Patch series "mm/damon: documentation and comment fixes".
This patch (of 3):
damon_set_attrs() updates next_aggregation_sis and next_ops_update_sis for
online attrs updates, but it does not update next_intervals_tune_sis
there.
This can look like a missing update when reading damon_set_attrs() alone,
while next_intervals_tune_sis is actually updated in kdamond_fn().
Add a short comment to make this explicit.
Link: https://lore.kernel.org/20260520012104.93602-1-sj@kernel.org
Link: https://lore.kernel.org/20260520012104.93602-2-sj@kernel.org
Suggested-by: SeongJae Park <sj@kernel.org>
Signed-off-by: niecheng <niecheng1@uniontech.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Sakurai Shun <ssh1326@icloud.com>
Cc: Zenghui Yu <zenghui.yu@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fix these two typos:
1. approporiately -> appropriately
2. presure -> pressure
Link: https://lore.kernel.org/20260520051751.74396-1-leon.hwang@linux.dev
Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Leon Hwang <leon.hwang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, DAMON virtual address operations use mmap_read_lock during page
table walks, which can cause unnecessary contention under high
concurrency.
Introduce damon_va_walk_page_range() to first attempt acquiring a per-vma
lock. If the VMA is found and the range is fully contained within it, the
page table walk proceeds with the per-vma lock instead of mmap_read_lock.
This optimization is expected to be particularly effective for
damon_va_young() and damon_va_mkold(), which are frequently called and
typically operate within a single VMA.
Link: https://lore.kernel.org/20260512151523.2092638-1-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Nanyong Sun <sunnanyong@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
__page_handle_poison() used drain_all_pages() instead of
zone_pcp_disable() because dissolve_free_hugetlb_folio() could restore HVO
vmemmap pages and decrement hugetlb_optimize_vmemmap_key. That static key
update took cpu_hotplug_lock through static_key_slow_dec(), while
zone_pcp_disable() holds pcp_batch_high_lock. CPU hotplug takes the locks
in the opposite order through page_alloc_cpu_online/dead(), so the
combination could deadlock.
That dependency no longer exists. Commit da3e2d1ca4 ("mm/hugetlb:
remove hugetlb_optimize_vmemmap_key static key") removed the HVO static
key and the static_branch_dec() from hugetlb_vmemmap_restore_folio(). The
dissolve_free_hugetlb_folio() path no longer reaches
static_key_slow_dec().
Use zone_pcp_disable() again while dissolving the hugetlb folio and taking
the target page off the buddy allocator. This prevents the drained PCP
lists from being refilled before take_page_off_buddy() runs, making the
page isolation deterministic.
Link: https://lore.kernel.org/20260514085754.84097-1-kaitao.cheng@linux.dev
Signed-off-by: Kaitao Cheng <chengkaitao@kylinos.cn>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If __add_memory_block() fails at xa_store() (under memory pressure for
example), device_unregister() is called, which eventually triggers
memory_block_release() with mem->altmap still set, causing a
WARN_ON(mem->altmap). This was triggered by modifying virtio-mem driver.
Fix this by delaying the assignment of mem->altmap until after
__add_memory_block() has succeeded.
Link: https://lore.kernel.org/20260514092657.3057141-1-georgi.djakov@oss.qualcomm.com
Fixes: 1a8c64e110 ("mm/memory_hotplug: embed vmem_altmap details in memory block")
Signed-off-by: Georgi Djakov <georgi.djakov@oss.qualcomm.com>
Acked-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Richard Cheng <icheng@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Georgi Djakov <djakov@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce a new test case "vrealloc_test" that exercises the vrealloc()
shrink and in-place grow paths:
- Grow beyond allocated pages (triggers full reallocation).
- Shrink crossing a page boundary (frees tail pages).
- Shrink within the same page (no page freeing).
- Grow within the already allocated page count (in-place).
Data integrity is validated after each realloc step by checking that the
first byte of the original allocation is preserved.
The test is gated behind run_test_mask bit 12 (id 4096).
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-5-70b96ee3e9c9@zohomail.in
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When vrealloc() shrinks an allocation and the new size crosses a page
boundary, unmap and free the tail pages that are no longer needed. This
reclaims physical memory that was previously wasted for the lifetime of
the allocation.
The heuristic is simple: always free when at least one full page becomes
unused. Huge page allocations (page_order > 0) are skipped, as partial
freeing would require splitting. Allocations with VM_FLUSH_RESET_PERMS
are also skipped, as their direct-map permissions must be reset before
pages are returned to the page allocator, which is handled by
vm_reset_perms() during vfree().
Additionally, allocations with VM_USERMAP are skipped because
remap_vmalloc_range_partial() validates mapping requests against the
unchanged vm->size; freeing tail pages would cause vmalloc_to_page() to
return NULL for the unmapped range.
To protect concurrent readers, the shrink path uses Node lock to
synchronize before freeing the pages.
Finally, we notify kmemleak of the reduced allocation size using
kmemleak_free_part() to prevent the kmemleak scanner from faulting on the
newly unmapped virtual addresses.
The virtual address reservation (vm->size / vmap_area) is intentionally
kept unchanged, preserving the address for potential future grow-in-place
support.
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-4-70b96ee3e9c9@zohomail.in
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
Suggested-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
For VM_ALLOC areas in vread_iter(), derive the vm area size from
vm->nr_pages rather than get_vm_area_size().
Only VM_ALLOC areas are subject to vrealloc() shrinking, which frees pages
without reducing the virtual reservation size. Switch to using
vm->nr_pages for VM_ALLOC areas so the reader remains correct once shrink
support is added. Other mapping types (vmap, ioremap) do not initialize
nr_pages and will continue using get_vm_area_size().
[shivamkalra98@zohomail.in: add an nr_pages check]
Link: https://lore.kernel.org/aff47da5-4fd5-481d-be18-e1eb99639490@zohomail.in
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-3-70b96ee3e9c9@zohomail.in
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Update the grow-in-place check in vrealloc() to compare the requested size
against the actual physical page count (vm->nr_pages) rather than the
virtual area size (alloced_size, derived from get_vm_area_size()).
Currently both values are equivalent, but the upcoming vrealloc() shrink
functionality will free pages without reducing the virtual reservation
size. After such a shrink, the old alloced_size-based comparison would
incorrectly allow a grow-in-place operation to succeed and attempt to
access freed pages. Switch to vm->nr_pages now so the check remains
correct once shrink support is added.
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-2-70b96ee3e9c9@zohomail.in
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/vmalloc: free unused pages on vrealloc() shrink", v14.
This series implements the TODO in vrealloc() to unmap and free unused
pages when shrinking across a page boundary.
Problem:
When vrealloc() shrinks an allocation, it updates bookkeeping
(requested_size, KASAN shadow) but does not free the underlying physical
pages. This wastes memory for the lifetime of the allocation.
Solution:
- Patch 1: Extracts a vm_area_free_pages(vm, start_idx, end_idx) helper
from vfree() that frees a range of pages with memcg and nr_vmalloc_pages
accounting. Freed page pointers are set to NULL to prevent stale
references.
- Patch 2: Update the grow-in-place check in vrealloc() to compare the
requested size against the actual physical page count (vm->nr_pages)
rather than the virtual area sizes. This is a prerequisite for shrinking.
- Patch 3: For VM_ALLOC areas in vread_iter(), derive the vm area size
from vm->nr_pages rather than get_vm_area_size(), which would
overestimate the mapped range after a shrink. Other mapping types
(vmap, ioremap) don't set nr_pages and keep using get_vm_area_size().
- Patch 4: Uses the helper to free tail pages when vrealloc() shrinks
across a page boundary.
- Patch 5: Adds a vrealloc test case to lib/test_vmalloc that exercises
grow-realloc, shrink-across-boundary, shrink-within-page, and
grow-in-place paths.
The virtual address reservation is kept intact to preserve the range for
potential future grow-in-place support. A concrete user is the Rust
binder driver's KVVec::shrink_to [1], which performs explicit vrealloc()
shrinks for memory reclamation.
This patch (of 5):
Extract page freeing and NR_VMALLOC stat accounting from vfree() into a
reusable vm_area_free_pages() helper. The helper operates on a range
[start_idx, end_idx) of pages from a vm_struct, making it suitable for
both full free (vfree) and partial free (upcoming vrealloc shrink).
Freed page pointers in vm->pages[] are set to NULL to prevent stale
references when the vm_struct outlives the free (as in vrealloc shrink).
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-0-70b96ee3e9c9@zohomail.in
Link: https://lore.kernel.org/20260519-vmalloc-shrink-v14-1-70b96ee3e9c9@zohomail.in
Link: https://lore.kernel.org/all/20260216-binder-shrink-vec-v3-v6-0-ece8e8593e53@zohomail.in/ [1]
Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Find and set the memcg_id for damon_filter from the user-passed memory
cgroup path when updating the DAMON input parameters.
Link: https://lore.kernel.org/20260518234119.97569-27-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The next commit will need to find the memcg id from the user-passed path
to the memory cgroup, from sysfs.c. memcg_path_to_id() is doing that, but
defined in sysfs-schemes.c as a static function. Move the function to
sysfs-common.c and mark it as non-static, so that the next commit can
reuse the function.
Link: https://lore.kernel.org/20260518234119.97569-26-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce a new DAMON sysfs file for letting users setup the target memory
cgroup of the belonging memory cgroup attribute monitoring. The file is
named 'path', located under the probe filter directory. Users can set the
target memory cgroup by writing the path to the memory cgroup from the
cgroup mount point to the file.
Link: https://lore.kernel.org/20260518234119.97569-25-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Implement the support of DAMON_FILTER_TYPE_MEMCG on the DAMON operation
set implementation for the physical address space.
Link: https://lore.kernel.org/20260518234119.97569-24-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Belonging memory cgoup is another data attribute that can be useful to
monitor. Introduce a new DAMON filter type, namely
DAMON_FILTER_TYPE_MEMCG, for monitoring of this attribute.
Link: https://lore.kernel.org/20260518234119.97569-23-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Implement a sysfs directory for showing the per-region probe hit counts.
It is named 'probes/' and located under the DAMOS tried region directory.
Link: https://lore.kernel.org/20260518234119.97569-16-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add user-installed data probes to DAMON core API parameters, so that user
inputs for data probes are passed to DAMON core.
Link: https://lore.kernel.org/20260518234119.97569-15-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Implement a sysfs directory for letting the users to configure each data
probe filter.
Link: https://lore.kernel.org/20260518234119.97569-13-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Implement sysfs directory that can be used by the users to install data
probes.
Link: https://lore.kernel.org/20260518234119.97569-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Implement the data attributes monitoring execution. Update kdamond to
invoke the probes application callback, and reset the aggregated number of
per-region per-probe positive samples for every aggregation interval.
Link: https://lore.kernel.org/20260518234119.97569-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Extend damon_operations struct with a new callback, namely apply_probes.
The callback will be invoked for data attributes monitoring. More
specifically, the callback will apply damon_probe objects to each region
and update the per-region per-probe counters for the number of encountered
probe-positive samples.
Link: https://lore.kernel.org/20260518234119.97569-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add an array for the per-region per-probe positive samples count. For
simple and efficient implementation, add a limit to the number of data
probes and set the array to support only the limited number of counters.
Link: https://lore.kernel.org/20260518234119.97569-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Define a data structure for constructing damon_probe's attributes check,
namely damon_filter. It is very similar to damos_filter but works only
for monitoring purposes. Also embed that into damon_probe, implement
essential handling of the link, with fundamental helpers.
Link: https://lore.kernel.org/20260518234119.97569-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Let damon_probe objects be able to be installed on a given damon_ctx, by
adding a linked list header for storing the objects. Add initialization
and cleanup of the new field with helper functions, too.
Link: https://lore.kernel.org/20260518234119.97569-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/damon: introduce data attributes monitoring".
TL; DR
======
Extend DAMON for monitoring general data attributes other than accesses.
The short term motivation is lightweight page type (e.g., belonging
cgroup) aware monitoring. In long term, this will help extending DAMON
for multiple access events capture primitives (e.g., page faults and PMU)
and eventually pivotting DAMON to a "Data Attributes Monitoring and
Operations eNgine" in long term.
Background: High Cost of Page Level Properties Monitoring
=========================================================
DAMON is initially introduced as a Data Access MONitor. It has been
extended for not only access monitoring but also data access-aware system
operations (DAMOS). But still the monitoring part is only for data
accesses.
Data access patterns is good information, but some users need more
holistic views. Particularly, users want to show the access pattern
information together with the types of the memory. For example, users who
work for making huge pages efficiently want to know how much of
DAMON-found hot/cold regions are backed by huge pages. Users who run
multiple workloads with different cgroups want to know how much of
DAMON-found hot/cold regions belong to specific cgroups.
For the user demand, we developed a DAMOS extension for page level
properties based monitoring [1], which has landed on 6.14. Using the
feature, users can inform the page level data properties that they are
interested in, in a flexible format that uses DAMOS filters. Then, DAMON
applies the filters to each folio of the entire DAMON region and lets
users know how many bytes of memory in each DAMON region passed the given
filters.
This gives page level detailed and deterministic information to users.
But, because the operation is done at page level, the overhead is
proportional to the memory size. It was useful for test or debugging
purposes on a small number of machines. But it was obviously too heavy to
be enabled always on all machines running the real user workloads. For
real world workloads, it was recommended to use the feature with
user-space controlled sampling approaches. For example, users could do
the page level monitoring only once per hour, on randomly selected one
percent of machines of their fleet. If the runtime and the size of the
fleet is long and big enough, it should provide statistically meaningful
data.
But users are too busy to implement such controls on their own.
Data Attributes Monitoring
==========================
Extend DAMON to monitor not only data accesses, but also general data
attributes. Do the extension while keeping the main promise of DAMON, the
bounded and best-effort minimum overhead.
Allow users to specify what data attributes in addition to the data access
they want to monitor. Users can install one 'data probe' per data
attribute of their interest for this purpose. The 'data probe' should be
able to be applied to any memory, and determine if the given memory has
the appropriate data attribute. E.g., if memory of physical address 42
belongs to cgroup A. Each 'data probe' is configured with filters that
are very similar to the DAMOS filters.
When DAMON checks if each sampling address memory of each region is
accessed since the last check, it applies data probes if registered. Same
to the number of access check-positive samples accounting (nr_accesses),
it accounts the number of each data probe-positive samples in another
per-region counters array, namely 'probe_hits'. When DAMON resets
nr_accesses every aggregation interval, it resets 'probe_hits' together.
Users can read 'probe_hits' just before the values are reset. In this
way, users can know how many hot/cold memory regions have data attributes
of their interest. E.g., 30 percent of this system's hot memory is
belonging to cgroup A, and 80 percent of the cgroup A-belonging hot memory
is backed by huge pages.
Patches Sequence
================
First eight patches implement the core feature, interface and the working
support. Patch 1 introduces data probe data structure, namely
damon_probe. Patch 2 extends damon_ctx for installing data probes. Patch
3 introduces another data structure for filters of each data probe, namely
damon_filter. Patch 4 updates damon_ctx commit function to handle the
probes. Patch 5 extends damon_region for the per-region per-probe
positive samples counter, namely probe_hits. Patch 6 extends
damon_operations for applying probes on the underlying DAMON operations
implementation. Patch 7 updates kdamond_fn() to invoke the probes
applying callback. Patch 8 finally implements the probes support on paddr
ops.
Ten changes for user interface (patches 9-18) come next. Patches 9-13
implements sysfs directories and files for setting data probes, namely
probes directory, probe directory, filters directory, filter directory and
filter directory internal files, respectively. Patch 14 connects the user
inputs that are made via the sysfs files to DAMON core. Following three
patches (patches 15-17) implement sysfs directories and files for showing
the probe_hits to users, namely probes directory, probe directory and hits
files, respectively. Patch 18 introduces a new tracepoint for showing the
probe_hits via tracefs.
Patch 19 adds a selftest for the sysfs files.
Patches 20 and 21 documents the design and usage of the new feature,
respectively.
Seven additional patches (patches 22-28) for monitoring belonging memory
cgroup follow. Depending on the feedback, this part might be separated to
another series in future. Patch 22 defines the DAMON filter type for the
new attribute, namely DAMON_FILTER_TYPE_MEMCG. Patch 23 add the support
on paddr ops. Patch 24 updates the sysfs interface for setup of the
target memcg. Patch 25 move code for easy reuse of the filter target
memcg setup. Patch 26 connects the user input to the core layer.
Finally, patches 27 and 28 update the design and usage documents for the
memcg attribute monitoring support.
Discussion
==========
This allows the page properties monitoring with overhead that is low
enough to be enabled always on real world workloads. Because the sampling
time for access check is reused for data attributes check, the
upper-bounded and best-effort minimum overhead of DAMON is kept. Because
the sampling memory for access check is reused for data attributes check,
additional overhead is minimum.
Still DAMOS-based page level properties monitoring should be useful,
because it provides a deterministic page level information. When in doubt
of the sampling based information, running DAMOS-based one together and
comparing the results would be useful, for debugging and tuning.
Future Works: Mid Term
========================
This version of implementation is limiting the maximum number of data
probes to four. I will try to find a way to remove the limit in future.
I personally think it should be enough for common use cases, though, and
therefore not giving high priority at the moment.
Future Works: Long Term
=======================
There are user requests for extending DAMON with detailed access
information, for example, per-CPUs/threads/read/writes monitoring. For
that, I was working [2] on extending DAMON to use page fault events as
another access check primitives, and making the infrastructure flexible
for future use of yet another access check primitive. Actually there is
another ongoing work [3] for extending DAMON with PMU events. The
motivation of the work is reducing the overhead, though.
In my work [2], I was introducing a new interface for access sampling
primitives control. Now I think this data probe interface can be used for
that, too. That is, data access becomes just one type of data attribute.
Also, pg_idle-confirmed access, page fault-confirmed access, and PMU
event-confirmed access will be different types of data attributes.
The regions adjustment mechanism is currently working based on the access
information. That's because DAMON is designed for data access monitoring.
That is, data access information is the primary interest, and therefore
DAMON adjusts regions in a way that can best-present the information.
Once data access becomes just one of data attributes, there is no reason
to think data access that special. There might be some users not
interested in access at all but want to know the location of memory of
specific type. Data probes interface will allow doing that. Further, we
could extend the interface to let users set any data attribute as the
'primary' attribute. Then, DAMON will split and merge regions in a way
that can best-present the 'primary' attributes.
DAMOS will also be extended, to specify targets based on not only the data
access pattern, but all user-registered data attributes. From this stage,
we may be able to call DAMON as a "Data Attributes Monitoring and
Operations eNgine".
This patch (of 28):
Introduce a data structure for data attribute probe. It is just a linked
list header at this step. It will be extended in a way that it can
determine if a given memory has a specific data attribute.
Link: https://lore.kernel.org/20260518234119.97569-1-sj@kernel.org
Link: https://lore.kernel.org/20260518234119.97569-2-sj@kernel.org
Link: https://lore.kernel.org/20250106193401.109161-1-sj@kernel.org [1]
Link: https://lore.kernel.org/20251208062943.68824-1-sj@kernel.org/ [2]
Link: https://lore.kernel.org/20260423004211.7037-1-akinobu.mita@gmail.com [3]
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Use -ENOENT return value to distinguish "not a hugetlb page" from "hugetlb
handled", instead of carrying an extra output parameter.
Link: https://lore.kernel.org/20260515020144.164941-1-ye.liu@linux.dev
Signed-off-by: Ye Liu <liuye@kylinos.cn>
Suggested-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Oscar Salvador (SUSE) <osalvador@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
By allocating one additional bit in the swap table entry's flags field
alongside the count, we can store the zeromap inline
For 64 bit systems, zeromap will store in the swap table, avoiding zeromap
allocation. It reduces the allocated memory. That is the happy path.
For certain 32-bit archs, there might not be enough bits in the swap table
to contain both PFN and flags. Therefore, conditionally let each cluster
have a zeromap field at build time, and use that instead. If the swapfile
cluster is not fully used, it will still save memory for zeromap. The
empty cluster does not allocate a zeromap. In the worst case, all cluster
are fully populated. We will use memory similar to the previous zeromap
implementation.
A few macros were moved to different headers for build time struct
definition.
[akpm@linux-foundation.org: swap_cluster_alloc_table(): remove unused local `ret]
[akpm@linux-foundation.org: fix unused label `err_free']
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-12-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Youngjun Park <youngjun.park@lge.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now all swap cgroup records are stored in the swap cluster directly, the
static array is no longer needed.
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-11-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Drop the usage of the swap_cgroup_ctrl, and use the dynamic cluster table
instead.
The per-cluster memcg table is 1024 / 512 bytes on most archs, and does
not need RCU protection: the cgroup data is only read and written under
the cluster lock. That keeps things simple, lets the allocation use plain
kmalloc with immediate kfree (no deferred free), and keeps fragmentation
acceptable.
[akpm@linux-foundation.org: memcgv1: don't compile swap functions when CONFIG_SWAP=n]
Link: https://lore.kernel.org/202605281711.bSeZlErK-lkp@intel.com
[akpm@linux-foundation.org: fix CONFIG_SWAP=n build]
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-10-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Swap cluster table management is spread across several narrow helpers. As
a result, the allocation and fallback sequences are open-coded in multiple
places.
A few more per-cluster tables will be added soon, so avoid duplicating
these sequences per table type. Fold the existing pairs into
cluster-oriented helpers, and rename for consistency.
No functional change, only a few sanity checks are slightly adjusted.
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-9-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Instead of checking the cgroup private ID during page table walk in
swap_pte_batch(), move the memcg lookup into __swap_cache_add_check()
under the cluster lock.
The first pre-alloc check is speculative and skips the memcg check since
the post-alloc stable check ensures all slots covered by the folio belong
to the same memcg. It is very rare for contiguous and aligned entries
across a contiguous region of a page table of the same process or shmem
mapping to belong to different memcgs.
This also prepares for recording the memcg info in the cluster's table.
Also make the order check and fallback more compact.
There should be no user-observable behavior change.
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-8-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Instead of requiring the caller to ensure all slots are in the same memcg,
make the function handle different memcgs at once.
This is both a micro optimization and required for removing the memcg
lookup in the page table layer, so it can be unified at the swap layer.
We are not removing the memcg lookup in the page table in this commit. It
has to be done after the memcg lookup is deferred to the swap layer.
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-7-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The cgroup v1 swap helpers always operate on swap cache folios whose swap
entry is stable: the folio is locked and in the swap cache. There is no
need to pass the swap entry or page count as separate parameters when they
can be derived from the folio itself.
Simplify the redundant parameters and add sanity checks to document the
required preconditions.
Also rename memcg1_swapout to __memcg1_swapout to indicate it requires
special calling context: the folio must be isolated and dying, and the
call must be made with interrupts disabled.
No functional change.
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-6-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now that direct large order allocation is supported in the swap cache,
both anon and shmem can use it instead of implementing their own methods.
This unifies the fallback and swap cache check, which also reduces the
TOCTOU race window of swap cache state: previously, high order swapin
required checking swap cache states first, then allocating and falling
back separately. Now all these steps happen in the same compact loop.
Order fallback and statistics are also unified, callers just need to check
and pass the acceptable order bitmask.
There is basically no behavior change. This only makes things more
unified and prepares for later commits. Cgroup and zero map checks can
also be moved into the compact loop, further reducing race windows and
redundancy
Link: https://lore.kernel.org/20260517-swap-table-p4-v5-5-88ae43e064c7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Youngjun Park <youngjun.park@lge.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
