Simplify the scheduler by making CONFIG_SMP=y code in the stop-CPU
scheduling class unconditional.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-36-mingo@kernel.org
Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional in the RT policies scheduler.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-29-mingo@kernel.org
Simplify the scheduler by making the CONFIG_SMP=y version of
idle_thread_set_boot_cpu() unconditional.
Note that idle_thread_set_boot_cpu() is already conditional
on CONFIG_GENERIC_SMP_IDLE_THREAD, which most architectures
select unconditionally on both UP and SMP kernels.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-28-mingo@kernel.org
Simplify the scheduler by making CONFIG_SMP=y data structure
of rq->hrtick_csd unconditional.
Adjust hrtick_start() accordingly, which was split due to the
::hrtick_csd asymmetry and use the SMP version there too.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-23-mingo@kernel.org
Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional.
Introduce transitory wrappers for functionality not yet converted to SMP.
Note that this patch is pretty large, because there's no clear separation
between various aspects of the SMP scheduler, it's basically a huge block
of #ifdef CONFIG_SMP. A fair amount of it has to be switched on for it to
boot and work on UP systems.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-21-mingo@kernel.org
Simplify the scheduler by making CONFIG_SMP=y primitives and data
structures unconditional.
Unconditionally build kernel/sched/topology.c and the main sched-domains
locking primitives.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://lore.kernel.org/r/20250528080924.2273858-20-mingo@kernel.org
Due to the weird Makefile setup of sched the various files do not
compile as stand alone units. The new generation of editors are trying
to do just this -- mostly to offer fancy things like completions but
also better syntax highlighting and code navigation.
Specifically, I've been playing around with neovim and clangd.
Setting up clangd on the kernel source is a giant pain in the arse
(this really should be improved), but once you do manage, you run into
dumb stuff like the above.
Fix up the scheduler files to at least pretend to work.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20250523164348.GN39944@noisy.programming.kicks-ass.net
Move this API to the canonical timer_*() namespace.
[ tglx: Redone against pre rc1 ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/aB2X0jCKQO56WdMt@gmail.com
Two fixes in the built-in idle selection helpers.
- Fix prev_cpu handling to guarantee that idle selection never returns a CPU
that's not allowed.
- Skip cross-node search when !NUMA which could lead to infinite looping due
to a bug in NUMA iterator.
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Merge tag 'sched_ext-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext fixes from Tejun Heo:
"Two fixes in the built-in idle selection helpers:
- Fix prev_cpu handling to guarantee that idle selection never
returns a CPU that's not allowed
- Skip cross-node search when !NUMA which could lead to infinite
looping due to a bug in NUMA iterator"
* tag 'sched_ext-for-6.16-rc1-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: idle: Skip cross-node search with !CONFIG_NUMA
sched_ext: idle: Properly handle invalid prev_cpu during idle selection
In the idle CPU selection logic, attempting cross-node searches adds
unnecessary complexity when CONFIG_NUMA is disabled.
Since there's no meaningful concept of nodes in this case, simplify the
logic by restricting the idle CPU search to the current node only.
Fixes: 48849271e6 ("sched_ext: idle: Per-node idle cpumasks")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Sergey Senozhatsky adds infrastructure for passing algorithm-specific
parameters into zram. A single parameter `winbits' is implemented at
this time.
- The 5 patch series "memcg: nmi-safe kmem charging" from Shakeel Butt
makes memcg charging nmi-safe, which is required by BFP, which can
operate in NMI context.
- The 5 patch series "Some random fixes and cleanup to shmem" from
Kemeng Shi implements small fixes and cleanups in the shmem code.
- The 2 patch series "Skip mm selftests instead when kernel features are
not present" from Zi Yan fixes some issues in the MM selftest code.
- The 2 patch series "mm/damon: build-enable essential DAMON components
by default" from SeongJae Park reworks DAMON Kconfig to make it easier
to enable CONFIG_DAMON.
- The 2 patch series "sched/numa: add statistics of numa balance task
migration" from Libo Chen adds more info into sysfs and procfs files to
improve visibility into the NUMA balancer's task migration activity.
- The 4 patch series "selftests/mm: cow and gup_longterm cleanups" from
Mark Brown provides various updates to some of the MM selftests to make
them play better with the overall containing framework.
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Merge tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull more MM updates from Andrew Morton:
- "zram: support algorithm-specific parameters" from Sergey Senozhatsky
adds infrastructure for passing algorithm-specific parameters into
zram. A single parameter `winbits' is implemented at this time.
- "memcg: nmi-safe kmem charging" from Shakeel Butt makes memcg
charging nmi-safe, which is required by BFP, which can operate in NMI
context.
- "Some random fixes and cleanup to shmem" from Kemeng Shi implements
small fixes and cleanups in the shmem code.
- "Skip mm selftests instead when kernel features are not present" from
Zi Yan fixes some issues in the MM selftest code.
- "mm/damon: build-enable essential DAMON components by default" from
SeongJae Park reworks DAMON Kconfig to make it easier to enable
CONFIG_DAMON.
- "sched/numa: add statistics of numa balance task migration" from Libo
Chen adds more info into sysfs and procfs files to improve visibility
into the NUMA balancer's task migration activity.
- "selftests/mm: cow and gup_longterm cleanups" from Mark Brown
provides various updates to some of the MM selftests to make them
play better with the overall containing framework.
* tag 'mm-stable-2025-06-01-14-06' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (43 commits)
mm/khugepaged: clean up refcount check using folio_expected_ref_count()
selftests/mm: fix test result reporting in gup_longterm
selftests/mm: report unique test names for each cow test
selftests/mm: add helper for logging test start and results
selftests/mm: use standard ksft_finished() in cow and gup_longterm
selftests/damon/_damon_sysfs: skip testcases if CONFIG_DAMON_SYSFS is disabled
sched/numa: add statistics of numa balance task
sched/numa: fix task swap by skipping kernel threads
tools/testing: check correct variable in open_procmap()
tools/testing/vma: add missing function stub
mm/gup: update comment explaining why gup_fast() disables IRQs
selftests/mm: two fixes for the pfnmap test
mm/khugepaged: fix race with folio split/free using temporary reference
mm: add CONFIG_PAGE_BLOCK_ORDER to select page block order
mmu_notifiers: remove leftover stub macros
selftests/mm: deduplicate test names in madv_populate
kcov: rust: add flags for KCOV with Rust
mm: rust: make CONFIG_MMU ifdefs more narrow
mmu_gather: move tlb flush for VM_PFNMAP/VM_MIXEDMAP vmas into free_pgtables()
mm/damon/Kconfig: enable CONFIG_DAMON by default
...
On systems with NUMA balancing enabled, it has been found that tracking
task activities resulting from NUMA balancing is beneficial. NUMA
balancing employs two mechanisms for task migration: one is to migrate
a task to an idle CPU within its preferred node, and the other is to
swap tasks located on different nodes when they are on each other's
preferred nodes.
The kernel already provides NUMA page migration statistics in
/sys/fs/cgroup/mytest/memory.stat and /proc/{PID}/sched. However, it
lacks statistics regarding task migration and swapping. Therefore,
relevant counts for task migration and swapping should be added.
The following two new fields:
numa_task_migrated
numa_task_swapped
will be shown in /sys/fs/cgroup/{GROUP}/memory.stat, /proc/{PID}/sched
and /proc/vmstat.
Introducing both per-task and per-memory cgroup (memcg) NUMA balancing
statistics facilitates a rapid evaluation of the performance and
resource utilization of the target workload. For instance, users can
first identify the container with high NUMA balancing activity and then
further pinpoint a specific task within that group, and subsequently
adjust the memory policy for that task. In short, although it is
possible to iterate through /proc/$pid/sched to locate the problematic
task, the introduction of aggregated NUMA balancing activity for tasks
within each memcg can assist users in identifying the task more
efficiently through a divide-and-conquer approach.
As Libo Chen pointed out, the memcg event relies on the text names in
vmstat_text, and /proc/vmstat generates corresponding items based on
vmstat_text. Thus, the relevant task migration and swapping events
introduced in vmstat_text also need to be populated by
count_vm_numa_event(), otherwise these values are zero in /proc/vmstat.
In theory, task migration and swap events are part of the scheduler's
activities. The reason for exposing them through the
memory.stat/vmstat interface is that we already have NUMA balancing
statistics in memory.stat/vmstat, and these events are closely related
to each other. Following Shakeel's suggestion, we describe the
end-to-end flow/story of all these events occurring on a timeline for
future reference:
The goal of NUMA balancing is to co-locate a task and its memory pages
on the same NUMA node. There are two strategies: migrate the pages to
the task's node, or migrate the task to the node where its pages
reside.
Suppose a task p1 is running on Node 0, but its pages are located on
Node 1. NUMA page fault statistics for p1 reveal its "page footprint"
across nodes. If NUMA balancing detects that most of p1's pages are on
Node 1:
1.Page Migration Attempt:
The Numa balance first tries to migrate p1's pages to Node 0.
The numa_page_migrate counter increments.
2.Task Migration Strategies:
After the page migration finishes, Numa balance checks every
1 second to see if p1 can be migrated to Node 1.
Case 2.1: Idle CPU Available
If Node 1 has an idle CPU, p1 is directly scheduled there. This
event is logged as numa_task_migrated.
Case 2.2: No Idle CPU (Task Swap)
If all CPUs on Node1 are busy, direct migration could cause CPU
contention or load imbalance. Instead: The Numa balance selects a
candidate task p2 on Node 1 that prefers Node 0 (e.g., due to its own
page footprint). p1 and p2 are swapped. This cross-node swap is
recorded as numa_task_swapped.
Link: https://lkml.kernel.org/r/d00edb12ba0f0de3c5222f61487e65f2ac58f5b1.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/7ef90a88602ed536be46eba7152ed0d33bad5790.1748002400.git.yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: Ayush Jain <Ayush.jain3@amd.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Libo Chen <libo.chen@oracle.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "sched/numa: add statistics of numa balance task migration",
v6.
Introduce task migration and swap statistics in the following places:
/sys/fs/cgroup/{GROUP}/memory.stat
/proc/{PID}/sched
/proc/vmstat
These statistics facilitate a rapid evaluation of the performance and
resource utilization of the target workload.
This patch (of 2):
Task swapping is triggered when there are no idle CPUs in task A's
preferred node. In this case, the NUMA load balancer chooses a task B
on A's preferred node and swaps B with A. This helps improve NUMA
locality without introducing load imbalance between nodes. In the
current implementation, B's NUMA node preference is not mandatory.
That is to say, a kernel thread might be incorrectly chosen as B.
However, kernel thread and user space thread that does not have mm are
not supposed to be covered by NUMA balancing because NUMA balancing
only considers user pages via VMAs.
According to Peter's suggestion for fixing this issue, we use
PF_KTHREAD to skip the kernel thread. curr->mm is also checked because
it is possible that user_mode_thread() might create a user thread
without an mm. As per Prateek's analysis, after adding the PF_KTHREAD
check, there is no need to further check the PF_IDLE flag:
: - play_idle_precise() already ensures PF_KTHREAD is set before adding
: PF_IDLE
:
: - cpu_startup_entry() is only called from the startup thread which
: should be marked with PF_KTHREAD (based on my understanding looking at
: commit cff9b2332a ("kernel/sched: Modify initial boot task idle
: setup"))
In summary, the check in task_numa_compare() now aligns with
task_tick_numa().
Link: https://lkml.kernel.org/r/cover.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/43d68b356b25d124f0d222ebedf3859e86eefb9f.1748493462.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/cover.1748002400.git.yu.c.chen@intel.com
Link: https://lkml.kernel.org/r/eaacc9c9bd37bac92d43a671867d85b2fdad3b06.1748002400.git.yu.c.chen@intel.com
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Libo Chen <libo.chen@oracle.com>
Suggested-by: Michal Koutný <mkoutny@suse.com>
Tested-by: Ayush Jain <Ayush.jain3@amd.com>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Aubrey Li <aubrey.li@intel.com>
Cc: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
simplifies the act of creating a pte which addresses the first page in a
folio and reduces the amount of plumbing which architecture must
implement to provide this.
- The 8 patch series "Misc folio patches for 6.16" from Matthew Wilcox
is a shower of largely unrelated folio infrastructure changes which
clean things up and better prepare us for future work.
- The 3 patch series "memory,x86,acpi: hotplug memory alignment
advisement" from Gregory Price adds early-init code to prevent x86 from
leaving physical memory unused when physical address regions are not
aligned to memory block size.
- The 2 patch series "mm/compaction: allow more aggressive proactive
compaction" from Michal Clapinski provides some tuning of the (sadly,
hard-coded (more sadly, not auto-tuned)) thresholds for our invokation
of proactive compaction. In a simple test case, the reduction of a guest
VM's memory consumption was dramatic.
- The 8 patch series "Minor cleanups and improvements to swap freeing
code" from Kemeng Shi provides some code cleaups and a small efficiency
improvement to this part of our swap handling code.
- The 6 patch series "ptrace: introduce PTRACE_SET_SYSCALL_INFO API"
from Dmitry Levin adds the ability for a ptracer to modify syscalls
arguments. At this time we can alter only "system call information that
are used by strace system call tampering, namely, syscall number,
syscall arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- The 3 patch series "fs/proc: extend the PAGEMAP_SCAN ioctl to report
guard regions" from Andrei Vagin extends the info returned by the
PAGEMAP_SCAN ioctl against /proc/pid/pagemap. This permits CRIU to more
efficiently get at the info about guard regions.
- The 2 patch series "Fix parameter passed to page_mapcount_is_type()"
from Gavin Shan implements that fix. No runtime effect is expected
because validate_page_before_insert() happens to fix up this error.
- The 3 patch series "kernel/events/uprobes: uprobe_write_opcode()
rewrite" from David Hildenbrand basically brings uprobe text poking into
the current decade. Remove a bunch of hand-rolled implementation in
favor of using more current facilities.
- The 3 patch series "mm/ptdump: Drop assumption that pxd_val() is u64"
from Anshuman Khandual provides enhancements and generalizations to the
pte dumping code. This might be needed when 128-bit Page Table
Descriptors are enabled for ARM.
- The 12 patch series "Always call constructor for kernel page tables"
from Kevin Brodsky "ensures that the ctor/dtor is always called for
kernel pgtables, as it already is for user pgtables". This permits the
addition of more functionality such as "insert hooks to protect page
tables". This change does result in various architectures performing
unnecesary work, but this is fixed up where it is anticipated to occur.
- The 9 patch series "Rust support for mm_struct, vm_area_struct, and
mmap" from Alice Ryhl adds plumbing to permit Rust access to core MM
structures.
- The 3 patch series "fix incorrectly disallowed anonymous VMA merges"
from Lorenzo Stoakes takes advantage of some VMA merging opportunities
which we've been missing for 15 years.
- The 4 patch series "mm/madvise: batch tlb flushes for MADV_DONTNEED
and MADV_FREE" from SeongJae Park optimizes process_madvise()'s TLB
flushing. Instead of flushing each address range in the provided iovec,
we batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- The 6 patch series "Track node vacancy to reduce worst case allocation
counts" from Sidhartha Kumar makes the maple tree smarter about its node
preallocation. stress-ng mmap performance increased by single-digit
percentages and the amount of unnecessarily preallocated memory was
dramaticelly reduced.
- The 3 patch series "mm/gup: Minor fix, cleanup and improvements" from
Baoquan He removes a few unnecessary things which Baoquan noted when
reading the code.
- The 3 patch series ""Enhance sysfs handling for memory hotplug in
weighted interleave" from Rakie Kim "enhances the weighted interleave
policy in the memory management subsystem by improving sysfs handling,
fixing memory leaks, and introducing dynamic sysfs updates for memory
hotplug support". Fixes things on error paths which we are unlikely to
hit.
- The 7 patch series "mm/damon: auto-tune DAMOS for NUMA setups
including tiered memory" from SeongJae Park introduces new DAMOS quota
goal metrics which eliminate the manual tuning which is required when
utilizing DAMON for memory tiering.
- The 5 patch series "mm/vmalloc.c: code cleanup and improvements" from
Baoquan He provides cleanups and small efficiency improvements which
Baoquan found via code inspection.
- The 2 patch series "vmscan: enforce mems_effective during demotion"
from Gregory Price "changes reclaim to respect cpuset.mems_effective
during demotion when possible". because "presently, reclaim explicitly
ignores cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated." "This is useful for isolating workloads on a
multi-tenant system from certain classes of memory more consistently."
- The 2 patch series ""Clean up split_huge_pmd_locked() and remove
unnecessary folio pointers" from Gavin Guo provides minor cleanups and
efficiency gains in in the huge page splitting and migrating code.
- The 3 patch series "Use kmem_cache for memcg alloc" from Huan Yang
creates a slab cache for `struct mem_cgroup', yielding improved memory
utilization.
- The 4 patch series "add max arg to swappiness in memory.reclaim and
lru_gen" from Zhongkun He adds a new "max" argument to the "swappiness="
argument for memory.reclaim MGLRU's lru_gen. This directs proactive
reclaim to reclaim from only anon folios rather than file-backed folios.
- The 17 patch series "kexec: introduce Kexec HandOver (KHO)" from Mike
Rapoport is the first step on the path to permitting the kernel to
maintain existing VMs while replacing the host kernel via file-based
kexec. At this time only memblock's reserve_mem is preserved.
- The 7 patch series "mm: Introduce for_each_valid_pfn()" from David
Woodhouse provides and uses a smarter way of looping over a pfn range.
By skipping ranges of invalid pfns.
- The 2 patch series "sched/numa: Skip VMA scanning on memory pinned to
one NUMA node via cpuset.mems" from Libo Chen removes a lot of pointless
VMA scanning when a task is pinned a single NUMA mode. Dramatic
performance benefits were seen in some real world cases.
- The 2 patch series "JFS: Implement migrate_folio for
jfs_metapage_aops" from Shivank Garg addresses a warning which occurs
during memory compaction when using JFS.
- The 4 patch series "move all VMA allocation, freeing and duplication
logic to mm" from Lorenzo Stoakes moves some VMA code from kernel/fork.c
into the more appropriate mm/vma.c.
- The 6 patch series "mm, swap: clean up swap cache mapping helper" from
Kairui Song provides code consolidation and cleanups related to the
folio_index() function.
- The 2 patch series "mm/gup: Cleanup memfd_pin_folios()" from Vishal
Moola does that.
- The 8 patch series "memcg: Fix test_memcg_min/low test failures" from
Waiman Long addresses some bogus failures which are being reported by
the test_memcontrol selftest.
- The 3 patch series "eliminate mmap() retry merge, add .mmap_prepare
hook" from Lorenzo Stoakes commences the deprecation of
file_operations.mmap() in favor of the new
file_operations.mmap_prepare(). The latter is more restrictive and
prevents drivers from messing with things in ways which, amongst other
problems, may defeat VMA merging.
- The 4 patch series "memcg: decouple memcg and objcg stocks"" from
Shakeel Butt decouples the per-cpu memcg charge cache from the objcg's
one. This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- The 6 patch series "mm/damon: minor fixups and improvements for code,
tests, and documents" from SeongJae Park is "yet another batch of
miscellaneous DAMON changes. Fix and improve minor problems in code,
tests and documents."
- The 7 patch series "memcg: make memcg stats irq safe" from Shakeel
Butt converts memcg stats to be irq safe. Another step along the way to
making memcg charging and stats updates NMI-safe, a BPF requirement.
- The 4 patch series "Let unmap_hugepage_range() and several related
functions take folio instead of page" from Fan Ni provides folio
conversions in the hugetlb code.
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Merge tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
creating a pte which addresses the first page in a folio and reduces
the amount of plumbing which architecture must implement to provide
this.
- "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
largely unrelated folio infrastructure changes which clean things up
and better prepare us for future work.
- "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
Price adds early-init code to prevent x86 from leaving physical
memory unused when physical address regions are not aligned to memory
block size.
- "mm/compaction: allow more aggressive proactive compaction" from
Michal Clapinski provides some tuning of the (sadly, hard-coded (more
sadly, not auto-tuned)) thresholds for our invokation of proactive
compaction. In a simple test case, the reduction of a guest VM's
memory consumption was dramatic.
- "Minor cleanups and improvements to swap freeing code" from Kemeng
Shi provides some code cleaups and a small efficiency improvement to
this part of our swap handling code.
- "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
adds the ability for a ptracer to modify syscalls arguments. At this
time we can alter only "system call information that are used by
strace system call tampering, namely, syscall number, syscall
arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
against /proc/pid/pagemap. This permits CRIU to more efficiently get
at the info about guard regions.
- "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
implements that fix. No runtime effect is expected because
validate_page_before_insert() happens to fix up this error.
- "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
Hildenbrand basically brings uprobe text poking into the current
decade. Remove a bunch of hand-rolled implementation in favor of
using more current facilities.
- "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
Khandual provides enhancements and generalizations to the pte dumping
code. This might be needed when 128-bit Page Table Descriptors are
enabled for ARM.
- "Always call constructor for kernel page tables" from Kevin Brodsky
ensures that the ctor/dtor is always called for kernel pgtables, as
it already is for user pgtables.
This permits the addition of more functionality such as "insert hooks
to protect page tables". This change does result in various
architectures performing unnecesary work, but this is fixed up where
it is anticipated to occur.
- "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
Ryhl adds plumbing to permit Rust access to core MM structures.
- "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
Stoakes takes advantage of some VMA merging opportunities which we've
been missing for 15 years.
- "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
SeongJae Park optimizes process_madvise()'s TLB flushing.
Instead of flushing each address range in the provided iovec, we
batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- "Track node vacancy to reduce worst case allocation counts" from
Sidhartha Kumar makes the maple tree smarter about its node
preallocation.
stress-ng mmap performance increased by single-digit percentages and
the amount of unnecessarily preallocated memory was dramaticelly
reduced.
- "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
a few unnecessary things which Baoquan noted when reading the code.
- ""Enhance sysfs handling for memory hotplug in weighted interleave"
from Rakie Kim "enhances the weighted interleave policy in the memory
management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug
support". Fixes things on error paths which we are unlikely to hit.
- "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
from SeongJae Park introduces new DAMOS quota goal metrics which
eliminate the manual tuning which is required when utilizing DAMON
for memory tiering.
- "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
provides cleanups and small efficiency improvements which Baoquan
found via code inspection.
- "vmscan: enforce mems_effective during demotion" from Gregory Price
changes reclaim to respect cpuset.mems_effective during demotion when
possible. because presently, reclaim explicitly ignores
cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated.
This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently.
- "Clean up split_huge_pmd_locked() and remove unnecessary folio
pointers" from Gavin Guo provides minor cleanups and efficiency gains
in in the huge page splitting and migrating code.
- "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
for `struct mem_cgroup', yielding improved memory utilization.
- "add max arg to swappiness in memory.reclaim and lru_gen" from
Zhongkun He adds a new "max" argument to the "swappiness=" argument
for memory.reclaim MGLRU's lru_gen.
This directs proactive reclaim to reclaim from only anon folios
rather than file-backed folios.
- "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
first step on the path to permitting the kernel to maintain existing
VMs while replacing the host kernel via file-based kexec. At this
time only memblock's reserve_mem is preserved.
- "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
and uses a smarter way of looping over a pfn range. By skipping
ranges of invalid pfns.
- "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
when a task is pinned a single NUMA mode.
Dramatic performance benefits were seen in some real world cases.
- "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
Garg addresses a warning which occurs during memory compaction when
using JFS.
- "move all VMA allocation, freeing and duplication logic to mm" from
Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
appropriate mm/vma.c.
- "mm, swap: clean up swap cache mapping helper" from Kairui Song
provides code consolidation and cleanups related to the folio_index()
function.
- "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.
- "memcg: Fix test_memcg_min/low test failures" from Waiman Long
addresses some bogus failures which are being reported by the
test_memcontrol selftest.
- "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
Stoakes commences the deprecation of file_operations.mmap() in favor
of the new file_operations.mmap_prepare().
The latter is more restrictive and prevents drivers from messing with
things in ways which, amongst other problems, may defeat VMA merging.
- "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
the per-cpu memcg charge cache from the objcg's one.
This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- "mm/damon: minor fixups and improvements for code, tests, and
documents" from SeongJae Park is yet another batch of miscellaneous
DAMON changes. Fix and improve minor problems in code, tests and
documents.
- "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
stats to be irq safe. Another step along the way to making memcg
charging and stats updates NMI-safe, a BPF requirement.
- "Let unmap_hugepage_range() and several related functions take folio
instead of page" from Fan Ni provides folio conversions in the
hugetlb code.
* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
mm: pcp: increase pcp->free_count threshold to trigger free_high
mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
mm/hugetlb: pass folio instead of page to unmap_ref_private()
memcg: objcg stock trylock without irq disabling
memcg: no stock lock for cpu hot-unplug
memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
memcg: make count_memcg_events re-entrant safe against irqs
memcg: make mod_memcg_state re-entrant safe against irqs
memcg: move preempt disable to callers of memcg_rstat_updated
memcg: memcg_rstat_updated re-entrant safe against irqs
mm: khugepaged: decouple SHMEM and file folios' collapse
selftests/eventfd: correct test name and improve messages
alloc_tag: check mem_profiling_support in alloc_tag_init
Docs/damon: update titles and brief introductions to explain DAMOS
selftests/damon/_damon_sysfs: read tried regions directories in order
mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
...
The default idle selection policy doesn't properly handle the case where
@prev_cpu is not part of the task's allowed CPUs.
In this situation, it may return an idle CPU that is not usable by the
task, breaking the assumption that the returned CPU must always be
within the allowed cpumask, causing inefficiencies or even stalls in
certain cases.
This issue can arise in the following cases:
- The task's affinity may have changed by the time the function is
invoked, especially now that the idle selection logic can be used
from multiple contexts (i.e., BPF test_run call).
- The BPF scheduler may provide a @prev_cpu that is not part of the
allowed mask, either unintentionally or as a placement hint. In fact
@prev_cpu may not necessarily refer to the CPU the task last ran on,
but it can also be considered as a target CPU that the scheduler
wishes to use for the task.
Therefore, enforce the right behavior by always checking whether
@prev_cpu is in the allowed mask, when using scx_bpf_select_cpu_and(),
and it's also usable by the task (@p->cpus_ptr). If it is not, try to
find a valid CPU nearby @prev_cpu, following the usual locality-aware
fallback path (SMT, LLC, node, allowed CPUs).
This ensures the returned CPU is always allowed, improving robustness to
affinity changes and invalid scheduler hints, while preserving locality
as much as possible.
Fixes: a730e3f7a4 ("sched_ext: idle: Consolidate default idle CPU selection kfuncs")
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Merge tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next
Pull bpf updates from Alexei Starovoitov:
- Fix and improve BTF deduplication of identical BTF types (Alan
Maguire and Andrii Nakryiko)
- Support up to 12 arguments in BPF trampoline on arm64 (Xu Kuohai and
Alexis Lothoré)
- Support load-acquire and store-release instructions in BPF JIT on
riscv64 (Andrea Parri)
- Fix uninitialized values in BPF_{CORE,PROBE}_READ macros (Anton
Protopopov)
- Streamline allowed helpers across program types (Feng Yang)
- Support atomic update for hashtab of BPF maps (Hou Tao)
- Implement json output for BPF helpers (Ihor Solodrai)
- Several s390 JIT fixes (Ilya Leoshkevich)
- Various sockmap fixes (Jiayuan Chen)
- Support mmap of vmlinux BTF data (Lorenz Bauer)
- Support BPF rbtree traversal and list peeking (Martin KaFai Lau)
- Tests for sockmap/sockhash redirection (Michal Luczaj)
- Introduce kfuncs for memory reads into dynptrs (Mykyta Yatsenko)
- Add support for dma-buf iterators in BPF (T.J. Mercier)
- The verifier support for __bpf_trap() (Yonghong Song)
* tag 'bpf-next-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (135 commits)
bpf, arm64: Remove unused-but-set function and variable.
selftests/bpf: Add tests with stack ptr register in conditional jmp
bpf: Do not include stack ptr register in precision backtracking bookkeeping
selftests/bpf: enable many-args tests for arm64
bpf, arm64: Support up to 12 function arguments
bpf: Check rcu_read_lock_trace_held() in bpf_map_lookup_percpu_elem()
bpf: Avoid __bpf_prog_ret0_warn when jit fails
bpftool: Add support for custom BTF path in prog load/loadall
selftests/bpf: Add unit tests with __bpf_trap() kfunc
bpf: Warn with __bpf_trap() kfunc maybe due to uninitialized variable
bpf: Remove special_kfunc_set from verifier
selftests/bpf: Add test for open coded dmabuf_iter
selftests/bpf: Add test for dmabuf_iter
bpf: Add open coded dmabuf iterator
bpf: Add dmabuf iterator
dma-buf: Rename debugfs symbols
bpf: Fix error return value in bpf_copy_from_user_dynptr
libbpf: Use mmap to parse vmlinux BTF from sysfs
selftests: bpf: Add a test for mmapable vmlinux BTF
btf: Allow mmap of vmlinux btf
...
- More in-kernel idle CPU selection improvements. Expand topology awareness
coverage add scx_bpf_select_cpu_and() to allow more flexibility. The idle
CPU selection kfuncs can now be called from unlocked contexts too.
- A bunch of reorganization changes to lay the foundation for multiple
hierarchical scheduler support. This isn't ready yet and the included
changes don't make meaningful behavior differences. One notable change is
replacing some static_key tests with dynamic tests as the test results may
differ depending on the scheduler instance. This isn't expected to cause
meaningful performance difference.
- Other minor and doc updates.
- There were multiple patches in for-6.15-fixes which conflicted with
changes in for-6.16. for-6.15-fixes were pulled three times into for-6.16
to resolve the conflicts.
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Merge tag 'sched_ext-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext
Pull sched_ext updates from Tejun Heo:
- More in-kernel idle CPU selection improvements. Expand topology
awareness coverage add scx_bpf_select_cpu_and() to allow more
flexibility. The idle CPU selection kfuncs can now be called from
unlocked contexts too.
- A bunch of reorganization changes to lay the foundation for multiple
hierarchical scheduler support. This isn't ready yet and the included
changes don't make meaningful behavior differences. One notable
change is replacing some static_key tests with dynamic tests as the
test results may differ depending on the scheduler instance. This
isn't expected to cause meaningful performance difference.
- Other minor and doc updates.
- There were multiple patches in for-6.15-fixes which conflicted with
changes in for-6.16. for-6.15-fixes were pulled three times into
for-6.16 to resolve the conflicts.
* tag 'sched_ext-for-6.16' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: (49 commits)
sched_ext: Call ops.update_idle() after updating builtin idle bits
sched_ext, docs: convert mentions of "CFS" to "fair-class scheduler"
selftests/sched_ext: Update test enq_select_cpu_fails
sched_ext: idle: Consolidate default idle CPU selection kfuncs
selftests/sched_ext: Add test for scx_bpf_select_cpu_and() via test_run
sched_ext: idle: Allow scx_bpf_select_cpu_and() from unlocked context
sched_ext: idle: Validate locking correctness in scx_bpf_select_cpu_and()
sched_ext: Make scx_kf_allowed_if_unlocked() available outside ext.c
sched_ext, docs: add label
sched_ext: Explain the temporary situation around scx_root dereferences
sched_ext: Add @sch to SCX_CALL_OP*()
sched_ext: Cleanup [__]scx_exit/error*()
sched_ext: Add @sch to SCX_CALL_OP*()
sched_ext: Clean up scx_root usages
Documentation: scheduler: Changed lowercase acronyms to uppercase
sched_ext: Avoid NULL scx_root deref in __scx_exit()
sched_ext: Add RCU protection to scx_root in DSQ iterator
sched_ext: Clean up SCX_EXIT_NONE handling in scx_disable_workfn()
sched_ext: Move disable machinery into scx_sched
sched_ext: Move event_stats_cpu into scx_sched
...
