single anon_vma cause extended lock
contention.
By adding an interval-filtering check during the rmap walk, it
reduces worst-case anon_vma lock hold times from over 500ms down to
under 2ms, preventing application freezes and latency spikes under
memory pressure.
- "mm: split a couple of headers from internal.h" (Mike Rapoport)
Split declarations related to mm_init, memblock, vmalloc and sparse
into new headers
- "KSM: use linear_page_index in collect_procs_ksm()" (xu xin)
Apply the interval tree optimization from rmap_walk_ksm() to
collect_procs_ksm() to avoid iterating over non-matching VMAs during
KSM memory error handling.
It hoists loop-invariant address initialization and restricts the
anon_vma_interval_tree_foreach walk to a targeted page offset range,
reducing redundant checks and improving lookup efficiency.
- "selftests/mm: avoid false failures in hugetlb and KSM tests" (Sayali
Patil)
Fix issues in the hugetlb and KSM MM selftest categories that can
report failures when the prerequisites for the tests are not
satisfied
- "mm/damon: introduce data attributes only monitoring" (SJ Park)
Introduce attribute-weighted region management in DAMON, allowing
users to prioritize specific data attributes (such as page sizes or
cgroups) over or instead of access monitoring.
By assigning weights to attribute probes, DAMON can completely
disable access tracking and adjust monitoring regions based on
weighted probe-hit counters to optimize monitoring quality for
attribute-focused workloads.
- "mm/hmm: Add mmap lock-drop support for userfaultfd-backed mappings"
(Stanislav Kinsburskii)
Extend hmm_range_fault() to support userfaultfd-backed regions by
allowing the mmap lock to be dropped during fault handling via a new
hmm_range_fault_locked() helper.
By accepting a locked pointer and signaling retry status when lock
release occurs, it enables page fault resolution in userfaultfd
regions while preserving backward compatibility for existing callers.
- "mm: make VMA page offset handling more consistent" (Lorenzo Stoakes)
Clean up and standardize how vma->vm_pgoff is accessed and
manipulated across file-backed and anonymous mappings in the kernel
It introduces dedicated helper functions such as vma_start_pgoff(),
vma_end_pgoff(), vma_set_pgoff() and linear_page_delta() while
renaming rmap interval tree helpers to better reflect their
functionality.
These changes establish a cleaner foundation for future work that
will unify virtual page offset indexing for all anonymous and CoW'd
folios.
- "mm: handle device-private PMDs in walk callbacks" (Usama Arif)
Address kernel panics and state corruption caused by MM walk
callbacks reaching non-present device-private PMD swap entries
created during HMM migrations
It ensures that functions which acquire pmd_trans_huge_lock()
properly recognize device-private PMDs instead of assuming a present
THP or a standard migration entry.
- "mm/rmap: Refactor try_to_unmap_one" (Dev Jain)
Refactor try_to_unmap_one by modularizing Hugetlb,
anonymous-lazyfree, and anonymous-swapbacked logic into dedicated
functions, laying the structural groundwork for batched anonymous
large folio unmapping.
- "Docs/ABI/damon: sysfs ABI document fixes and additions" (Song Hu)
Fix typos and fills in missing entries in the DAMON sysfs ABI
document
- "dax/kmem: atomic whole-device hotplug via sysfs" (Gregory Price)
Introduce an atomic sysfs state attribute and supporting DAX/MM
infrastructure to prevent userland races when offlining and removing
entire memory regions
By adding an unplugged state alongside standard online modes, it
enables whole-device atomic hotplug control while preserving backward
compatibility.
- "mm: convert more vm_flags_t users to vma_flags_t" (Lorenzo Stoakes)
Continue transitioning the kernel from the deprecated vm_flags_t type
to vma_flags_t across core memory management infrastructure.
It replaces legacy type usage in core functions such as do_mmap(),
unmapped area allocation, mm->def_vma_flags, and VMA operations like
mlock, mprotect, and mremap.
- "Two small patches to clean up mm/mm_slot.h" (xu xin)
Refactor mm_slot.h by introducing mm_slot_remove() to unify duplicate
slot deletion sequences in khugepaged and KSM. It also adds code
documentation explaining why mm_slot_lookup and mm_slot_insert must
remain as preprocessor macros rather than static inline functions.
- "mm/damon/core: hide core-private struct fields" (SJ Park)
Clean up DAMON core structures by consistently marking internal-only
fields with private: comment tags to prevent improper direct access
from outer layers.
It enforces encapsulation across core structures including
damon_region, damon_target, and damon_ctx and updates DAMON_SYSFS to
interact through approved access APIs instead of exposing raw struct
members.
- "mm/damon: unurgent fixes for infinite loop, NULL de-ref and races"
(SJ Park)
Address potential infinite loops, NULL dereferences, and race
conditions identified in DAMON
It fixes an infinite loop triggered by extreme user configurations, a
NULL pointer dereference within unit tests and minor monitoring
accuracy degradation caused by subtle runtime races.
- "mm/page_alloc: fixes for free_pages_nolock() on RT/UP" (Brendan
Jackman)
Fix an NMI safety flaw in __free_frozen_pages() where freeing pages
on non-SMP or PREEMPT_RT kernels can bypass can_spin_trylock() checks
via non-PCP or isolated migration paths.
It also resolves potential kernel crashes and privilege escalation
risks triggered when BPF tracing runs in NMI context alongside memory
hotplug or large allocation frees.
- "mm/page_alloc: couple of followups for recent cleanups" (Brendan
Jackman)
Clean up and update page allocator nomenclature, documentation, and
debug assertions.
It aligns internal FPI_ flags with the public "nolock" naming
convention, removes outdated internal implementation details from
high-level page allocator comments, and eliminates obsolete
VM_BUG_ON() assertions in allocation paths.
- "mm/mseal: further cleanups" (Lorenzo Stoakes)
Refactor and simplify the mseal implementation by clarifying API
boundaries and removing unnecessary code complexity.
It replaces generic do_mseal() usage outside the syscall with a
dedicated mseal_mmap_page_zero() helper for MMAP_PAGE_ZERO,
eliminates mm_struct parameters to enforce that sealing applies only
to current->mm, and streamlines overall logic and comments with no
functional changes intended.
- "mm/vmscan: fix swappiness=max and clean up per-node proactive
reclaim" (Ridong Chen)
Resolve reclaim behavior bugs and clean up function parameters across
memory reclaim paths
It fixes swappiness=max in both standard reclaim and MGLRU so
unswappable anonymous memory no longer falls back to evicting page
cache, ensures reclaim_store() returns accurate error codes instead
of collapsing all failures into -EAGAIN, and removes the obsolete
gfp_mask parameter from __node_reclaim().
- "mm: mincore: misc cleanups" (Kefeng Wang)
Clean up and simplifies the mincore code. Most importantly, it
removes the historical special behavior that always reports VM_PFNMAP
pages as non-resident.
- "mm/huge_memory: drop dead split helper variants" (Kiryl Shutsemau)
Two trivial cleanups in the folio split API
- "mm/damon: fix uninitialized DAMOS field and kunit exec expectation
bugs" (SJ Park)
Resolve minor operational and testing bugs in DAMON identified by
Sashiko. It initializes the damos->last_applied field to prevent
occasional efficiency degradation and fixes invalid memory accesses
in DAMON KUnit tests during test failure handling.
- "cleanup for stable_page_flags()" (Jinjiang Tu)
Clean up and refactor stable_page_flags() used by /proc/kpageflags
without altering functionality.
It uses BIT_ULL() to prevent shift-overflow warnings on 64-bit flag
bits, converts folio-specific flag checks to standard folio_test_*()
helpers, and removes redundant CONFIG_PAGE_IDLE_FLAG handling.
- "Batch unmap of uffd-wp file folios" (Dev Jain)
Extend batched folio unmapping support to file folios within
userfaultfd write-protect (uffd-wp) VMAs by adding batching
capabilities to pte_install_uffd_wp_if_needed().
This removes special-case restrictions on uffd-wp VMAs in
try_to_unmap_one(), significantly simplifying the function's control
flow and complexity.
- "mm/early_ioremap: clarify and clean up early_ioremap_reset()"
(Sang-Heon Jeon)
Clarify and clean up the architecture-specific usage of
__late_set_fixmap() and __late_clear_fixmap() after
early_ioremap_reset()
It adds explicit documentation regarding when early_ioremap_reset()
must be called and removes redundant macro definitions and reset
calls in the RISC-V and ARM64 architectures.
- "mm: fix reclaim storms in defrag_mode" (Johannes Weiner)
Address severe performance regressions, swap storms, and spurious
OOMs caused by vm.defrag_mode=1 under high memory pressure in Meta
production
It updates the page allocator slowpath so non-movable allocation
requests actively trigger direct reclaim and direct compaction at
pageblock_order scale, allowing them to claim whole pageblocks rather
than spinning unproductively.
- "zram: lockmap tweaks" (Sebastian Siewior)
Optimize and fix lockdep tracking for zram devices by consolidating
per-entry lockmaps and isolate lock classes across multiple instances
This reduces memory overhead by replacing per-entry lockdep_map
instances with a single map per struct zram, and assigns a dynamic
lock_class_key to each instance to prevent false deadlock reports
when different zram devices are backed by distinct filesystems.
* tag 'mm-stable-2026-08-18-18-39' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (501 commits)
selftests/mm: thuge-gen: fix test_shmget() for PAGE_SIZE check
selftests/mm: unpoison pages in memory-failure teardown
mm/shmem: downgrade final i_blocks check in shmem_evict_inode() to pr_warn()
mm/khugepaged: replace mutex_lock/mutex_unlock usage with guard macro
mm/zsmalloc: fix release order of locks in zs_page_migrate()
Documentation: zram: remove sections numbering
ksm: stop iterating VMAs when ksm_test_exit returns true
mm: fold userfaultfd_rwp() to false without CONFIG_ARCH_HAS_PTE_PROTNONE
mm/migrate: report RCU-tasks quiescent states in migrate_pages_batch()
zram: use a custom key for each zram object
zram: move lockmap to be per-zram instead per table
selftests/mm: fix gup_longterm EINVAL error message
mm: page_alloc: fix non-movable reclaim storm in defrag_mode
mm: page_alloc: move capture_control to the page allocator
mm: compaction: support non-movable compaction for pageblock requests
mm: page_alloc: __GFP_FS lockdep annotation for direct compaction
hugetlb: evaluate subpool free state while locked
mm/damon: remove trailing semicolons after function definitions
mm/damon/ops-common: prevent migration fallback to non-target nodes
mm/damon: update outdated comment about DAMOS filter handling
...
2497 lines
105 KiB
ReStructuredText
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ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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====================
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The /proc Filesystem
|
|
====================
|
|
|
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===================== ======================================= ================
|
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/proc/sys Terrehon Bowden <terrehon@pacbell.net>, October 7 1999
|
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Bodo Bauer <bb@ricochet.net>
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2.4.x update Jorge Nerin <comandante@zaralinux.com> November 14 2000
|
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move /proc/sys Shen Feng <shen@cn.fujitsu.com> April 1 2009
|
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fixes/update part 1.1 Stefani Seibold <stefani@seibold.net> June 9 2009
|
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===================== ======================================= ================
|
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|
|
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.. Table of Contents
|
|
|
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0 Preface
|
|
0.1 Introduction/Credits
|
|
0.2 Legal Stuff
|
|
|
|
1 Collecting System Information
|
|
1.1 Process-Specific Subdirectories
|
|
1.2 Kernel data
|
|
1.3 Networking info in /proc/net
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|
1.4 SCSI info
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|
1.5 Parallel port info in /proc/parport
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|
1.6 TTY info in /proc/tty
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|
1.7 Miscellaneous kernel statistics in /proc/stat
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1.8 Ext4 file system parameters
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1.9 /proc/consoles - Shows registered system consoles
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|
|
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2 Modifying System Parameters
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|
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3 Per-Process Parameters
|
|
3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj - Adjust the oom-killer
|
|
score
|
|
3.2 /proc/<pid>/oom_score - Display current oom-killer score
|
|
3.3 /proc/<pid>/io - Display the IO accounting fields
|
|
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
|
|
3.5 /proc/<pid>/mountinfo - Information about mounts
|
|
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
|
|
3.7 /proc/<pid>/task/<tid>/children - Information about task children
|
|
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
|
|
3.9 /proc/<pid>/map_files - Information about memory mapped files
|
|
3.10 /proc/<pid>/timerslack_ns - Task timerslack value
|
|
3.11 /proc/<pid>/patch_state - Livepatch patch operation state
|
|
3.12 /proc/<pid>/arch_status - Task architecture specific information
|
|
3.13 /proc/<pid>/fd - List of symlinks to open files
|
|
3.14 /proc/<pid>/ksm_stat - Information about the process's ksm status.
|
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|
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4 Configuring procfs
|
|
4.1 Mount options
|
|
4.2 Mount restrictions
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|
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5 Filesystem behavior
|
|
|
|
Preface
|
|
=======
|
|
|
|
0.1 Introduction/Credits
|
|
------------------------
|
|
|
|
We'd like to thank Alan Cox, Rik van Riel, and Alexey Kuznetsov and a lot of
|
|
other people for help compiling this documentation. We'd also like to extend a
|
|
special thank you to Andi Kleen for documentation, which we relied on heavily
|
|
to create this document, as well as the additional information he provided.
|
|
Thanks to everybody else who contributed source or docs to the Linux kernel
|
|
and helped create a great piece of software... :)
|
|
|
|
The latest version of this document is available online at
|
|
https://www.kernel.org/doc/html/latest/filesystems/proc.html
|
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|
|
0.2 Legal Stuff
|
|
---------------
|
|
|
|
We don't guarantee the correctness of this document, and if you come to us
|
|
complaining about how you screwed up your system because of incorrect
|
|
documentation, we won't feel responsible...
|
|
|
|
Chapter 1: Collecting System Information
|
|
========================================
|
|
|
|
In This Chapter
|
|
---------------
|
|
* Investigating the properties of the pseudo file system /proc and its
|
|
ability to provide information on the running Linux system
|
|
* Examining /proc's structure
|
|
* Uncovering various information about the kernel and the processes running
|
|
on the system
|
|
|
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------------------------------------------------------------------------------
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|
|
The proc file system acts as an interface to internal data structures in the
|
|
kernel. It can be used to obtain information about the system and to change
|
|
certain kernel parameters at runtime (sysctl).
|
|
|
|
First, we'll take a look at the read-only parts of /proc. In Chapter 2, we
|
|
show you how you can use /proc/sys to change settings.
|
|
|
|
1.1 Process-Specific Subdirectories
|
|
-----------------------------------
|
|
|
|
The directory /proc contains (among other things) one subdirectory for each
|
|
process running on the system, which is named after the process ID (PID).
|
|
|
|
The link 'self' points to the process reading the file system. Each process
|
|
subdirectory has the entries listed in Table 1-1.
|
|
|
|
A process can read its own information from /proc/PID/* with no extra
|
|
permissions. When reading /proc/PID/* information for other processes, reading
|
|
process is required to have either CAP_SYS_PTRACE capability with
|
|
PTRACE_MODE_READ access permissions, or, alternatively, CAP_PERFMON
|
|
capability. This applies to all read-only information like `maps`, `environ`,
|
|
`pagemap`, etc. The only exception is `mem` file due to its read-write nature,
|
|
which requires CAP_SYS_PTRACE capabilities with more elevated
|
|
PTRACE_MODE_ATTACH permissions; CAP_PERFMON capability does not grant access
|
|
to /proc/PID/mem for other processes.
|
|
|
|
Note that an open file descriptor to /proc/<pid> or to any of its
|
|
contained files or subdirectories does not prevent <pid> from being reused
|
|
for some other process in the event that <pid> exits. Operations on
|
|
open /proc/<pid> file descriptors corresponding to dead processes
|
|
never act on any new process that the kernel may, through chance, have
|
|
also assigned the process ID <pid>. Instead, operations on these FDs
|
|
usually fail with ESRCH.
|
|
|
|
.. table:: Table 1-1: Process specific entries in /proc
|
|
|
|
============= ===============================================================
|
|
File Content
|
|
============= ===============================================================
|
|
clear_refs Clears page referenced bits shown in smaps output
|
|
cmdline Command line arguments
|
|
cpu Current and last cpu in which it was executed (2.4)(smp)
|
|
cwd Link to the current working directory
|
|
environ Values of environment variables
|
|
exe Link to the executable of this process
|
|
fd Directory, which contains all file descriptors
|
|
maps Memory maps to executables and library files (2.4)
|
|
mem Memory held by this process
|
|
root Link to the root directory of this process
|
|
stat Process status
|
|
statm Process memory status information
|
|
status Process status in human readable form
|
|
wchan Present with CONFIG_KALLSYMS=y: it shows the kernel function
|
|
symbol the task is blocked in - or "0" if not blocked.
|
|
pagemap Page table
|
|
stack Report full stack trace, enable via CONFIG_STACKTRACE
|
|
smaps An extension based on maps, showing the memory consumption of
|
|
each mapping and flags associated with it
|
|
smaps_rollup Accumulated smaps stats for all mappings of the process. This
|
|
can be derived from smaps, but is faster and more convenient
|
|
numa_maps An extension based on maps, showing the memory locality and
|
|
binding policy as well as mem usage (in pages) of each mapping.
|
|
============= ===============================================================
|
|
|
|
For example, to get the status information of a process, all you have to do is
|
|
read the file /proc/PID/status::
|
|
|
|
>cat /proc/self/status
|
|
Name: cat
|
|
State: R (running)
|
|
Tgid: 5452
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|
Pid: 5452
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PPid: 743
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|
TracerPid: 0 (2.4)
|
|
Uid: 501 501 501 501
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Gid: 100 100 100 100
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FDSize: 256
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Groups: 100 14 16
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Kthread: 0
|
|
VmPeak: 5004 kB
|
|
VmSize: 5004 kB
|
|
VmLck: 0 kB
|
|
VmHWM: 476 kB
|
|
VmRSS: 476 kB
|
|
RssAnon: 352 kB
|
|
RssFile: 120 kB
|
|
RssShmem: 4 kB
|
|
VmData: 156 kB
|
|
VmStk: 88 kB
|
|
VmExe: 68 kB
|
|
VmLib: 1412 kB
|
|
VmPTE: 20 kb
|
|
VmSwap: 0 kB
|
|
HugetlbPages: 0 kB
|
|
CoreDumping: 0
|
|
THP_enabled: 1
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Threads: 1
|
|
SigQ: 0/28578
|
|
SigPnd: 0000000000000000
|
|
ShdPnd: 0000000000000000
|
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SigBlk: 0000000000000000
|
|
SigIgn: 0000000000000000
|
|
SigCgt: 0000000000000000
|
|
CapInh: 00000000fffffeff
|
|
CapPrm: 0000000000000000
|
|
CapEff: 0000000000000000
|
|
CapBnd: ffffffffffffffff
|
|
CapAmb: 0000000000000000
|
|
NoNewPrivs: 0
|
|
Seccomp: 0
|
|
Speculation_Store_Bypass: thread vulnerable
|
|
SpeculationIndirectBranch: conditional enabled
|
|
voluntary_ctxt_switches: 0
|
|
nonvoluntary_ctxt_switches: 1
|
|
|
|
This shows you nearly the same information you would get if you viewed it with
|
|
the ps command. In fact, ps uses the proc file system to obtain its
|
|
information. But you get a more detailed view of the process by reading the
|
|
file /proc/PID/status. It fields are described in table 1-2.
|
|
|
|
The statm file contains more detailed information about the process
|
|
memory usage. Its seven fields are explained in Table 1-3. The stat file
|
|
contains detailed information about the process itself. Its fields are
|
|
explained in Table 1-4.
|
|
|
|
(for SMP CONFIG users)
|
|
|
|
For making accounting scalable, RSS related information are handled in an
|
|
asynchronous manner and the value may not be very precise. To see a precise
|
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snapshot of a moment, you can see /proc/<pid>/smaps file and scan page table.
|
|
It's slow but very precise.
|
|
|
|
.. table:: Table 1-2: Contents of the status fields (as of 4.19)
|
|
|
|
========================== ===================================================
|
|
Field Content
|
|
========================== ===================================================
|
|
Name filename of the executable
|
|
Umask file mode creation mask
|
|
State state (R is running, S is sleeping, D is sleeping
|
|
in an uninterruptible wait, Z is zombie,
|
|
T is traced or stopped)
|
|
Tgid thread group ID
|
|
Ngid NUMA group ID (0 if none)
|
|
Pid process id
|
|
PPid process id of the parent process
|
|
TracerPid PID of process tracing this process (0 if not, or
|
|
the tracer is outside of the current pid namespace)
|
|
Uid Real, effective, saved set, and file system UIDs
|
|
Gid Real, effective, saved set, and file system GIDs
|
|
FDSize number of file descriptor slots currently allocated
|
|
Groups supplementary group list
|
|
NStgid descendant namespace thread group ID hierarchy
|
|
NSpid descendant namespace process ID hierarchy
|
|
NSpgid descendant namespace process group ID hierarchy
|
|
NSsid descendant namespace session ID hierarchy
|
|
Kthread kernel thread flag, 1 is yes, 0 is no
|
|
VmPeak peak virtual memory size
|
|
VmSize total program size
|
|
VmLck locked memory size
|
|
VmPin pinned memory size
|
|
VmHWM peak resident set size ("high water mark")
|
|
VmRSS size of memory portions. It contains the three
|
|
following parts
|
|
(VmRSS = RssAnon + RssFile + RssShmem)
|
|
RssAnon size of resident anonymous memory
|
|
RssFile size of resident file mappings
|
|
RssShmem size of resident shmem memory (includes SysV shm,
|
|
mapping of tmpfs and shared anonymous mappings)
|
|
VmData size of private data segments
|
|
VmStk size of stack segments
|
|
VmExe size of text segment
|
|
VmLib size of shared library code
|
|
VmPTE size of page table entries
|
|
VmSwap amount of swap used by anonymous private data
|
|
(shmem swap usage is not included)
|
|
HugetlbPages size of hugetlb memory portions
|
|
CoreDumping process's memory is currently being dumped
|
|
(killing the process may lead to a corrupted core)
|
|
THP_enabled process is allowed to use THP (returns 0 when
|
|
PR_SET_THP_DISABLE is set on the process to disable
|
|
THP completely, not just partially)
|
|
Threads number of threads
|
|
SigQ number of signals queued/max. number for queue
|
|
SigPnd bitmap of pending signals for the thread
|
|
ShdPnd bitmap of shared pending signals for the process
|
|
SigBlk bitmap of blocked signals
|
|
SigIgn bitmap of ignored signals
|
|
SigCgt bitmap of caught signals
|
|
CapInh bitmap of inheritable capabilities
|
|
CapPrm bitmap of permitted capabilities
|
|
CapEff bitmap of effective capabilities
|
|
CapBnd bitmap of capabilities bounding set
|
|
CapAmb bitmap of ambient capabilities
|
|
NoNewPrivs no_new_privs, like prctl(PR_GET_NO_NEW_PRIV, ...)
|
|
Seccomp seccomp mode, like prctl(PR_GET_SECCOMP, ...)
|
|
Speculation_Store_Bypass speculative store bypass mitigation status
|
|
SpeculationIndirectBranch indirect branch speculation mode
|
|
Cpus_allowed mask of CPUs on which this process may run
|
|
Cpus_allowed_list Same as previous, but in "list format"
|
|
Mems_allowed mask of memory nodes allowed to this process
|
|
Mems_allowed_list Same as previous, but in "list format"
|
|
voluntary_ctxt_switches number of voluntary context switches
|
|
nonvoluntary_ctxt_switches number of non voluntary context switches
|
|
========================== ===================================================
|
|
|
|
|
|
.. table:: Table 1-3: Contents of the statm fields (as of 2.6.8-rc3)
|
|
|
|
======== =============================== ==============================
|
|
Field Content
|
|
======== =============================== ==============================
|
|
size total program size (pages) (same as VmSize in status)
|
|
resident size of memory portions (pages) (same as VmRSS in status)
|
|
shared number of pages that are shared (i.e. backed by a file, same
|
|
as RssFile+RssShmem in status)
|
|
trs number of pages that are 'code' (not including libs; broken,
|
|
includes data segment)
|
|
lrs number of pages of library (always 0 on 2.6)
|
|
drs number of pages of data/stack (including libs; broken,
|
|
includes library text)
|
|
dt number of dirty pages (always 0 on 2.6)
|
|
======== =============================== ==============================
|
|
|
|
|
|
.. table:: Table 1-4: Contents of the stat fields (as of 2.6.30-rc7)
|
|
|
|
============= ===============================================================
|
|
Field Content
|
|
============= ===============================================================
|
|
pid process id
|
|
tcomm filename of the executable
|
|
state state (R is running, S is sleeping, D is sleeping in an
|
|
uninterruptible wait, Z is zombie, T is traced or stopped)
|
|
ppid process id of the parent process
|
|
pgrp pgrp of the process
|
|
sid session id
|
|
tty_nr tty the process uses
|
|
tty_pgrp pgrp of the tty
|
|
flags task flags
|
|
min_flt number of minor faults
|
|
cmin_flt number of minor faults with child's
|
|
maj_flt number of major faults
|
|
cmaj_flt number of major faults with child's
|
|
utime user mode jiffies
|
|
stime kernel mode jiffies
|
|
cutime user mode jiffies with child's
|
|
cstime kernel mode jiffies with child's
|
|
priority priority level
|
|
nice nice level
|
|
num_threads number of threads
|
|
it_real_value (obsolete, always 0)
|
|
start_time time the process started after system boot
|
|
vsize virtual memory size
|
|
rss resident set memory size
|
|
rsslim current limit in bytes on the rss
|
|
start_code address above which program text can run
|
|
end_code address below which program text can run
|
|
start_stack address of the start of the main process stack
|
|
esp current value of ESP
|
|
eip current value of EIP
|
|
pending bitmap of pending signals
|
|
blocked bitmap of blocked signals
|
|
sigign bitmap of ignored signals
|
|
sigcatch bitmap of caught signals
|
|
0 (place holder, used to be the wchan address,
|
|
use /proc/PID/wchan instead)
|
|
0 (place holder)
|
|
0 (place holder)
|
|
exit_signal signal to send to parent thread on exit
|
|
task_cpu which CPU the task is scheduled on
|
|
rt_priority realtime priority
|
|
policy scheduling policy (man sched_setscheduler)
|
|
blkio_ticks time spent waiting for block IO
|
|
gtime guest time of the task in jiffies
|
|
cgtime guest time of the task children in jiffies
|
|
start_data address above which program data+bss is placed
|
|
end_data address below which program data+bss is placed
|
|
start_brk address above which program heap can be expanded with brk()
|
|
arg_start address above which program command line is placed
|
|
arg_end address below which program command line is placed
|
|
env_start address above which program environment is placed
|
|
env_end address below which program environment is placed
|
|
exit_code the thread's exit_code in the form reported by the waitpid
|
|
system call
|
|
============= ===============================================================
|
|
|
|
The /proc/PID/maps file contains the currently mapped memory regions and
|
|
their access permissions.
|
|
|
|
The format is::
|
|
|
|
address perms offset dev inode pathname
|
|
|
|
08048000-08049000 r-xp 00000000 03:00 8312 /opt/test
|
|
08049000-0804a000 rw-p 00001000 03:00 8312 /opt/test
|
|
0804a000-0806b000 rw-p 00000000 00:00 0 [heap]
|
|
a7cb1000-a7cb2000 ---p 00000000 00:00 0
|
|
a7cb2000-a7eb2000 rw-p 00000000 00:00 0
|
|
a7eb2000-a7eb3000 ---p 00000000 00:00 0
|
|
a7eb3000-a7ed5000 rw-p 00000000 00:00 0
|
|
a7ed5000-a8008000 r-xp 00000000 03:00 4222 /lib/libc.so.6
|
|
a8008000-a800a000 r--p 00133000 03:00 4222 /lib/libc.so.6
|
|
a800a000-a800b000 rw-p 00135000 03:00 4222 /lib/libc.so.6
|
|
a800b000-a800e000 rw-p 00000000 00:00 0
|
|
a800e000-a8022000 r-xp 00000000 03:00 14462 /lib/libpthread.so.0
|
|
a8022000-a8023000 r--p 00013000 03:00 14462 /lib/libpthread.so.0
|
|
a8023000-a8024000 rw-p 00014000 03:00 14462 /lib/libpthread.so.0
|
|
a8024000-a8027000 rw-p 00000000 00:00 0
|
|
a8027000-a8043000 r-xp 00000000 03:00 8317 /lib/ld-linux.so.2
|
|
a8043000-a8044000 r--p 0001b000 03:00 8317 /lib/ld-linux.so.2
|
|
a8044000-a8045000 rw-p 0001c000 03:00 8317 /lib/ld-linux.so.2
|
|
aff35000-aff4a000 rw-p 00000000 00:00 0 [stack]
|
|
ffffe000-fffff000 r-xp 00000000 00:00 0 [vdso]
|
|
|
|
where "address" is the address space in the process that it occupies, "perms"
|
|
is a set of permissions::
|
|
|
|
r = read
|
|
w = write
|
|
x = execute
|
|
s = shared
|
|
p = private (copy on write)
|
|
|
|
"offset" is the offset into the mapping, "dev" is the device (major:minor), and
|
|
"inode" is the inode on that device. 0 indicates that no inode is associated
|
|
with the memory region, as the case would be with BSS (uninitialized data).
|
|
The "pathname" shows the name associated file for this mapping. If the mapping
|
|
is not associated with a file:
|
|
|
|
=================== ===========================================
|
|
[heap] the heap of the program
|
|
[stack] the stack of the main process
|
|
[vdso] the "virtual dynamic shared object",
|
|
the kernel system call handler
|
|
[anon:<name>] a private anonymous mapping that has been
|
|
named by userspace
|
|
[anon_shmem:<name>] an anonymous shared memory mapping that has
|
|
been named by userspace
|
|
=================== ===========================================
|
|
|
|
or if empty, the mapping is anonymous.
|
|
|
|
Starting with 6.11 kernel, /proc/PID/maps provides an alternative
|
|
ioctl()-based API that gives ability to flexibly and efficiently query and
|
|
filter individual VMAs. This interface is binary and is meant for more
|
|
efficient and easy programmatic use. `struct procmap_query`, defined in
|
|
linux/fs.h UAPI header, serves as an input/output argument to the
|
|
`PROCMAP_QUERY` ioctl() command. See comments in linus/fs.h UAPI header for
|
|
details on query semantics, supported flags, data returned, and general API
|
|
usage information.
|
|
|
|
The /proc/PID/smaps is an extension based on maps, showing the memory
|
|
consumption for each of the process's mappings. For each mapping (aka Virtual
|
|
Memory Area, or VMA) there is a series of lines such as the following::
|
|
|
|
08048000-080bc000 r-xp 00000000 03:02 13130 /bin/bash
|
|
|
|
Size: 1084 kB
|
|
KernelPageSize: 4 kB
|
|
MMUPageSize: 4 kB
|
|
Rss: 892 kB
|
|
Pss: 374 kB
|
|
Pss_Dirty: 0 kB
|
|
Shared_Clean: 892 kB
|
|
Shared_Dirty: 0 kB
|
|
Private_Clean: 0 kB
|
|
Private_Dirty: 0 kB
|
|
Referenced: 892 kB
|
|
Anonymous: 0 kB
|
|
KSM: 0 kB
|
|
LazyFree: 0 kB
|
|
AnonHugePages: 0 kB
|
|
FilePmdMapped: 0 kB
|
|
ShmemPmdMapped: 0 kB
|
|
Shared_Hugetlb: 0 kB
|
|
Private_Hugetlb: 0 kB
|
|
Swap: 0 kB
|
|
SwapPss: 0 kB
|
|
Locked: 0 kB
|
|
THPeligible: 0
|
|
VmFlags: rd ex mr mw me dw
|
|
|
|
The first of these lines shows the same information as is displayed for
|
|
the mapping in /proc/PID/maps. Following lines show the size of the
|
|
mapping (size); the smallest possible page size allocated when backing a
|
|
VMA (KernelPageSize), which is the granularity in which VMA modifications
|
|
can be performed; the smallest possible page size that could be used by the
|
|
MMU (MMUPageSize) when backing a VMA; the amount of the mapping that is
|
|
currently resident in RAM (RSS); the process's proportional share of this
|
|
mapping (PSS); and the number of clean and dirty shared and private pages
|
|
in the mapping.
|
|
|
|
"KernelPageSize" always corresponds to "MMUPageSize", except when a larger
|
|
kernel page size is emulated on a system with a smaller page size used by the
|
|
MMU, which is the case for some PPC64 setups with hugetlb. Furthermore,
|
|
"KernelPageSize" and "MMUPageSize" always correspond to the smallest
|
|
possible granularity (fallback) that can be encountered in a VMA throughout
|
|
its lifetime. These values are not affected by Transparent Huge Pages
|
|
being in effect, or any usage of larger MMU page sizes (either through
|
|
architectural huge-page mappings or other explicit/implicit coalescing of
|
|
virtual ranges performed by the MMU). "AnonHugePages", "ShmemPmdMapped" and
|
|
"FilePmdMapped" provide insight into the usage of PMD-level architectural
|
|
huge-page mappings.
|
|
|
|
The "proportional set size" (PSS) of a process is the count of pages it has
|
|
in memory, where each page is divided by the number of processes sharing it.
|
|
So if a process has 1000 pages all to itself, and 1000 shared with one other
|
|
process, its PSS will be 1500. "Pss_Dirty" is the portion of PSS which
|
|
consists of dirty pages. ("Pss_Clean" is not included, but it can be
|
|
calculated by subtracting "Pss_Dirty" from "Pss".)
|
|
|
|
Traditionally, a page is accounted as "private" if it is mapped exactly once,
|
|
and a page is accounted as "shared" when mapped multiple times, even when
|
|
mapped in the same process multiple times. Note that this accounting is
|
|
independent of MAP_SHARED.
|
|
|
|
In some kernel configurations, the semantics of pages part of a larger
|
|
allocation (e.g., THP) can differ: a page is accounted as "private" if all
|
|
pages part of the corresponding large allocation are *certainly* mapped in the
|
|
same process, even if the page is mapped multiple times in that process. A
|
|
page is accounted as "shared" if any page of the larger allocation
|
|
is *maybe* mapped in a different process. In some cases, a large allocation
|
|
might be treated as "maybe mapped by multiple processes" even though this
|
|
is no longer the case.
|
|
|
|
Some kernel configurations do not track the precise number of times a page part
|
|
of a larger allocation is mapped. In this case, when calculating the PSS, the
|
|
average number of mappings per page in this larger allocation might be used
|
|
as an approximation for the number of mappings of a page. The PSS calculation
|
|
will be imprecise in this case.
|
|
|
|
"Referenced" indicates the amount of memory currently marked as referenced or
|
|
accessed.
|
|
|
|
"Anonymous" shows the amount of memory that does not belong to any file. Even
|
|
a mapping associated with a file may contain anonymous pages: when MAP_PRIVATE
|
|
and a page is modified, the file page is replaced by a private anonymous copy.
|
|
|
|
"KSM" reports how many of the pages are KSM pages. Note that KSM-placed zeropages
|
|
are not included, only actual KSM pages.
|
|
|
|
"LazyFree" shows the amount of memory which is marked by madvise(MADV_FREE).
|
|
The memory isn't freed immediately with madvise(). It's freed in memory
|
|
pressure if the memory is clean. Please note that the printed value might
|
|
be lower than the real value due to optimizations used in the current
|
|
implementation. If this is not desirable please file a bug report.
|
|
|
|
"AnonHugePages", "ShmemPmdMapped" and "FilePmdMapped" show the amount of
|
|
memory backed by Transparent Huge Pages that are currently mapped by
|
|
architectural huge-page mappings at the PMD level. "AnonHugePages"
|
|
corresponds to memory that does not belong to a file, "ShmemPmdMapped" to
|
|
shared memory (shmem/tmpfs) and "FilePmdMapped" to file-backed memory
|
|
(excluding shmem/tmpfs).
|
|
|
|
There are no dedicated entries for Transparent Huge Pages (or similar concepts)
|
|
that are not mapped by architectural huge-page mappings at the PMD level.
|
|
|
|
"Shared_Hugetlb" and "Private_Hugetlb" show the amounts of memory backed by
|
|
hugetlbfs page which is *not* counted in "RSS" or "PSS" field for historical
|
|
reasons. And these are not included in {Shared,Private}_{Clean,Dirty} field.
|
|
|
|
"Swap" shows how much would-be-anonymous memory is also used, but out on swap.
|
|
|
|
For shmem mappings, "Swap" includes also the size of the mapped (and not
|
|
replaced by copy-on-write) part of the underlying shmem object out on swap.
|
|
"SwapPss" shows proportional swap share of this mapping. Unlike "Swap", this
|
|
does not take into account swapped out page of underlying shmem objects.
|
|
"Locked" indicates whether the mapping is locked in memory or not.
|
|
|
|
"THPeligible" indicates whether the mapping is eligible for allocating
|
|
naturally aligned THP pages of any currently enabled size. 1 if true, 0
|
|
otherwise.
|
|
|
|
If both the kernel and the CPU support protection keys (pkeys),
|
|
"ProtectionKey" indicates the memory protection key associated with the
|
|
virtual memory area.
|
|
|
|
"VmFlags" field deserves a separate description. This member represents the
|
|
kernel flags associated with the particular virtual memory area in two letter
|
|
encoded manner. The codes are the following:
|
|
|
|
== =============================================================
|
|
rd readable
|
|
wr writeable
|
|
ex executable
|
|
sh shared
|
|
mr may read
|
|
mw may write
|
|
me may execute
|
|
ms may share
|
|
gd stack segment growns down
|
|
pf pure PFN range
|
|
lo pages are locked in memory
|
|
io memory mapped I/O area
|
|
sr sequential read advise provided
|
|
rr random read advise provided
|
|
dc do not copy area on fork
|
|
de do not expand area on remapping
|
|
ac area is accountable
|
|
nr swap space is not reserved for the area
|
|
ht area uses huge tlb pages
|
|
sf synchronous page fault
|
|
ar architecture specific flag
|
|
wf wipe on fork
|
|
dd do not include area into core dump
|
|
sd soft dirty flag
|
|
mm mixed map area
|
|
hg huge page advise flag
|
|
nh no huge page advise flag
|
|
mg mergeable advise flag
|
|
bt arm64 BTI guarded page
|
|
mt arm64 MTE allocation tags are enabled
|
|
um userfaultfd missing tracking
|
|
uw userfaultfd wr-protect tracking
|
|
ui userfaultfd minor fault
|
|
ur userfaultfd read-write-protect tracking
|
|
ss shadow/guarded control stack page
|
|
sl sealed
|
|
lf lock on fault pages
|
|
dp always lazily freeable mapping
|
|
gu maybe contains guard regions (if not set, definitely doesn't)
|
|
== =============================================================
|
|
|
|
Note that there is no guarantee that every flag and associated mnemonic will
|
|
be present in all further kernel releases. Things get changed, the flags may
|
|
be vanished or the reverse -- new added. Interpretation of their meaning
|
|
might change in future as well. So each consumer of these flags has to
|
|
follow each specific kernel version for the exact semantic.
|
|
|
|
This file is only present if the CONFIG_MMU kernel configuration option is
|
|
enabled.
|
|
|
|
Note: reading /proc/PID/maps or /proc/PID/smaps is inherently racy (consistent
|
|
output can be achieved only in the single read call).
|
|
|
|
This typically manifests when doing partial reads of these files while the
|
|
memory map is being modified. Despite the races, we do provide the following
|
|
guarantees:
|
|
|
|
1) The mapped addresses never go backwards, which implies no two
|
|
regions will ever overlap.
|
|
2) If there is something at a given vaddr during the entirety of the
|
|
life of the smaps/maps walk, there will be some output for it.
|
|
|
|
The /proc/PID/smaps_rollup file includes the same fields as /proc/PID/smaps,
|
|
but their values are the sums of the corresponding values for all mappings of
|
|
the process. Additionally, it contains these fields:
|
|
|
|
- Pss_Anon
|
|
- Pss_File
|
|
- Pss_Shmem
|
|
|
|
They represent the proportional shares of anonymous, file, and shmem pages, as
|
|
described for smaps above. These fields are omitted in smaps since each
|
|
mapping identifies the type (anon, file, or shmem) of all pages it contains.
|
|
Thus all information in smaps_rollup can be derived from smaps, but at a
|
|
significantly higher cost.
|
|
|
|
The /proc/PID/clear_refs is used to reset the PG_Referenced and ACCESSED/YOUNG
|
|
bits on both physical and virtual pages associated with a process, and the
|
|
soft-dirty bit on pte (see Documentation/admin-guide/mm/soft-dirty.rst
|
|
for details).
|
|
To clear the bits for all the pages associated with the process::
|
|
|
|
> echo 1 > /proc/PID/clear_refs
|
|
|
|
To clear the bits for the anonymous pages associated with the process::
|
|
|
|
> echo 2 > /proc/PID/clear_refs
|
|
|
|
To clear the bits for the file mapped pages associated with the process::
|
|
|
|
> echo 3 > /proc/PID/clear_refs
|
|
|
|
To clear the soft-dirty bit::
|
|
|
|
> echo 4 > /proc/PID/clear_refs
|
|
|
|
To reset the peak resident set size ("high water mark") to the process's
|
|
current value::
|
|
|
|
> echo 5 > /proc/PID/clear_refs
|
|
|
|
Any other value written to /proc/PID/clear_refs will have no effect.
|
|
|
|
The /proc/pid/pagemap gives the PFN, which can be used to find the pageflags
|
|
using /proc/kpageflags and number of times a page is mapped using
|
|
/proc/kpagecount. For detailed explanation, see
|
|
Documentation/admin-guide/mm/pagemap.rst.
|
|
|
|
The /proc/pid/numa_maps is an extension based on maps, showing the memory
|
|
locality and binding policy, as well as the memory usage (in pages) of
|
|
each mapping. The output follows a general format where mapping details get
|
|
summarized separated by blank spaces, one mapping per each file line::
|
|
|
|
address policy mapping details
|
|
|
|
00400000 default file=/usr/local/bin/app mapped=1 active=0 N3=1 kernelpagesize_kB=4
|
|
00600000 default file=/usr/local/bin/app anon=1 dirty=1 N3=1 kernelpagesize_kB=4
|
|
3206000000 default file=/lib64/ld-2.12.so mapped=26 mapmax=6 N0=24 N3=2 kernelpagesize_kB=4
|
|
320621f000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
|
|
3206220000 default file=/lib64/ld-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
|
|
3206221000 default anon=1 dirty=1 N3=1 kernelpagesize_kB=4
|
|
3206800000 default file=/lib64/libc-2.12.so mapped=59 mapmax=21 active=55 N0=41 N3=18 kernelpagesize_kB=4
|
|
320698b000 default file=/lib64/libc-2.12.so
|
|
3206b8a000 default file=/lib64/libc-2.12.so anon=2 dirty=2 N3=2 kernelpagesize_kB=4
|
|
3206b8e000 default file=/lib64/libc-2.12.so anon=1 dirty=1 N3=1 kernelpagesize_kB=4
|
|
3206b8f000 default anon=3 dirty=3 active=1 N3=3 kernelpagesize_kB=4
|
|
7f4dc10a2000 default anon=3 dirty=3 N3=3 kernelpagesize_kB=4
|
|
7f4dc10b4000 default anon=2 dirty=2 active=1 N3=2 kernelpagesize_kB=4
|
|
7f4dc1200000 default file=/anon_hugepage\040(deleted) huge anon=1 dirty=1 N3=1 kernelpagesize_kB=2048
|
|
7fff335f0000 default stack anon=3 dirty=3 N3=3 kernelpagesize_kB=4
|
|
7fff3369d000 default mapped=1 mapmax=35 active=0 N3=1 kernelpagesize_kB=4
|
|
|
|
Where:
|
|
|
|
"address" is the starting address for the mapping;
|
|
|
|
"policy" reports the NUMA memory policy set for the mapping (see Documentation/admin-guide/mm/numa_memory_policy.rst);
|
|
|
|
"mapping details" summarizes mapping data such as mapping type, page usage counters,
|
|
node locality page counters (N0 == node0, N1 == node1, ...) and the kernel page
|
|
size, in KB, that is backing the mapping up.
|
|
|
|
Note that some kernel configurations do not track the precise number of times
|
|
a page part of a larger allocation (e.g., THP) is mapped. In these
|
|
configurations, "mapmax" might corresponds to the average number of mappings
|
|
per page in such a larger allocation instead.
|
|
|
|
1.2 Kernel data
|
|
---------------
|
|
|
|
Similar to the process entries, the kernel data files give information about
|
|
the running kernel. The files used to obtain this information are contained in
|
|
/proc and are listed in Table 1-5. Not all of these will be present in your
|
|
system. It depends on the kernel configuration and the loaded modules, which
|
|
files are there, and which are missing.
|
|
|
|
.. table:: Table 1-5: Kernel info in /proc
|
|
|
|
============ ===============================================================
|
|
File Content
|
|
============ ===============================================================
|
|
allocinfo Memory allocations profiling information
|
|
apm Advanced power management info
|
|
bootconfig Kernel command line obtained from boot config,
|
|
and, if there were kernel parameters from the
|
|
boot loader, a "# Parameters from bootloader:"
|
|
line followed by a line containing those
|
|
parameters prefixed by "# ". (5.5)
|
|
buddyinfo Kernel memory allocator information (see text) (2.5)
|
|
bus Directory containing bus specific information
|
|
cmdline Kernel command line, both from bootloader and embedded
|
|
in the kernel image
|
|
cpuinfo Info about the CPU
|
|
devices Available devices (block and character)
|
|
dma Used DMA channels
|
|
filesystems Supported filesystems
|
|
driver Various drivers grouped here, currently rtc (2.4)
|
|
execdomains Execdomains, related to security (2.4)
|
|
fb Frame Buffer devices (2.4)
|
|
fs File system parameters, currently nfs/exports (2.4)
|
|
ide Directory containing info about the IDE subsystem
|
|
interrupts Interrupt usage
|
|
iomem Memory map (2.4)
|
|
ioports I/O port usage
|
|
irq Masks for irq to cpu affinity (2.4)(smp?)
|
|
isapnp ISA PnP (Plug&Play) Info (2.4)
|
|
kcore Kernel core image (can be ELF or A.OUT(deprecated in 2.4))
|
|
kmsg Kernel messages
|
|
ksyms Kernel symbol table
|
|
loadavg Load average of last 1, 5 & 15 minutes;
|
|
number of processes currently runnable (running or on ready queue);
|
|
total number of processes in system;
|
|
last pid created.
|
|
All fields are separated by one space except "number of
|
|
processes currently runnable" and "total number of processes
|
|
in system", which are separated by a slash ('/'). Example:
|
|
0.61 0.61 0.55 3/828 22084
|
|
locks Kernel locks
|
|
meminfo Memory info
|
|
misc Miscellaneous
|
|
modules List of loaded modules
|
|
mounts Mounted filesystems
|
|
net Networking info (see text)
|
|
pagetypeinfo Additional page allocator information (see text) (2.5)
|
|
partitions Table of partitions known to the system
|
|
pci Deprecated info of PCI bus (new way -> /proc/bus/pci/,
|
|
decoupled by lspci (2.4)
|
|
rtc Real time clock
|
|
scsi SCSI info (see text)
|
|
slabinfo Slab pool info
|
|
softirqs softirq usage
|
|
stat Overall statistics
|
|
swaps Swap space utilization
|
|
sys See chapter 2
|
|
sysvipc Info of SysVIPC Resources (msg, sem, shm) (2.4)
|
|
tty Info of tty drivers
|
|
uptime Wall clock since boot, combined idle time of all cpus
|
|
version Kernel version
|
|
video bttv info of video resources (2.4)
|
|
vmallocinfo Show vmalloced areas
|
|
============ ===============================================================
|
|
|
|
You can, for example, check which interrupts are currently in use and what
|
|
they are used for by looking in the file /proc/interrupts::
|
|
|
|
> cat /proc/interrupts
|
|
CPU0
|
|
0: 8728810 XT-PIC timer
|
|
1: 895 XT-PIC keyboard
|
|
2: 0 XT-PIC cascade
|
|
3: 531695 XT-PIC aha152x
|
|
4: 2014133 XT-PIC serial
|
|
5: 44401 XT-PIC pcnet_cs
|
|
8: 2 XT-PIC rtc
|
|
11: 8 XT-PIC i82365
|
|
12: 182918 XT-PIC PS/2 Mouse
|
|
13: 1 XT-PIC fpu
|
|
14: 1232265 XT-PIC ide0
|
|
15: 7 XT-PIC ide1
|
|
NMI: 0
|
|
|
|
In 2.4.* a couple of lines where added to this file LOC & ERR (this time is the
|
|
output of a SMP machine)::
|
|
|
|
> cat /proc/interrupts
|
|
|
|
CPU0 CPU1
|
|
0: 1243498 1214548 IO-APIC-edge timer
|
|
1: 8949 8958 IO-APIC-edge keyboard
|
|
2: 0 0 XT-PIC cascade
|
|
5: 11286 10161 IO-APIC-edge soundblaster
|
|
8: 1 0 IO-APIC-edge rtc
|
|
9: 27422 27407 IO-APIC-edge 3c503
|
|
12: 113645 113873 IO-APIC-edge PS/2 Mouse
|
|
13: 0 0 XT-PIC fpu
|
|
14: 22491 24012 IO-APIC-edge ide0
|
|
15: 2183 2415 IO-APIC-edge ide1
|
|
17: 30564 30414 IO-APIC-level eth0
|
|
18: 177 164 IO-APIC-level bttv
|
|
NMI: 2457961 2457959
|
|
LOC: 2457882 2457881
|
|
ERR: 2155
|
|
|
|
NMI is incremented in this case because every timer interrupt generates a NMI
|
|
(Non Maskable Interrupt) which is used by the NMI Watchdog to detect lockups.
|
|
|
|
LOC is the local interrupt counter of the internal APIC of every CPU.
|
|
|
|
ERR is incremented in the case of errors in the IO-APIC bus (the bus that
|
|
connects the CPUs in a SMP system. This means that an error has been detected,
|
|
the IO-APIC automatically retry the transmission, so it should not be a big
|
|
problem, but you should read the SMP-FAQ.
|
|
|
|
In 2.6.2* /proc/interrupts was expanded again. This time the goal was for
|
|
/proc/interrupts to display every IRQ vector in use by the system, not
|
|
just those considered 'most important'. The new vectors are:
|
|
|
|
THR
|
|
interrupt raised when a machine check threshold counter
|
|
(typically counting ECC corrected errors of memory or cache) exceeds
|
|
a configurable threshold. Only available on some systems.
|
|
|
|
TRM
|
|
a thermal event interrupt occurs when a temperature threshold
|
|
has been exceeded for the CPU. This interrupt may also be generated
|
|
when the temperature drops back to normal.
|
|
|
|
SPU
|
|
a spurious interrupt is some interrupt that was raised then lowered
|
|
by some IO device before it could be fully processed by the APIC. Hence
|
|
the APIC sees the interrupt but does not know what device it came from.
|
|
For this case the APIC will generate the interrupt with a IRQ vector
|
|
of 0xff. This might also be generated by chipset bugs.
|
|
|
|
RES, CAL, TLB
|
|
rescheduling, call and TLB flush interrupts are
|
|
sent from one CPU to another per the needs of the OS. Typically,
|
|
their statistics are used by kernel developers and interested users to
|
|
determine the occurrence of interrupts of the given type.
|
|
|
|
The above IRQ vectors are displayed only when relevant. For example,
|
|
the threshold vector does not exist on x86_64 platforms. Others are
|
|
suppressed when the system is a uniprocessor. As of this writing, only
|
|
i386 and x86_64 platforms support the new IRQ vector displays.
|
|
|
|
Of some interest is the introduction of the /proc/irq directory to 2.4.
|
|
It could be used to set IRQ to CPU affinity. This means that you can "hook" an
|
|
IRQ to only one CPU, or to exclude a CPU of handling IRQs. The contents of the
|
|
irq subdir is one subdir for each IRQ, and default_smp_affinity.
|
|
|
|
For example::
|
|
|
|
> ls /proc/irq/
|
|
0 10 12 14 16 18 2 4 6 8 default_smp_affinity
|
|
1 11 13 15 17 19 3 5 7 9
|
|
> ls /proc/irq/0/
|
|
smp_affinity
|
|
|
|
smp_affinity is a bitmask, in which you can specify which CPUs can handle the
|
|
IRQ. You can set it by doing::
|
|
|
|
> echo 1 > /proc/irq/10/smp_affinity
|
|
|
|
This means that only the first CPU will handle the IRQ, but you can also echo
|
|
5 which means that only the first and third CPU can handle the IRQ.
|
|
|
|
The contents of each smp_affinity file is the same by default::
|
|
|
|
> cat /proc/irq/0/smp_affinity
|
|
ffffffff
|
|
|
|
There is an alternate interface, smp_affinity_list which allows specifying
|
|
a CPU range instead of a bitmask::
|
|
|
|
> cat /proc/irq/0/smp_affinity_list
|
|
1024-1031
|
|
|
|
The default_smp_affinity mask applies to all non-active IRQs, which are the
|
|
IRQs which have not yet been allocated/activated, and hence which lack a
|
|
/proc/irq/[0-9]* directory.
|
|
|
|
The node file on an SMP system shows the node to which the device using the IRQ
|
|
reports itself as being attached. This hardware locality information does not
|
|
include information about any possible driver locality preference.
|
|
|
|
The way IRQs are routed is handled by the IO-APIC, and it's Round Robin
|
|
between all the CPUs which are allowed to handle it. As usual the kernel has
|
|
more info than you and does a better job than you, so the defaults are the
|
|
best choice for almost everyone. [Note this applies only to those IO-APIC's
|
|
that support "Round Robin" interrupt distribution.]
|
|
|
|
There are three more important subdirectories in /proc: net, scsi, and sys.
|
|
The general rule is that the contents, or even the existence of these
|
|
directories, depend on your kernel configuration. If SCSI is not enabled, the
|
|
directory scsi may not exist. The same is true with the net, which is there
|
|
only when networking support is present in the running kernel.
|
|
|
|
The slabinfo file gives information about memory usage at the slab level.
|
|
Linux uses slab pools for memory management above page level in version 2.2.
|
|
Commonly used objects have their own slab pool (such as network buffers,
|
|
directory cache, and so on).
|
|
|
|
::
|
|
|
|
> cat /proc/buddyinfo
|
|
|
|
Node 0, zone DMA 0 4 5 4 4 3 ...
|
|
Node 0, zone Normal 1 0 0 1 101 8 ...
|
|
Node 0, zone HighMem 2 0 0 1 1 0 ...
|
|
|
|
External fragmentation is a problem under some workloads, and buddyinfo is a
|
|
useful tool for helping diagnose these problems. Buddyinfo will give you a
|
|
clue as to how big an area you can safely allocate, or why a previous
|
|
allocation failed.
|
|
|
|
Each column represents the number of pages of a certain order which are
|
|
available. In this case, there are 0 chunks of 2^0*PAGE_SIZE available in
|
|
ZONE_DMA, 4 chunks of 2^1*PAGE_SIZE in ZONE_DMA, 101 chunks of 2^4*PAGE_SIZE
|
|
available in ZONE_NORMAL, etc...
|
|
|
|
More information relevant to external fragmentation can be found in
|
|
pagetypeinfo::
|
|
|
|
> cat /proc/pagetypeinfo
|
|
Page block order: 9
|
|
Pages per block: 512
|
|
|
|
Free pages count per migrate type at order 0 1 2 3 4 5 6 7 8 9 10
|
|
Node 0, zone DMA, type Unmovable 0 0 0 1 1 1 1 1 1 1 0
|
|
Node 0, zone DMA, type Reclaimable 0 0 0 0 0 0 0 0 0 0 0
|
|
Node 0, zone DMA, type Movable 1 1 2 1 2 1 1 0 1 0 2
|
|
Node 0, zone DMA, type Reserve 0 0 0 0 0 0 0 0 0 1 0
|
|
Node 0, zone DMA, type Isolate 0 0 0 0 0 0 0 0 0 0 0
|
|
Node 0, zone DMA32, type Unmovable 103 54 77 1 1 1 11 8 7 1 9
|
|
Node 0, zone DMA32, type Reclaimable 0 0 2 1 0 0 0 0 1 0 0
|
|
Node 0, zone DMA32, type Movable 169 152 113 91 77 54 39 13 6 1 452
|
|
Node 0, zone DMA32, type Reserve 1 2 2 2 2 0 1 1 1 1 0
|
|
Node 0, zone DMA32, type Isolate 0 0 0 0 0 0 0 0 0 0 0
|
|
|
|
Number of blocks type Unmovable Reclaimable Movable Reserve Isolate
|
|
Node 0, zone DMA 2 0 5 1 0
|
|
Node 0, zone DMA32 41 6 967 2 0
|
|
|
|
Fragmentation avoidance in the kernel works by grouping pages of different
|
|
migrate types into the same contiguous regions of memory called page blocks.
|
|
A page block is typically the size of the default hugepage size, e.g. 2MB on
|
|
X86-64. By keeping pages grouped based on their ability to move, the kernel
|
|
can reclaim pages within a page block to satisfy a high-order allocation.
|
|
|
|
The pagetypinfo begins with information on the size of a page block. It
|
|
then gives the same type of information as buddyinfo except broken down
|
|
by migrate-type and finishes with details on how many page blocks of each
|
|
type exist.
|
|
|
|
If min_free_kbytes has been tuned correctly (recommendations made by hugeadm
|
|
from libhugetlbfs https://github.com/libhugetlbfs/libhugetlbfs/), one can
|
|
make an estimate of the likely number of huge pages that can be allocated
|
|
at a given point in time. All the "Movable" blocks should be allocatable
|
|
unless memory has been mlock()'d. Some of the Reclaimable blocks should
|
|
also be allocatable although a lot of filesystem metadata may have to be
|
|
reclaimed to achieve this.
|
|
|
|
|
|
allocinfo
|
|
~~~~~~~~~
|
|
|
|
Provides information about memory allocations at all locations in the code
|
|
base. Each allocation in the code is identified by its source file, line
|
|
number, module (if originates from a loadable module) and the function calling
|
|
the allocation. The number of bytes allocated and number of calls at each
|
|
location are reported. The first line indicates the version of the file, the
|
|
second line is the header listing fields in the file.
|
|
If file version is 2.0 or higher then each line may contain additional
|
|
<key>:<value> pairs representing extra information about the call site.
|
|
For example if the counters are not accurate, the line will be appended with
|
|
"accurate:no" pair.
|
|
|
|
Supported markers in v2:
|
|
accurate:no
|
|
|
|
Absolute values of the counters in this line are not accurate
|
|
because of the failure to allocate memory to track some of the
|
|
allocations made at this location. Deltas in these counters are
|
|
accurate, therefore counters can be used to track allocation size
|
|
and count changes.
|
|
|
|
Example output.
|
|
|
|
::
|
|
|
|
> tail -n +3 /proc/allocinfo | sort -rn
|
|
127664128 31168 mm/page_ext.c:270 func:alloc_page_ext
|
|
56373248 4737 mm/slub.c:2259 func:alloc_slab_page
|
|
14880768 3633 mm/readahead.c:247 func:page_cache_ra_unbounded
|
|
14417920 3520 mm/mm_init.c:2530 func:alloc_large_system_hash
|
|
13377536 234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
|
|
11718656 2861 mm/filemap.c:1919 func:__filemap_get_folio
|
|
9192960 2800 kernel/fork.c:307 func:alloc_thread_stack_node
|
|
4206592 4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
|
|
4136960 1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
|
|
3940352 962 mm/memory.c:4214 func:alloc_anon_folio
|
|
2894464 22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
|
|
...
|
|
|
|
|
|
meminfo
|
|
~~~~~~~
|
|
|
|
Provides information about distribution and utilization of memory. This
|
|
varies by architecture and compile options. Some of the counters reported
|
|
here overlap. The memory reported by the non overlapping counters may not
|
|
add up to the overall memory usage and the difference for some workloads
|
|
can be substantial. In many cases there are other means to find out
|
|
additional memory using subsystem specific interfaces, for instance
|
|
/proc/net/sockstat for TCP memory allocations.
|
|
|
|
Example output. You may not have all of these fields.
|
|
|
|
::
|
|
|
|
> cat /proc/meminfo
|
|
|
|
MemTotal: 32858820 kB
|
|
MemFree: 21001236 kB
|
|
MemAvailable: 27214312 kB
|
|
Buffers: 581092 kB
|
|
Cached: 5587612 kB
|
|
SwapCached: 0 kB
|
|
Active: 3237152 kB
|
|
Inactive: 7586256 kB
|
|
Active(anon): 94064 kB
|
|
Inactive(anon): 4570616 kB
|
|
Active(file): 3143088 kB
|
|
Inactive(file): 3015640 kB
|
|
Unevictable: 0 kB
|
|
Mlocked: 0 kB
|
|
SwapTotal: 0 kB
|
|
SwapFree: 0 kB
|
|
Zswap: 1904 kB
|
|
Zswapped: 7792 kB
|
|
Dirty: 12 kB
|
|
Writeback: 0 kB
|
|
AnonPages: 4654780 kB
|
|
Mapped: 266244 kB
|
|
Shmem: 9976 kB
|
|
KReclaimable: 517708 kB
|
|
Slab: 660044 kB
|
|
SReclaimable: 517708 kB
|
|
SUnreclaim: 142336 kB
|
|
KernelStack: 11168 kB
|
|
PageTables: 20540 kB
|
|
SecPageTables: 0 kB
|
|
NFS_Unstable: 0 kB
|
|
Bounce: 0 kB
|
|
WritebackTmp: 0 kB
|
|
CommitLimit: 16429408 kB
|
|
Committed_AS: 7715148 kB
|
|
VmallocTotal: 34359738367 kB
|
|
VmallocUsed: 40444 kB
|
|
VmallocChunk: 0 kB
|
|
Percpu: 29312 kB
|
|
EarlyMemtestBad: 0 kB
|
|
HardwareCorrupted: 0 kB
|
|
AnonHugePages: 4149248 kB
|
|
ShmemHugePages: 0 kB
|
|
ShmemPmdMapped: 0 kB
|
|
FileHugePages: 0 kB
|
|
FilePmdMapped: 0 kB
|
|
CmaTotal: 0 kB
|
|
CmaFree: 0 kB
|
|
Unaccepted: 0 kB
|
|
Balloon: 0 kB
|
|
GPUActive: 0 kB
|
|
GPUReclaim: 0 kB
|
|
HugePages_Total: 0
|
|
HugePages_Free: 0
|
|
HugePages_Rsvd: 0
|
|
HugePages_Surp: 0
|
|
Hugepagesize: 2048 kB
|
|
Hugetlb: 0 kB
|
|
DirectMap4k: 401152 kB
|
|
DirectMap2M: 10008576 kB
|
|
DirectMap1G: 24117248 kB
|
|
|
|
MemTotal
|
|
Total usable RAM (i.e. physical RAM minus a few reserved
|
|
bits and the kernel binary code)
|
|
MemFree
|
|
Total free RAM. On highmem systems, the sum of LowFree+HighFree
|
|
MemAvailable
|
|
An estimate of how much memory is available for starting new
|
|
applications, without swapping. Calculated from MemFree,
|
|
SReclaimable, the size of the file LRU lists, and the low
|
|
watermarks in each zone.
|
|
The estimate takes into account that the system needs some
|
|
page cache to function well, and that not all reclaimable
|
|
slab will be reclaimable, due to items being in use. The
|
|
impact of those factors will vary from system to system.
|
|
Buffers
|
|
Relatively temporary storage for raw disk blocks
|
|
shouldn't get tremendously large (20MB or so)
|
|
Cached
|
|
In-memory cache for files read from the disk (the
|
|
pagecache) as well as tmpfs & shmem.
|
|
Doesn't include SwapCached.
|
|
SwapCached
|
|
Memory that once was swapped out, is swapped back in but
|
|
still also is in the swapfile (if memory is needed it
|
|
doesn't need to be swapped out AGAIN because it is already
|
|
in the swapfile. This saves I/O)
|
|
Active
|
|
Memory that has been used more recently and usually not
|
|
reclaimed unless absolutely necessary.
|
|
Inactive
|
|
Memory which has been less recently used. It is more
|
|
eligible to be reclaimed for other purposes
|
|
Unevictable
|
|
Memory allocated for userspace which cannot be reclaimed, such
|
|
as mlocked pages, ramfs backing pages, secret memfd pages etc.
|
|
Mlocked
|
|
Memory locked with mlock().
|
|
HighTotal, HighFree
|
|
Highmem is all memory above ~860MB of physical memory.
|
|
Highmem areas are for use by userspace programs, or
|
|
for the pagecache. The kernel must use tricks to access
|
|
this memory, making it slower to access than lowmem.
|
|
LowTotal, LowFree
|
|
Lowmem is memory which can be used for everything that
|
|
highmem can be used for, but it is also available for the
|
|
kernel's use for its own data structures. Among many
|
|
other things, it is where everything from the Slab is
|
|
allocated. Bad things happen when you're out of lowmem.
|
|
SwapTotal
|
|
total amount of swap space available
|
|
SwapFree
|
|
Memory which has been evicted from RAM, and is temporarily
|
|
on the disk
|
|
Zswap
|
|
Memory consumed by the zswap backend (compressed size)
|
|
Zswapped
|
|
Amount of anonymous memory stored in zswap (original size)
|
|
Dirty
|
|
Memory which is waiting to get written back to the disk
|
|
Writeback
|
|
Memory which is actively being written back to the disk
|
|
AnonPages
|
|
Non-file backed pages mapped into userspace page tables. Note that
|
|
some kernel configurations might consider all pages part of a
|
|
larger allocation (e.g., THP) as "mapped", as soon as a single
|
|
page is mapped.
|
|
Mapped
|
|
files which have been mmapped, such as libraries. Note that some
|
|
kernel configurations might consider all pages part of a larger
|
|
allocation (e.g., THP) as "mapped", as soon as a single page is
|
|
mapped.
|
|
Shmem
|
|
Total memory used by shared memory (shmem) and tmpfs
|
|
KReclaimable
|
|
Kernel allocations that the kernel will attempt to reclaim
|
|
under memory pressure. Includes SReclaimable (below), and other
|
|
direct allocations with a shrinker.
|
|
Slab
|
|
in-kernel data structures cache
|
|
SReclaimable
|
|
Part of Slab, that might be reclaimed, such as caches
|
|
SUnreclaim
|
|
Part of Slab, that cannot be reclaimed on memory pressure
|
|
KernelStack
|
|
Memory consumed by the kernel stacks of all tasks
|
|
PageTables
|
|
Memory consumed by userspace page tables
|
|
SecPageTables
|
|
Memory consumed by secondary page tables, this currently includes
|
|
KVM mmu and IOMMU allocations on x86 and arm64.
|
|
NFS_Unstable
|
|
Always zero. Previously counted pages which had been written to
|
|
the server, but has not been committed to stable storage.
|
|
Bounce
|
|
Always zero. Previously memory used for block device
|
|
"bounce buffers".
|
|
WritebackTmp
|
|
Always zero. Previously memory used by FUSE for temporary
|
|
writeback buffers.
|
|
CommitLimit
|
|
Based on the overcommit ratio ('vm.overcommit_ratio'),
|
|
this is the total amount of memory currently available to
|
|
be allocated on the system. This limit is only adhered to
|
|
if strict overcommit accounting is enabled (mode 2 in
|
|
'vm.overcommit_memory').
|
|
|
|
The CommitLimit is calculated with the following formula::
|
|
|
|
CommitLimit = ([total RAM pages] - [total huge TLB pages]) *
|
|
overcommit_ratio / 100 + [total swap pages]
|
|
|
|
For example, on a system with 1G of physical RAM and 7G
|
|
of swap with a `vm.overcommit_ratio` of 30 it would
|
|
yield a CommitLimit of 7.3G.
|
|
|
|
For more details, see the memory overcommit documentation
|
|
in mm/overcommit-accounting.
|
|
Committed_AS
|
|
The amount of memory presently allocated on the system.
|
|
The committed memory is a sum of all of the memory which
|
|
has been allocated by processes, even if it has not been
|
|
"used" by them as of yet. A process which malloc()'s 1G
|
|
of memory, but only touches 300M of it will show up as
|
|
using 1G. This 1G is memory which has been "committed" to
|
|
by the VM and can be used at any time by the allocating
|
|
application. With strict overcommit enabled on the system
|
|
(mode 2 in 'vm.overcommit_memory'), allocations which would
|
|
exceed the CommitLimit (detailed above) will not be permitted.
|
|
This is useful if one needs to guarantee that processes will
|
|
not fail due to lack of memory once that memory has been
|
|
successfully allocated.
|
|
VmallocTotal
|
|
total size of vmalloc virtual address space
|
|
VmallocUsed
|
|
amount of vmalloc area which is used
|
|
VmallocChunk
|
|
largest contiguous block of vmalloc area which is free
|
|
Percpu
|
|
Memory allocated to the percpu allocator used to back percpu
|
|
allocations. This stat excludes the cost of metadata.
|
|
EarlyMemtestBad
|
|
The amount of RAM/memory in kB, that was identified as corrupted
|
|
by early memtest. If memtest was not run, this field will not
|
|
be displayed at all. Size is never rounded down to 0 kB.
|
|
That means if 0 kB is reported, you can safely assume
|
|
there was at least one pass of memtest and none of the passes
|
|
found a single faulty byte of RAM.
|
|
HardwareCorrupted
|
|
The amount of RAM/memory in KB, the kernel identifies as
|
|
corrupted.
|
|
AnonHugePages
|
|
Non-file backed huge pages mapped into userspace page tables
|
|
ShmemHugePages
|
|
Memory used by shared memory (shmem) and tmpfs allocated
|
|
with huge pages
|
|
ShmemPmdMapped
|
|
Shared memory mapped into userspace with huge pages
|
|
FileHugePages
|
|
Memory used for filesystem data (page cache) allocated
|
|
with huge pages
|
|
FilePmdMapped
|
|
Page cache mapped into userspace with huge pages
|
|
CmaTotal
|
|
Memory reserved for the Contiguous Memory Allocator (CMA)
|
|
CmaFree
|
|
Free remaining memory in the CMA reserves
|
|
Unaccepted
|
|
Memory that has not been accepted by the guest
|
|
Balloon
|
|
Memory returned to Host by VM Balloon Drivers
|
|
GPUActive
|
|
System memory allocated to active GPU objects
|
|
GPUReclaim
|
|
System memory stored in GPU pools for reuse. This memory is not
|
|
counted in GPUActive. It is shrinker reclaimable memory kept in a reuse
|
|
pool because it has non-standard page table attributes, like WC or UC.
|
|
HugePages_Total, HugePages_Free, HugePages_Rsvd, HugePages_Surp, Hugepagesize, Hugetlb
|
|
See Documentation/admin-guide/mm/hugetlbpage.rst.
|
|
DirectMap4k, DirectMap2M, DirectMap1G
|
|
Breakdown of page table sizes used in the kernel's
|
|
identity mapping of RAM
|
|
|
|
vmallocinfo
|
|
~~~~~~~~~~~
|
|
|
|
Provides information about vmalloced/vmaped areas. One line per area,
|
|
containing the virtual address range of the area, size in bytes,
|
|
caller information of the creator, and optional information depending
|
|
on the kind of area:
|
|
|
|
========== ===================================================
|
|
pages=nr number of pages
|
|
phys=addr if a physical address was specified
|
|
ioremap I/O mapping (ioremap() and friends)
|
|
vmalloc vmalloc() area
|
|
vmap vmap()ed pages
|
|
user VM_USERMAP area
|
|
vpages buffer for pages pointers was vmalloced (huge area)
|
|
N<node>=nr (Only on NUMA kernels)
|
|
Number of pages allocated on memory node <node>
|
|
========== ===================================================
|
|
|
|
::
|
|
|
|
> cat /proc/vmallocinfo
|
|
0xffffc20000000000-0xffffc20000201000 2101248 alloc_large_system_hash+0x204 ...
|
|
/0x2c0 pages=512 vmalloc N0=128 N1=128 N2=128 N3=128
|
|
0xffffc20000201000-0xffffc20000302000 1052672 alloc_large_system_hash+0x204 ...
|
|
/0x2c0 pages=256 vmalloc N0=64 N1=64 N2=64 N3=64
|
|
0xffffc20000302000-0xffffc20000304000 8192 acpi_tb_verify_table+0x21/0x4f...
|
|
phys=7fee8000 ioremap
|
|
0xffffc20000304000-0xffffc20000307000 12288 acpi_tb_verify_table+0x21/0x4f...
|
|
phys=7fee7000 ioremap
|
|
0xffffc2000031d000-0xffffc2000031f000 8192 init_vdso_vars+0x112/0x210
|
|
0xffffc2000031f000-0xffffc2000032b000 49152 cramfs_uncompress_init+0x2e ...
|
|
/0x80 pages=11 vmalloc N0=3 N1=3 N2=2 N3=3
|
|
0xffffc2000033a000-0xffffc2000033d000 12288 sys_swapon+0x640/0xac0 ...
|
|
pages=2 vmalloc N1=2
|
|
0xffffc20000347000-0xffffc2000034c000 20480 xt_alloc_table_info+0xfe ...
|
|
/0x130 [x_tables] pages=4 vmalloc N0=4
|
|
0xffffffffa0000000-0xffffffffa000f000 61440 sys_init_module+0xc27/0x1d00 ...
|
|
pages=14 vmalloc N2=14
|
|
0xffffffffa000f000-0xffffffffa0014000 20480 sys_init_module+0xc27/0x1d00 ...
|
|
pages=4 vmalloc N1=4
|
|
0xffffffffa0014000-0xffffffffa0017000 12288 sys_init_module+0xc27/0x1d00 ...
|
|
pages=2 vmalloc N1=2
|
|
0xffffffffa0017000-0xffffffffa0022000 45056 sys_init_module+0xc27/0x1d00 ...
|
|
pages=10 vmalloc N0=10
|
|
|
|
|
|
softirqs
|
|
~~~~~~~~
|
|
|
|
Provides counts of softirq handlers serviced since boot time, for each CPU.
|
|
|
|
::
|
|
|
|
> cat /proc/softirqs
|
|
CPU0 CPU1 CPU2 CPU3
|
|
HI: 0 0 0 0
|
|
TIMER: 27166 27120 27097 27034
|
|
NET_TX: 0 0 0 17
|
|
NET_RX: 42 0 0 39
|
|
BLOCK: 0 0 107 1121
|
|
TASKLET: 0 0 0 290
|
|
SCHED: 27035 26983 26971 26746
|
|
HRTIMER: 0 0 0 0
|
|
RCU: 1678 1769 2178 2250
|
|
|
|
1.3 Networking info in /proc/net
|
|
--------------------------------
|
|
|
|
The subdirectory /proc/net follows the usual pattern. Table 1-8 shows the
|
|
additional values you get for IP version 6 if you configure the kernel to
|
|
support this. Table 1-9 lists the files and their meaning.
|
|
|
|
|
|
.. table:: Table 1-8: IPv6 info in /proc/net
|
|
|
|
========== =====================================================
|
|
File Content
|
|
========== =====================================================
|
|
udp6 UDP sockets (IPv6)
|
|
tcp6 TCP sockets (IPv6)
|
|
raw6 Raw device statistics (IPv6)
|
|
igmp6 IP multicast addresses, which this host joined (IPv6)
|
|
if_inet6 List of IPv6 interface addresses
|
|
ipv6_route Kernel routing table for IPv6
|
|
rt6_stats Global IPv6 routing tables statistics
|
|
sockstat6 Socket statistics (IPv6)
|
|
snmp6 Snmp data (IPv6)
|
|
========== =====================================================
|
|
|
|
.. table:: Table 1-9: Network info in /proc/net
|
|
|
|
============= ================================================================
|
|
File Content
|
|
============= ================================================================
|
|
arp Kernel ARP table
|
|
dev network devices with statistics
|
|
dev_mcast the Layer2 multicast groups a device is listening too
|
|
(interface index, label, number of references, number of bound
|
|
addresses).
|
|
dev_stat network device status
|
|
ip_fwchains Firewall chain linkage
|
|
ip_fwnames Firewall chain names
|
|
ip_masq Directory containing the masquerading tables
|
|
ip_masquerade Major masquerading table
|
|
netstat Network statistics
|
|
raw raw device statistics
|
|
route Kernel routing table
|
|
rpc Directory containing rpc info
|
|
rt_cache Routing cache
|
|
snmp SNMP data
|
|
sockstat Socket statistics
|
|
softnet_stat Per-CPU incoming packets queues statistics of online CPUs
|
|
tcp TCP sockets
|
|
udp UDP sockets
|
|
unix UNIX domain sockets
|
|
wireless Wireless interface data (Wavelan etc)
|
|
igmp IP multicast addresses, which this host joined
|
|
psched Global packet scheduler parameters.
|
|
netlink List of PF_NETLINK sockets
|
|
ip_mr_vifs List of multicast virtual interfaces
|
|
ip_mr_cache List of multicast routing cache
|
|
============= ================================================================
|
|
|
|
You can use this information to see which network devices are available in
|
|
your system and how much traffic was routed over those devices::
|
|
|
|
> cat /proc/net/dev
|
|
Inter-|Receive |[...
|
|
face |bytes packets errs drop fifo frame compressed multicast|[...
|
|
lo: 908188 5596 0 0 0 0 0 0 [...
|
|
ppp0:15475140 20721 410 0 0 410 0 0 [...
|
|
eth0: 614530 7085 0 0 0 0 0 1 [...
|
|
|
|
...] Transmit
|
|
...] bytes packets errs drop fifo colls carrier compressed
|
|
...] 908188 5596 0 0 0 0 0 0
|
|
...] 1375103 17405 0 0 0 0 0 0
|
|
...] 1703981 5535 0 0 0 3 0 0
|
|
|
|
In addition, each Channel Bond interface has its own directory. For
|
|
example, the bond0 device will have a directory called /proc/net/bond0/.
|
|
It will contain information that is specific to that bond, such as the
|
|
current slaves of the bond, the link status of the slaves, and how
|
|
many times the slaves link has failed.
|
|
|
|
1.4 SCSI info
|
|
-------------
|
|
|
|
If you have a SCSI or ATA host adapter in your system, you'll find a
|
|
subdirectory named after the driver for this adapter in /proc/scsi.
|
|
You'll also see a list of all recognized SCSI devices in /proc/scsi::
|
|
|
|
>cat /proc/scsi/scsi
|
|
Attached devices:
|
|
Host: scsi0 Channel: 00 Id: 00 Lun: 00
|
|
Vendor: IBM Model: DGHS09U Rev: 03E0
|
|
Type: Direct-Access ANSI SCSI revision: 03
|
|
Host: scsi0 Channel: 00 Id: 06 Lun: 00
|
|
Vendor: PIONEER Model: CD-ROM DR-U06S Rev: 1.04
|
|
Type: CD-ROM ANSI SCSI revision: 02
|
|
|
|
|
|
The directory named after the driver has one file for each adapter found in
|
|
the system. These files contain information about the controller, including
|
|
the used IRQ and the IO address range. The amount of information shown is
|
|
dependent on the adapter you use. The example shows the output for an Adaptec
|
|
AHA-2940 SCSI adapter::
|
|
|
|
> cat /proc/scsi/aic7xxx/0
|
|
|
|
Adaptec AIC7xxx driver version: 5.1.19/3.2.4
|
|
Compile Options:
|
|
TCQ Enabled By Default : Disabled
|
|
AIC7XXX_PROC_STATS : Disabled
|
|
AIC7XXX_RESET_DELAY : 5
|
|
Adapter Configuration:
|
|
SCSI Adapter: Adaptec AHA-294X Ultra SCSI host adapter
|
|
Ultra Wide Controller
|
|
PCI MMAPed I/O Base: 0xeb001000
|
|
Adapter SEEPROM Config: SEEPROM found and used.
|
|
Adaptec SCSI BIOS: Enabled
|
|
IRQ: 10
|
|
SCBs: Active 0, Max Active 2,
|
|
Allocated 15, HW 16, Page 255
|
|
Interrupts: 160328
|
|
BIOS Control Word: 0x18b6
|
|
Adapter Control Word: 0x005b
|
|
Extended Translation: Enabled
|
|
Disconnect Enable Flags: 0xffff
|
|
Ultra Enable Flags: 0x0001
|
|
Tag Queue Enable Flags: 0x0000
|
|
Ordered Queue Tag Flags: 0x0000
|
|
Default Tag Queue Depth: 8
|
|
Tagged Queue By Device array for aic7xxx host instance 0:
|
|
{255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255}
|
|
Actual queue depth per device for aic7xxx host instance 0:
|
|
{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1}
|
|
Statistics:
|
|
(scsi0:0:0:0)
|
|
Device using Wide/Sync transfers at 40.0 MByte/sec, offset 8
|
|
Transinfo settings: current(12/8/1/0), goal(12/8/1/0), user(12/15/1/0)
|
|
Total transfers 160151 (74577 reads and 85574 writes)
|
|
(scsi0:0:6:0)
|
|
Device using Narrow/Sync transfers at 5.0 MByte/sec, offset 15
|
|
Transinfo settings: current(50/15/0/0), goal(50/15/0/0), user(50/15/0/0)
|
|
Total transfers 0 (0 reads and 0 writes)
|
|
|
|
|
|
1.5 Parallel port info in /proc/parport
|
|
---------------------------------------
|
|
|
|
The directory /proc/parport contains information about the parallel ports of
|
|
your system. It has one subdirectory for each port, named after the port
|
|
number (0,1,2,...).
|
|
|
|
These directories contain the four files shown in Table 1-10.
|
|
|
|
|
|
.. table:: Table 1-10: Files in /proc/parport
|
|
|
|
========= ====================================================================
|
|
File Content
|
|
========= ====================================================================
|
|
autoprobe Any IEEE-1284 device ID information that has been acquired.
|
|
devices list of the device drivers using that port. A + will appear by the
|
|
name of the device currently using the port (it might not appear
|
|
against any).
|
|
hardware Parallel port's base address, IRQ line and DMA channel.
|
|
irq IRQ that parport is using for that port. This is in a separate
|
|
file to allow you to alter it by writing a new value in (IRQ
|
|
number or none).
|
|
========= ====================================================================
|
|
|
|
1.6 TTY info in /proc/tty
|
|
-------------------------
|
|
|
|
Information about the available and actually used tty's can be found in the
|
|
directory /proc/tty. You'll find entries for drivers and line disciplines in
|
|
this directory, as shown in Table 1-11.
|
|
|
|
|
|
.. table:: Table 1-11: Files in /proc/tty
|
|
|
|
============= ==============================================
|
|
File Content
|
|
============= ==============================================
|
|
drivers list of drivers and their usage
|
|
ldiscs registered line disciplines
|
|
driver/serial usage statistic and status of single tty lines
|
|
============= ==============================================
|
|
|
|
To see which tty's are currently in use, you can simply look into the file
|
|
/proc/tty/drivers::
|
|
|
|
> cat /proc/tty/drivers
|
|
pty_slave /dev/pts 136 0-255 pty:slave
|
|
pty_master /dev/ptm 128 0-255 pty:master
|
|
pty_slave /dev/ttyp 3 0-255 pty:slave
|
|
pty_master /dev/pty 2 0-255 pty:master
|
|
serial /dev/cua 5 64-67 serial:callout
|
|
serial /dev/ttyS 4 64-67 serial
|
|
/dev/tty0 /dev/tty0 4 0 system:vtmaster
|
|
/dev/ptmx /dev/ptmx 5 2 system
|
|
/dev/console /dev/console 5 1 system:console
|
|
/dev/tty /dev/tty 5 0 system:/dev/tty
|
|
unknown /dev/tty 4 1-63 console
|
|
|
|
|
|
1.7 Miscellaneous kernel statistics in /proc/stat
|
|
-------------------------------------------------
|
|
|
|
Various pieces of information about kernel activity are available in the
|
|
/proc/stat file. All of the numbers reported in this file are aggregates
|
|
since the system first booted. For a quick look, simply cat the file::
|
|
|
|
> cat /proc/stat
|
|
cpu 237902850 368826709 106375398 1873517540 1135548 0 14507935 0 0 0
|
|
cpu0 60045249 91891769 26331539 468411416 495718 0 5739640 0 0 0
|
|
cpu1 59746288 91759249 26609887 468860630 312281 0 4384817 0 0 0
|
|
cpu2 59489247 92985423 26904446 467808813 171668 0 2268998 0 0 0
|
|
cpu3 58622065 92190267 26529524 468436680 155879 0 2114478 0 0 0
|
|
intr 8688370575 8 3373 0 0 0 0 0 0 1 40791 0 0 353317 0 0 0 0 224789828 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 190974333 41958554 123983334 43 0 224593 0 0 0 <more 0's deleted>
|
|
ctxt 22848221062
|
|
btime 1605316999
|
|
processes 746787147
|
|
procs_running 2
|
|
procs_blocked 0
|
|
softirq 12121874454 100099120 3938138295 127375644 2795979 187870761 0 173808342 3072582055 52608 224184354
|
|
|
|
The very first "cpu" line aggregates the numbers in all of the other "cpuN"
|
|
lines. These numbers identify the amount of time the CPU has spent performing
|
|
different kinds of work. Time units are in USER_HZ (typically hundredths of a
|
|
second). The meanings of the columns are as follows, from left to right:
|
|
|
|
- user: normal processes executing in user mode
|
|
- nice: niced processes executing in user mode
|
|
- system: processes executing in kernel mode
|
|
- idle: twiddling thumbs
|
|
- iowait: In a word, iowait stands for waiting for I/O to complete. But there
|
|
are several problems:
|
|
|
|
1. CPU will not wait for I/O to complete, iowait is the time that a task is
|
|
waiting for I/O to complete. When CPU goes into idle state for
|
|
outstanding task I/O, another task will be scheduled on this CPU.
|
|
2. In a multi-core CPU, the task waiting for I/O to complete is not running
|
|
on any CPU, so the iowait of each CPU is difficult to calculate.
|
|
3. The value of iowait field in /proc/stat will decrease in certain
|
|
conditions.
|
|
|
|
So, the iowait is not reliable by reading from /proc/stat.
|
|
- irq: servicing interrupts
|
|
- softirq: servicing softirqs
|
|
- steal: involuntary wait
|
|
- guest: running a normal guest
|
|
- guest_nice: running a niced guest
|
|
|
|
The "intr" line gives counts of interrupts serviced since boot time, for each
|
|
of the possible system interrupts. The first column is the total of all
|
|
interrupts serviced including unnumbered architecture specific interrupts;
|
|
each subsequent column is the total for that particular numbered interrupt.
|
|
Unnumbered interrupts are not shown, only summed into the total.
|
|
|
|
The "ctxt" line gives the total number of context switches across all CPUs.
|
|
|
|
The "btime" line gives the time at which the system booted, in seconds since
|
|
the Unix epoch.
|
|
|
|
The "processes" line gives the number of processes and threads created, which
|
|
includes (but is not limited to) those created by calls to the fork() and
|
|
clone() system calls.
|
|
|
|
The "procs_running" line gives the total number of threads that are
|
|
running or ready to run (i.e., the total number of runnable threads).
|
|
|
|
The "procs_blocked" line gives the number of processes currently blocked,
|
|
waiting for I/O to complete.
|
|
|
|
The "softirq" line gives counts of softirqs serviced since boot time, for each
|
|
of the possible system softirqs. The first column is the total of all
|
|
softirqs serviced; each subsequent column is the total for that particular
|
|
softirq.
|
|
|
|
|
|
1.8 Ext4 file system parameters
|
|
-------------------------------
|
|
|
|
Information about mounted ext4 file systems can be found in
|
|
/proc/fs/ext4. Each mounted filesystem will have a directory in
|
|
/proc/fs/ext4 based on its device name (i.e., /proc/fs/ext4/hdc or
|
|
/proc/fs/ext4/sda9 or /proc/fs/ext4/dm-0). The files in each per-device
|
|
directory are shown in Table 1-12, below.
|
|
|
|
.. table:: Table 1-12: Files in /proc/fs/ext4/<devname>
|
|
|
|
============== ==========================================================
|
|
File Content
|
|
mb_groups details of multiblock allocator buddy cache of free blocks
|
|
============== ==========================================================
|
|
|
|
1.9 /proc/consoles
|
|
-------------------
|
|
Shows registered system console lines.
|
|
|
|
To see which character device lines are currently used for the system console
|
|
/dev/console, you may simply look into the file /proc/consoles::
|
|
|
|
> cat /proc/consoles
|
|
tty0 -WU (ECp) 4:7
|
|
ttyS0 -W- (Ep) 4:64
|
|
|
|
The columns are:
|
|
|
|
+--------------------+-------------------------------------------------------+
|
|
| device | name of the device |
|
|
+====================+=======================================================+
|
|
| operations | * R = can do read operations |
|
|
| | * W = can do write operations |
|
|
| | * U = can do unblank |
|
|
+--------------------+-------------------------------------------------------+
|
|
| flags | * E = it is enabled |
|
|
| | * C = it is preferred console |
|
|
| | * B = it is primary boot console |
|
|
| | * p = it is used for printk buffer |
|
|
| | * b = it is not a TTY but a Braille device |
|
|
| | * a = it is safe to use when cpu is offline |
|
|
+--------------------+-------------------------------------------------------+
|
|
| major:minor | major and minor number of the device separated by a |
|
|
| | colon |
|
|
+--------------------+-------------------------------------------------------+
|
|
|
|
Summary
|
|
-------
|
|
|
|
The /proc file system serves information about the running system. It not only
|
|
allows access to process data but also allows you to request the kernel status
|
|
by reading files in the hierarchy.
|
|
|
|
The directory structure of /proc reflects the types of information and makes
|
|
it easy, if not obvious, where to look for specific data.
|
|
|
|
Chapter 2: Modifying System Parameters
|
|
======================================
|
|
|
|
In This Chapter
|
|
---------------
|
|
|
|
* Modifying kernel parameters by writing into files found in /proc/sys
|
|
* Exploring the files which modify certain parameters
|
|
* Review of the /proc/sys file tree
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
A very interesting part of /proc is the directory /proc/sys. This is not only
|
|
a source of information, it also allows you to change parameters within the
|
|
kernel. Be very careful when attempting this. You can optimize your system,
|
|
but you can also cause it to crash. Never alter kernel parameters on a
|
|
production system. Set up a development machine and test to make sure that
|
|
everything works the way you want it to. You may have no alternative but to
|
|
reboot the machine once an error has been made.
|
|
|
|
To change a value, simply echo the new value into the file.
|
|
You need to be root to do this. You can create your own boot script
|
|
to perform this every time your system boots.
|
|
|
|
The files in /proc/sys can be used to fine tune and monitor miscellaneous and
|
|
general things in the operation of the Linux kernel. Since some of the files
|
|
can inadvertently disrupt your system, it is advisable to read both
|
|
documentation and source before actually making adjustments. In any case, be
|
|
very careful when writing to any of these files. The entries in /proc may
|
|
change slightly between the 2.1.* and the 2.2 kernel, so if there is any doubt
|
|
review the kernel documentation in the directory linux/Documentation.
|
|
This chapter is heavily based on the documentation included in the pre 2.2
|
|
kernels, and became part of it in version 2.2.1 of the Linux kernel.
|
|
|
|
Please see: Documentation/admin-guide/sysctl/ directory for descriptions of
|
|
these entries.
|
|
|
|
Summary
|
|
-------
|
|
|
|
Certain aspects of kernel behavior can be modified at runtime, without the
|
|
need to recompile the kernel, or even to reboot the system. The files in the
|
|
/proc/sys tree can not only be read, but also modified. You can use the echo
|
|
command to write value into these files, thereby changing the default settings
|
|
of the kernel.
|
|
|
|
|
|
Chapter 3: Per-process Parameters
|
|
=================================
|
|
|
|
3.1 /proc/<pid>/oom_adj & /proc/<pid>/oom_score_adj- Adjust the oom-killer score
|
|
--------------------------------------------------------------------------------
|
|
|
|
These files can be used to adjust the badness heuristic used to select which
|
|
process gets killed in out of memory (oom) conditions.
|
|
|
|
The badness heuristic assigns a value to each candidate task ranging from 0
|
|
(never kill) to 1000 (always kill) to determine which process is targeted. The
|
|
units are roughly a proportion along that range of allowed memory the process
|
|
may allocate from based on an estimation of its current memory and swap use.
|
|
For example, if a task is using all allowed memory, its badness score will be
|
|
1000. If it is using half of its allowed memory, its score will be 500.
|
|
|
|
The amount of "allowed" memory depends on the context in which the oom killer
|
|
was called. If it is due to the memory assigned to the allocating task's cpuset
|
|
being exhausted, the allowed memory represents the set of mems assigned to that
|
|
cpuset. If it is due to a mempolicy's node(s) being exhausted, the allowed
|
|
memory represents the set of mempolicy nodes. If it is due to a memory
|
|
limit (or swap limit) being reached, the allowed memory is that configured
|
|
limit. Finally, if it is due to the entire system being out of memory, the
|
|
allowed memory represents all allocatable resources.
|
|
|
|
The value of /proc/<pid>/oom_score_adj is added to the badness score before it
|
|
is used to determine which task to kill. Acceptable values range from -1000
|
|
(OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This allows userspace to
|
|
polarize the preference for oom killing either by always preferring a certain
|
|
task or completely disabling it. The lowest possible value, -1000, is
|
|
equivalent to disabling oom killing entirely for that task since it will always
|
|
report a badness score of 0.
|
|
|
|
Consequently, it is very simple for userspace to define the amount of memory to
|
|
consider for each task. Setting a /proc/<pid>/oom_score_adj value of +500, for
|
|
example, is roughly equivalent to allowing the remainder of tasks sharing the
|
|
same system, cpuset, mempolicy, or memory controller resources to use at least
|
|
50% more memory. A value of -500, on the other hand, would be roughly
|
|
equivalent to discounting 50% of the task's allowed memory from being considered
|
|
as scoring against the task.
|
|
|
|
For backwards compatibility with previous kernels, /proc/<pid>/oom_adj may also
|
|
be used to tune the badness score. Its acceptable values range from -16
|
|
(OOM_ADJUST_MIN) to +15 (OOM_ADJUST_MAX) and a special value of -17
|
|
(OOM_DISABLE) to disable oom killing entirely for that task. Its value is
|
|
scaled linearly with /proc/<pid>/oom_score_adj.
|
|
|
|
The value of /proc/<pid>/oom_score_adj may be reduced no lower than the last
|
|
value set by a CAP_SYS_RESOURCE process. To reduce the value any lower
|
|
requires CAP_SYS_RESOURCE.
|
|
|
|
|
|
3.2 /proc/<pid>/oom_score - Display current oom-killer score
|
|
-------------------------------------------------------------
|
|
|
|
This file can be used to check the current score used by the oom-killer for
|
|
any given <pid>. Use it together with /proc/<pid>/oom_score_adj to tune which
|
|
process should be killed in an out-of-memory situation.
|
|
|
|
Please note that the exported value includes oom_score_adj so it is
|
|
effectively in range [0,2000].
|
|
|
|
|
|
3.3 /proc/<pid>/io - Display the IO accounting fields
|
|
-------------------------------------------------------
|
|
|
|
This file contains IO statistics for each running process.
|
|
|
|
Example
|
|
~~~~~~~
|
|
|
|
::
|
|
|
|
test:/tmp # dd if=/dev/zero of=/tmp/test.dat &
|
|
[1] 3828
|
|
|
|
test:/tmp # cat /proc/3828/io
|
|
rchar: 323934931
|
|
wchar: 323929600
|
|
syscr: 632687
|
|
syscw: 632675
|
|
read_bytes: 0
|
|
write_bytes: 323932160
|
|
cancelled_write_bytes: 0
|
|
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
rchar
|
|
^^^^^
|
|
|
|
I/O counter: chars read
|
|
The number of bytes which this task has caused to be read from storage. This
|
|
is simply the sum of bytes which this process passed to read() and pread().
|
|
It includes things like tty IO and it is unaffected by whether or not actual
|
|
physical disk IO was required (the read might have been satisfied from
|
|
pagecache).
|
|
|
|
|
|
wchar
|
|
^^^^^
|
|
|
|
I/O counter: chars written
|
|
The number of bytes which this task has caused, or shall cause to be written
|
|
to disk. Similar caveats apply here as with rchar.
|
|
|
|
|
|
syscr
|
|
^^^^^
|
|
|
|
I/O counter: read syscalls
|
|
Attempt to count the number of read I/O operations, i.e. syscalls like read()
|
|
and pread().
|
|
|
|
|
|
syscw
|
|
^^^^^
|
|
|
|
I/O counter: write syscalls
|
|
Attempt to count the number of write I/O operations, i.e. syscalls like
|
|
write() and pwrite().
|
|
|
|
|
|
read_bytes
|
|
^^^^^^^^^^
|
|
|
|
I/O counter: bytes read
|
|
Attempt to count the number of bytes which this process really did cause to
|
|
be fetched from the storage layer. Done at the submit_bio() level, so it is
|
|
accurate for block-backed filesystems. <please add status regarding NFS and
|
|
CIFS at a later time>
|
|
|
|
|
|
write_bytes
|
|
^^^^^^^^^^^
|
|
|
|
I/O counter: bytes written
|
|
Attempt to count the number of bytes which this process caused to be sent to
|
|
the storage layer. This is done at page-dirtying time.
|
|
|
|
|
|
cancelled_write_bytes
|
|
^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
The big inaccuracy here is truncate. If a process writes 1MB to a file and
|
|
then deletes the file, it will in fact perform no writeout. But it will have
|
|
been accounted as having caused 1MB of write.
|
|
In other words: The number of bytes which this process caused to not happen,
|
|
by truncating pagecache. A task can cause "negative" IO too. If this task
|
|
truncates some dirty pagecache, some IO which another task has been accounted
|
|
for (in its write_bytes) will not be happening. We _could_ just subtract that
|
|
from the truncating task's write_bytes, but there is information loss in doing
|
|
that.
|
|
|
|
|
|
.. Note::
|
|
|
|
At its current implementation state, this is a bit racy on 32-bit machines:
|
|
if process A reads process B's /proc/pid/io while process B is updating one
|
|
of those 64-bit counters, process A could see an intermediate result.
|
|
|
|
|
|
More information about this can be found within the taskstats documentation in
|
|
Documentation/accounting.
|
|
|
|
3.4 /proc/<pid>/coredump_filter - Core dump filtering settings
|
|
---------------------------------------------------------------
|
|
When a process is dumped, all anonymous memory is written to a core file as
|
|
long as the size of the core file isn't limited. But sometimes we don't want
|
|
to dump some memory segments, for example, huge shared memory or DAX.
|
|
Conversely, sometimes we want to save file-backed memory segments into a core
|
|
file, not only the individual files.
|
|
|
|
/proc/<pid>/coredump_filter allows you to customize which memory segments
|
|
will be dumped when the <pid> process is dumped. coredump_filter is a bitmask
|
|
of memory types. If a bit of the bitmask is set, memory segments of the
|
|
corresponding memory type are dumped, otherwise they are not dumped.
|
|
|
|
The following 9 memory types are supported:
|
|
|
|
- (bit 0) anonymous private memory
|
|
- (bit 1) anonymous shared memory
|
|
- (bit 2) file-backed private memory
|
|
- (bit 3) file-backed shared memory
|
|
- (bit 4) ELF header pages in file-backed private memory areas (it is
|
|
effective only if the bit 2 is cleared)
|
|
- (bit 5) hugetlb private memory
|
|
- (bit 6) hugetlb shared memory
|
|
- (bit 7) DAX private memory
|
|
- (bit 8) DAX shared memory
|
|
|
|
Note that MMIO pages such as frame buffer are never dumped and vDSO pages
|
|
are always dumped regardless of the bitmask status.
|
|
|
|
Note that bits 0-4 don't affect hugetlb or DAX memory. hugetlb memory is
|
|
only affected by bit 5-6, and DAX is only affected by bits 7-8.
|
|
|
|
The default value of coredump_filter is 0x33; this means all anonymous memory
|
|
segments, ELF header pages and hugetlb private memory are dumped.
|
|
|
|
If you don't want to dump all shared memory segments attached to pid 1234,
|
|
write 0x31 to the process's proc file::
|
|
|
|
$ echo 0x31 > /proc/1234/coredump_filter
|
|
|
|
When a new process is created, the process inherits the bitmask status from its
|
|
parent. It is useful to set up coredump_filter before the program runs.
|
|
For example::
|
|
|
|
$ echo 0x7 > /proc/self/coredump_filter
|
|
$ ./some_program
|
|
|
|
3.5 /proc/<pid>/mountinfo - Information about mounts
|
|
--------------------------------------------------------
|
|
|
|
This file contains lines of the form::
|
|
|
|
36 35 98:0 /mnt1 /mnt2 rw,noatime master:1 - ext3 /dev/root rw,errors=continue
|
|
(1)(2)(3) (4) (5) (6) (n…m) (m+1)(m+2) (m+3) (m+4)
|
|
|
|
(1) mount ID: unique identifier of the mount (may be reused after umount)
|
|
(2) parent ID: ID of parent (or of self for the top of the mount tree)
|
|
(3) major:minor: value of st_dev for files on filesystem
|
|
(4) root: root of the mount within the filesystem
|
|
(5) mount point: mount point relative to the process's root
|
|
(6) mount options: per mount options
|
|
(n…m) optional fields: zero or more fields of the form "tag[:value]"
|
|
(m+1) separator: marks the end of the optional fields
|
|
(m+2) filesystem type: name of filesystem of the form "type[.subtype]"
|
|
(m+3) mount source: filesystem specific information or "none"
|
|
(m+4) super options: per super block options
|
|
|
|
Parsers should ignore all unrecognised optional fields. Currently the
|
|
possible optional fields are:
|
|
|
|
================ ==============================================================
|
|
shared:X mount is shared in peer group X
|
|
master:X mount is slave to peer group X
|
|
propagate_from:X mount is slave and receives propagation from peer group X [#]_
|
|
unbindable mount is unbindable
|
|
================ ==============================================================
|
|
|
|
.. [#] X is the closest dominant peer group under the process's root. If
|
|
X is the immediate master of the mount, or if there's no dominant peer
|
|
group under the same root, then only the "master:X" field is present
|
|
and not the "propagate_from:X" field.
|
|
|
|
For more information on mount propagation see:
|
|
|
|
Documentation/filesystems/sharedsubtree.rst
|
|
|
|
|
|
3.6 /proc/<pid>/comm & /proc/<pid>/task/<tid>/comm
|
|
--------------------------------------------------------
|
|
These files provide a method to access a task's comm value. It also allows for
|
|
a task to set its own or one of its thread siblings comm value. The comm value
|
|
is limited in size compared to the cmdline value, so writing anything longer
|
|
then the kernel's TASK_COMM_LEN (currently 16 chars, including the NUL
|
|
terminator) will result in a truncated comm value.
|
|
|
|
|
|
3.7 /proc/<pid>/task/<tid>/children - Information about task children
|
|
-------------------------------------------------------------------------
|
|
This file provides a fast way to retrieve first level children pids
|
|
of a task pointed by <pid>/<tid> pair. The format is a space separated
|
|
stream of pids.
|
|
|
|
Note the "first level" here -- if a child has its own children they will
|
|
not be listed here; one needs to read /proc/<children-pid>/task/<tid>/children
|
|
to obtain the descendants.
|
|
|
|
Since this interface is intended to be fast and cheap it doesn't
|
|
guarantee to provide precise results and some children might be
|
|
skipped, especially if they've exited right after we printed their
|
|
pids, so one needs to either stop or freeze processes being inspected
|
|
if precise results are needed.
|
|
|
|
|
|
3.8 /proc/<pid>/fdinfo/<fd> - Information about opened file
|
|
---------------------------------------------------------------
|
|
This file provides information associated with an opened file. The regular
|
|
files have at least four fields -- 'pos', 'flags', 'mnt_id' and 'ino'.
|
|
The 'pos' represents the current offset of the opened file in decimal
|
|
form [see lseek(2) for details], 'flags' denotes the octal O_xxx mask the
|
|
file has been created with [see open(2) for details] and 'mnt_id' represents
|
|
mount ID of the file system containing the opened file [see 3.5
|
|
/proc/<pid>/mountinfo for details]. 'ino' represents the inode number of
|
|
the file.
|
|
|
|
A typical output is::
|
|
|
|
pos: 0
|
|
flags: 0100002
|
|
mnt_id: 19
|
|
ino: 63107
|
|
|
|
All locks associated with a file descriptor are shown in its fdinfo too::
|
|
|
|
lock: 1: FLOCK ADVISORY WRITE 359 00:13:11691 0 EOF
|
|
|
|
The files such as eventfd, fsnotify, signalfd, epoll among the regular pos/flags
|
|
pair provide additional information particular to the objects they represent.
|
|
|
|
Eventfd files
|
|
~~~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
pos: 0
|
|
flags: 04002
|
|
mnt_id: 9
|
|
ino: 63107
|
|
eventfd-count: 5a
|
|
|
|
where 'eventfd-count' is hex value of a counter.
|
|
|
|
Signalfd files
|
|
~~~~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
pos: 0
|
|
flags: 04002
|
|
mnt_id: 9
|
|
ino: 63107
|
|
sigmask: 0000000000000200
|
|
|
|
where 'sigmask' is hex value of the signal mask associated
|
|
with a file.
|
|
|
|
Epoll files
|
|
~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
pos: 0
|
|
flags: 02
|
|
mnt_id: 9
|
|
ino: 63107
|
|
tfd: 5 events: 1d data: ffffffffffffffff pos:0 ino:61af sdev:7
|
|
|
|
where 'tfd' is a target file descriptor number in decimal form,
|
|
'events' is events mask being watched and the 'data' is data
|
|
associated with a target [see epoll(7) for more details].
|
|
|
|
The 'pos' is current offset of the target file in decimal form
|
|
[see lseek(2)], 'ino' and 'sdev' are inode and device numbers
|
|
where target file resides, all in hex format.
|
|
|
|
Fsnotify files
|
|
~~~~~~~~~~~~~~
|
|
For inotify files the format is the following::
|
|
|
|
pos: 0
|
|
flags: 02000000
|
|
mnt_id: 9
|
|
ino: 63107
|
|
inotify wd:3 ino:9e7e sdev:800013 mask:800afce ignored_mask:0 fhandle-bytes:8 fhandle-type:1 f_handle:7e9e0000640d1b6d
|
|
|
|
where 'wd' is a watch descriptor in decimal form, i.e. a target file
|
|
descriptor number, 'ino' and 'sdev' are inode and device where the
|
|
target file resides and the 'mask' is the mask of events, all in hex
|
|
form [see inotify(7) for more details].
|
|
|
|
If the kernel was built with exportfs support, the path to the target
|
|
file is encoded as a file handle. The file handle is provided by three
|
|
fields 'fhandle-bytes', 'fhandle-type' and 'f_handle', all in hex
|
|
format.
|
|
|
|
If the kernel is built without exportfs support the file handle won't be
|
|
printed out.
|
|
|
|
If there is no inotify mark attached yet the 'inotify' line will be omitted.
|
|
|
|
For fanotify files the format is::
|
|
|
|
pos: 0
|
|
flags: 02
|
|
mnt_id: 9
|
|
ino: 63107
|
|
fanotify flags:10 event-flags:0
|
|
fanotify mnt_id:12 mflags:40 mask:38 ignored_mask:40000003
|
|
fanotify ino:4f969 sdev:800013 mflags:0 mask:3b ignored_mask:40000000 fhandle-bytes:8 fhandle-type:1 f_handle:69f90400c275b5b4
|
|
|
|
where fanotify 'flags' and 'event-flags' are values used in fanotify_init
|
|
call, 'mnt_id' is the mount point identifier, 'mflags' is the value of
|
|
flags associated with mark which are tracked separately from events
|
|
mask. 'ino' and 'sdev' are target inode and device, 'mask' is the events
|
|
mask and 'ignored_mask' is the mask of events which are to be ignored.
|
|
All are in hex format. Incorporation of 'mflags', 'mask' and 'ignored_mask'
|
|
provide information about flags and mask used in fanotify_mark
|
|
call [see fsnotify manpage for details].
|
|
|
|
While the first three lines are mandatory and always printed, the rest is
|
|
optional and may be omitted if no marks created yet.
|
|
|
|
Timerfd files
|
|
~~~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
pos: 0
|
|
flags: 02
|
|
mnt_id: 9
|
|
ino: 63107
|
|
clockid: 0
|
|
ticks: 0
|
|
settime flags: 01
|
|
it_value: (0, 49406829)
|
|
it_interval: (1, 0)
|
|
|
|
where 'clockid' is the clock type and 'ticks' is the number of the timer expirations
|
|
that have occurred [see timerfd_create(2) for details]. 'settime flags' are
|
|
flags in octal form been used to setup the timer [see timerfd_settime(2) for
|
|
details]. 'it_value' is remaining time until the timer expiration.
|
|
'it_interval' is the interval for the timer. Note the timer might be set up
|
|
with TIMER_ABSTIME option which will be shown in 'settime flags', but 'it_value'
|
|
still exhibits timer's remaining time.
|
|
|
|
DMA Buffer files
|
|
~~~~~~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
pos: 0
|
|
flags: 04002
|
|
mnt_id: 9
|
|
ino: 63107
|
|
size: 32768
|
|
count: 2
|
|
exp_name: system-heap
|
|
|
|
where 'size' is the size of the DMA buffer in bytes. 'count' is the file count of
|
|
the DMA buffer file. 'exp_name' is the name of the DMA buffer exporter.
|
|
|
|
VFIO Device files
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
::
|
|
|
|
pos: 0
|
|
flags: 02000002
|
|
mnt_id: 17
|
|
ino: 5122
|
|
vfio-device-syspath: /sys/devices/pci0000:e0/0000:e0:01.1/0000:e1:00.0/0000:e2:05.0/0000:e8:00.0
|
|
|
|
where 'vfio-device-syspath' is the sysfs path corresponding to the VFIO device
|
|
file.
|
|
|
|
3.9 /proc/<pid>/map_files - Information about memory mapped files
|
|
---------------------------------------------------------------------
|
|
This directory contains symbolic links which represent memory mapped files
|
|
the process is maintaining. Example output::
|
|
|
|
| lr-------- 1 root root 64 Jan 27 11:24 333c600000-333c620000 -> /usr/lib64/ld-2.18.so
|
|
| lr-------- 1 root root 64 Jan 27 11:24 333c81f000-333c820000 -> /usr/lib64/ld-2.18.so
|
|
| lr-------- 1 root root 64 Jan 27 11:24 333c820000-333c821000 -> /usr/lib64/ld-2.18.so
|
|
| ...
|
|
| lr-------- 1 root root 64 Jan 27 11:24 35d0421000-35d0422000 -> /usr/lib64/libselinux.so.1
|
|
| lr-------- 1 root root 64 Jan 27 11:24 400000-41a000 -> /usr/bin/ls
|
|
|
|
The name of a link represents the virtual memory bounds of a mapping, i.e.
|
|
vm_area_struct::vm_start - vm_area_struct::vm_end.
|
|
|
|
The main purpose of the map_files is to retrieve a set of memory mapped
|
|
files in a fast way instead of parsing /proc/<pid>/maps or
|
|
/proc/<pid>/smaps, both of which contain many more records. At the same
|
|
time one can open(2) mappings from the listings of two processes and
|
|
comparing their inode numbers to figure out which anonymous memory areas
|
|
are actually shared.
|
|
|
|
3.10 /proc/<pid>/timerslack_ns - Task timerslack value
|
|
---------------------------------------------------------
|
|
This file provides the value of the task's timerslack value in nanoseconds.
|
|
This value specifies an amount of time that normal timers may be deferred
|
|
in order to coalesce timers and avoid unnecessary wakeups.
|
|
|
|
This allows a task's interactivity vs power consumption tradeoff to be
|
|
adjusted.
|
|
|
|
Writing 0 to the file will set the task's timerslack to the default value.
|
|
|
|
Valid values are from 0 - ULLONG_MAX
|
|
|
|
An application setting the value must have PTRACE_MODE_ATTACH_FSCREDS level
|
|
permissions on the task specified to change its timerslack_ns value.
|
|
|
|
3.11 /proc/<pid>/patch_state - Livepatch patch operation state
|
|
-----------------------------------------------------------------
|
|
When CONFIG_LIVEPATCH is enabled, this file displays the value of the
|
|
patch state for the task.
|
|
|
|
A value of '-1' indicates that no patch is in transition.
|
|
|
|
A value of '0' indicates that a patch is in transition and the task is
|
|
unpatched. If the patch is being enabled, then the task hasn't been
|
|
patched yet. If the patch is being disabled, then the task has already
|
|
been unpatched.
|
|
|
|
A value of '1' indicates that a patch is in transition and the task is
|
|
patched. If the patch is being enabled, then the task has already been
|
|
patched. If the patch is being disabled, then the task hasn't been
|
|
unpatched yet.
|
|
|
|
3.12 /proc/<pid>/arch_status - task architecture specific status
|
|
-------------------------------------------------------------------
|
|
When CONFIG_PROC_PID_ARCH_STATUS is enabled, this file displays the
|
|
architecture specific status of the task.
|
|
|
|
Example
|
|
~~~~~~~
|
|
|
|
::
|
|
|
|
$ cat /proc/6753/arch_status
|
|
AVX512_elapsed_ms: 8
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
x86 specific entries
|
|
~~~~~~~~~~~~~~~~~~~~~
|
|
|
|
AVX512_elapsed_ms
|
|
^^^^^^^^^^^^^^^^^^
|
|
|
|
If AVX512 is supported on the machine, this entry shows the milliseconds
|
|
elapsed since the last time AVX512 usage was recorded. The recording
|
|
happens on a best effort basis when a task is scheduled out. This means
|
|
that the value depends on two factors:
|
|
|
|
1) The time which the task spent on the CPU without being scheduled
|
|
out. With CPU isolation and a single runnable task this can take
|
|
several seconds.
|
|
|
|
2) The time since the task was scheduled out last. Depending on the
|
|
reason for being scheduled out (time slice exhausted, syscall ...)
|
|
this can be arbitrary long time.
|
|
|
|
As a consequence the value cannot be considered precise and authoritative
|
|
information. The application which uses this information has to be aware
|
|
of the overall scenario on the system in order to determine whether a
|
|
task is a real AVX512 user or not. Precise information can be obtained
|
|
with performance counters.
|
|
|
|
A special value of '-1' indicates that no AVX512 usage was recorded, thus
|
|
the task is unlikely an AVX512 user, but depends on the workload and the
|
|
scheduling scenario, it also could be a false negative mentioned above.
|
|
|
|
3.13 /proc/<pid>/fd - List of symlinks to open files
|
|
-------------------------------------------------------
|
|
This directory contains symbolic links which represent open files
|
|
the process is maintaining. Example output::
|
|
|
|
lr-x------ 1 root root 64 Sep 20 17:53 0 -> /dev/null
|
|
l-wx------ 1 root root 64 Sep 20 17:53 1 -> /dev/null
|
|
lrwx------ 1 root root 64 Sep 20 17:53 10 -> 'socket:[12539]'
|
|
lrwx------ 1 root root 64 Sep 20 17:53 11 -> 'socket:[12540]'
|
|
lrwx------ 1 root root 64 Sep 20 17:53 12 -> 'socket:[12542]'
|
|
|
|
The number of open files for the process is stored in 'size' member
|
|
of stat() output for /proc/<pid>/fd for fast access.
|
|
-------------------------------------------------------
|
|
|
|
3.14 /proc/<pid>/ksm_stat - Information about the process's ksm status
|
|
----------------------------------------------------------------------
|
|
When CONFIG_KSM is enabled, each process has this file which displays
|
|
the information of ksm merging status.
|
|
|
|
Example
|
|
~~~~~~~
|
|
|
|
::
|
|
|
|
/ # cat /proc/self/ksm_stat
|
|
ksm_rmap_items 0
|
|
ksm_zero_pages 0
|
|
ksm_merging_pages 0
|
|
ksm_process_profit 0
|
|
ksm_merge_any: no
|
|
ksm_mergeable: no
|
|
|
|
Description
|
|
~~~~~~~~~~~
|
|
|
|
ksm_rmap_items
|
|
^^^^^^^^^^^^^^
|
|
|
|
The number of ksm_rmap_item structures in use. The structure
|
|
ksm_rmap_item stores the reverse mapping information for virtual
|
|
addresses. KSM will generate a ksm_rmap_item for each ksm-scanned page of
|
|
the process.
|
|
|
|
ksm_zero_pages
|
|
^^^^^^^^^^^^^^
|
|
|
|
When /sys/kernel/mm/ksm/use_zero_pages is enabled, it represent how many
|
|
empty pages are merged with kernel zero pages by KSM.
|
|
|
|
ksm_merging_pages
|
|
^^^^^^^^^^^^^^^^^
|
|
|
|
It represents how many pages of this process are involved in KSM merging
|
|
(not including ksm_zero_pages). It is the same with what
|
|
/proc/<pid>/ksm_merging_pages shows.
|
|
|
|
ksm_process_profit
|
|
^^^^^^^^^^^^^^^^^^
|
|
|
|
The profit that KSM brings (Saved bytes). KSM can save memory by merging
|
|
identical pages, but also can consume additional memory, because it needs
|
|
to generate a number of rmap_items to save each scanned page's brief rmap
|
|
information. Some of these pages may be merged, but some may not be abled
|
|
to be merged after being checked several times, which are unprofitable
|
|
memory consumed.
|
|
|
|
ksm_merge_any
|
|
^^^^^^^^^^^^^
|
|
|
|
It specifies whether the process's 'mm is added by prctl() into the
|
|
candidate list of KSM or not, and if KSM scanning is fully enabled at
|
|
process level.
|
|
|
|
ksm_mergeable
|
|
^^^^^^^^^^^^^
|
|
|
|
It specifies whether any VMAs of the process''s mms are currently
|
|
applicable to KSM.
|
|
|
|
More information about KSM can be found in
|
|
Documentation/admin-guide/mm/ksm.rst.
|
|
|
|
|
|
Chapter 4: Configuring procfs
|
|
=============================
|
|
|
|
4.1 Mount options
|
|
---------------------
|
|
|
|
The following mount options are supported:
|
|
|
|
========= ========================================================
|
|
hidepid= Set /proc/<pid>/ access mode.
|
|
gid= Set the group authorized to learn processes information.
|
|
subset= Show only the specified subset of procfs.
|
|
pidns= Specify a the namespace used by this procfs.
|
|
========= ========================================================
|
|
|
|
hidepid=off or hidepid=0 means classic mode - everybody may access all
|
|
/proc/<pid>/ directories (default).
|
|
|
|
hidepid=noaccess or hidepid=1 means users may not access any /proc/<pid>/
|
|
directories but their own. Sensitive files like cmdline, sched*, status are now
|
|
protected against other users. This makes it impossible to learn whether any
|
|
user runs specific program (given the program doesn't reveal itself by its
|
|
behaviour). As an additional bonus, as /proc/<pid>/cmdline is unaccessible for
|
|
other users, poorly written programs passing sensitive information via program
|
|
arguments are now protected against local eavesdroppers.
|
|
|
|
hidepid=invisible or hidepid=2 means hidepid=1 plus all /proc/<pid>/ will be
|
|
fully invisible to other users. It doesn't mean that it hides a fact whether a
|
|
process with a specific pid value exists (it can be learned by other means, e.g.
|
|
by "kill -0 $PID"), but it hides process's uid and gid, which may be learned by
|
|
stat()'ing /proc/<pid>/ otherwise. It greatly complicates an intruder's task of
|
|
gathering information about running processes, whether some daemon runs with
|
|
elevated privileges, whether other user runs some sensitive program, whether
|
|
other users run any program at all, etc.
|
|
|
|
hidepid=ptraceable or hidepid=4 means that procfs should only contain
|
|
/proc/<pid>/ directories that the caller can ptrace.
|
|
|
|
gid= defines a group authorized to learn processes information otherwise
|
|
prohibited by hidepid=. If you use some daemon like identd which needs to learn
|
|
information about processes information, just add identd to this group.
|
|
|
|
subset=pid hides all top level files and directories in the procfs that
|
|
are not related to tasks. This option cannot be changed on an existing
|
|
procfs instance because overmounts that existed before the change could
|
|
otherwise remain reachable after the top level procfs entries are hidden.
|
|
|
|
pidns= specifies a pid namespace (either as a string path to something like
|
|
`/proc/$pid/ns/pid`, or a file descriptor when using `FSCONFIG_SET_FD`) that
|
|
will be used by the procfs instance when translating pids. By default, procfs
|
|
will use the calling process's active pid namespace. Note that the pid
|
|
namespace of an existing procfs instance cannot be modified (attempting to do
|
|
so will give an `-EBUSY` error).
|
|
|
|
4.2 Mount restrictions
|
|
--------------------------
|
|
|
|
If user namespaces are in use, the kernel additionally checks the instances of
|
|
procfs available to the mounter and will not allow procfs to be mounted if:
|
|
|
|
1. This mount is not fully visible unless the new procfs is going to be
|
|
mounted with subset=pid option.
|
|
|
|
a. Its root directory is not the root directory of the filesystem.
|
|
b. If any file or non-empty procfs directory is hidden by another mount.
|
|
|
|
2. A new mount overrides the readonly option or any option from atime family.
|
|
|
|
Chapter 5: Filesystem behavior
|
|
==============================
|
|
|
|
Originally, before the advent of pid namespace, procfs was a global file
|
|
system. It means that there was only one procfs instance in the system.
|
|
|
|
When pid namespace was added, a separate procfs instance was mounted in
|
|
each pid namespace. So, procfs mount options are global among all
|
|
mountpoints within the same namespace::
|
|
|
|
# grep ^proc /proc/mounts
|
|
proc /proc proc rw,relatime,hidepid=2 0 0
|
|
|
|
# strace -e mount mount -o hidepid=1 -t proc proc /tmp/proc
|
|
mount("proc", "/tmp/proc", "proc", 0, "hidepid=1") = 0
|
|
+++ exited with 0 +++
|
|
|
|
# grep ^proc /proc/mounts
|
|
proc /proc proc rw,relatime,hidepid=2 0 0
|
|
proc /tmp/proc proc rw,relatime,hidepid=2 0 0
|
|
|
|
and only after remounting procfs mount options will change at all
|
|
mountpoints::
|
|
|
|
# mount -o remount,hidepid=1 -t proc proc /tmp/proc
|
|
|
|
# grep ^proc /proc/mounts
|
|
proc /proc proc rw,relatime,hidepid=1 0 0
|
|
proc /tmp/proc proc rw,relatime,hidepid=1 0 0
|
|
|
|
This behavior is different from the behavior of other filesystems.
|
|
|
|
The new procfs behavior is more like other filesystems. Each procfs mount
|
|
creates a new procfs instance. Mount options affect own procfs instance.
|
|
It means that it became possible to have several procfs instances
|
|
displaying tasks with different filtering options in one pid namespace::
|
|
|
|
# mount -o hidepid=invisible -t proc proc /proc
|
|
# mount -o hidepid=noaccess -t proc proc /tmp/proc
|
|
# grep ^proc /proc/mounts
|
|
proc /proc proc rw,relatime,hidepid=invisible 0 0
|
|
proc /tmp/proc proc rw,relatime,hidepid=noaccess 0 0
|