<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/git/stable/linux.git/mm/memcontrol.c, branch linux-rolling-lts</title>
<subtitle>Linux kernel stable tree</subtitle>
<id>https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/atom?h=linux-rolling-lts</id>
<link rel='self' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/atom?h=linux-rolling-lts'/>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/'/>
<updated>2026-09-07T15:22:22+00:00</updated>
<entry>
<title>mm: memcontrol: update state_local when flushing NMI stats</title>
<updated>2026-09-07T15:22:22+00:00</updated>
<author>
<name>Guopeng Zhang</name>
<email>zhangguopeng@kylinos.cn</email>
</author>
<published>2026-07-13T08:50:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5d866086d5f8dfc44e5e8665940f7d1468ca8b9a'/>
<id>urn:sha1:5d866086d5f8dfc44e5e8665940f7d1468ca8b9a</id>
<content type='text'>
commit 72f522bbf473f03a77e83547b677dc1505c5d41a upstream.

flush_nmi_stats() updates state[] for kmem and slab counters but leaves
the corresponding state_local[] counters unchanged.  Local kmem and slab
statistics therefore miss updates collected through the NMI-safe atomic
path.

Update state_local[] together with state[].

Link: https://lore.kernel.org/20260713085053.2916813-1-guopeng.zhang@linux.dev
Fixes: 940b01fc8dc1 ("memcg: nmi safe memcg stats for specific archs")
Signed-off-by: Guopeng Zhang &lt;zhangguopeng@kylinos.cn&gt;
Acked-by: Tao Cui &lt;cuitao@kylinos.cn&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Acked-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Cc: Alexandre Ghiti &lt;alex@ghiti.fr&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: Vlastimil Babka &lt;vbabka@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm: memcg: stop reclaim when a limit update is superseded</title>
<updated>2026-09-07T15:22:22+00:00</updated>
<author>
<name>Guopeng Zhang</name>
<email>zhangguopeng@kylinos.cn</email>
</author>
<published>2026-07-24T02:18:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=95d87030cae7764805aa7c621c52871139297cb0'/>
<id>urn:sha1:95d87030cae7764805aa7c621c52871139297cb0</id>
<content type='text'>
commit 9477820c63cbf4d97114238f3d1ff10dfd6bee3f upstream.

kernfs serializes file operations only per open file, so separate open
files can update the same memory.high or memory.max file concurrently.
Both handlers store the new limit before synchronous reclaim, but continue
to use the writer's local target in the reclaim loop.  If another writer
raises or removes the limit, the first writer can continue reclaiming
toward a stale target.

For memory.max, this can leave the writer looping indefinitely once
reclaim retries are exhausted.  The OOM path sees sufficient margin under
the current limit and returns true without killing, while the writer still
compares usage against its stale target and records another OOM event.

Check the current limit at the start of each reclaim iteration and stop if
it no longer matches the writer's target.

Reproducer:

Populate a cgroup with anonymous memory and disable swapping.  Lower
memory.max from one open file, then restore it to "max" through another
open file after the new limit becomes visible.

Without the patch, the first writer remains blocked and repeatedly
increments the OOM event counter.  With the patch, it returns normally.

This was not motivated by a reported production workload.  We found it
through automated randomized testing for our cgroup observability work
and reduced it to the reproducer above.

Link: https://lore.kernel.org/20260724021805.1234583-1-guopeng.zhang@linux.dev
Fixes: 8c8c383c04f6 ("mm: memcontrol: try harder to set a new memory.high")
Fixes: b6e6edcfa405 ("mm: memcontrol: reclaim and OOM kill when shrinking memory.max below usage")
Signed-off-by: Guopeng Zhang &lt;zhangguopeng@kylinos.cn&gt;
Acked-by: Tao Cui &lt;cuitao@kylinos.cn&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm: memcg-v1: fix memsw and TCP failcnt accounting</title>
<updated>2026-09-07T15:22:22+00:00</updated>
<author>
<name>Guopeng Zhang</name>
<email>zhangguopeng@kylinos.cn</email>
</author>
<published>2026-08-11T03:08:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=680b93894ddf6cc0f5b8bc5bd57a67a640460e3b'/>
<id>urn:sha1:680b93894ddf6cc0f5b8bc5bd57a67a640460e3b</id>
<content type='text'>
commit 92192e9c5ee07efc657d3654bc264081fb0aa01b upstream.

Commit 0e2759afcaf9 ("page_counter: track failcnt only for legacy
cgroups") made failcnt accounting conditional on track_failcnt.  It
enabled the flag for memcg-&gt;memory, but not for memcg-&gt;memsw or
memcg-&gt;tcpmem.

Consequently, memory.memsw.failcnt remains zero when the memory+swap limit
is hit.  memory.kmem.tcp.limit_in_bytes still sets memcg-&gt;tcpmem.max, but
TCP charge failures are not reflected in memory.kmem.tcp.failcnt.

Enable failcnt accounting for both v1 counters.

To reproduce memory.memsw.failcnt:

    CG=/sys/fs/cgroup/memory/memsw-test
    LIMIT=33554432
    mkdir "$CG"
    echo "$LIMIT" &gt; "$CG/memory.limit_in_bytes"
    echo "$LIMIT" &gt; "$CG/memory.memsw.limit_in_bytes"

Start a child process in the cgroup and make it allocate and touch 96 MiB
of memory, causing a memcg OOM.

    cat "$CG/memory.memsw.failcnt"

Without the patch, memory.memsw.failcnt is 0. With the patch,
memory.memsw.failcnt is greater than 0.

To reproduce memory.kmem.tcp.failcnt:

    CG=/sys/fs/cgroup/memory/tcpmem-test
    LIMIT=65536
    mkdir "$CG"
    echo "$LIMIT" &gt; "$CG/memory.kmem.tcp.limit_in_bytes"

Start a child process in the cgroup, create a TCP socket, and reserve
1 MiB of socket memory with SO_RESERVE_MEM. The reservation fails with
ENOMEM.

    cat "$CG/memory.kmem.tcp.failcnt"

Without the patch, memory.kmem.tcp.failcnt is 0.  With the patch,
memory.kmem.tcp.failcnt is greater than 0.

Link: https://lore.kernel.org/20260811030843.109104-1-guopeng.zhang@linux.dev
Closes: https://sashiko.dev/#/patchset/20260810074247.52747-1-guopeng.zhang@linux.dev?part=1
Fixes: 0e2759afcaf9 ("page_counter: track failcnt only for legacy cgroups")
Signed-off-by: Guopeng Zhang &lt;zhangguopeng@kylinos.cn&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Reviewed-by: Tao Cui &lt;cuitao@kylinos.cn&gt;
Acked-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>memcg: use round-robin victim selection in refill_stock</title>
<updated>2026-06-19T11:44:08+00:00</updated>
<author>
<name>Shakeel Butt</name>
<email>shakeel.butt@linux.dev</email>
</author>
<published>2026-05-21T22:37:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=89bd8215e25aa6999cc51696da418e0d422bc5e0'/>
<id>urn:sha1:89bd8215e25aa6999cc51696da418e0d422bc5e0</id>
<content type='text'>
commit c0cafe24d3f6534294c4b2bc2d47734ff7cbd313 upstream.

Harry Yoo reported that get_random_u32_below() is not safe to call in the
nmi context and memcg charge draining can happen in nmi context.

More specifically get_random_u32_below() is neither reentrant- nor
NMI-safe: it acquires a per-cpu local_lock via local_lock_irqsave() on the
batched_entropy_u32 state.  An NMI that lands on a CPU mid-update of the
ChaCha batch state and recurses into the random subsystem would corrupt
that state.  The memcg_stock local_trylock prevents re-entry on the percpu
stock itself, but cannot protect an unrelated subsystem's per-cpu lock.

Replace the random pick with a per-cpu round-robin counter stored in
memcg_stock_pcp and serialized by the same local_trylock that already
guards cached[] and nr_pages[].  No atomics, no random calls, no extra
locks needed.

Link: https://lore.kernel.org/20260521223751.3794625-1-shakeel.butt@linux.dev
Fixes: f735eebe55f8f ("memcg: multi-memcg percpu charge cache")
Signed-off-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Reported-by: Harry Yoo &lt;harry@kernel.org&gt;
Closes: https://lore.kernel.org/4e20f643-6983-4b6e-b12d-c6c4eb20ae0c@kernel.org/
Acked-by: Harry Yoo (Oracle) &lt;harry@kernel.org&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm: memcontrol: propagate NMI slab stats to memcg vmstats</title>
<updated>2026-06-09T10:28:34+00:00</updated>
<author>
<name>Alexandre Ghiti</name>
<email>alex@ghiti.fr</email>
</author>
<published>2026-05-18T08:28:19+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=f1f0cdca932be50f278385574661822abb9ae326'/>
<id>urn:sha1:f1f0cdca932be50f278385574661822abb9ae326</id>
<content type='text'>
commit e16f17a9c5af50221184d1ef4be4056bf3c4209e upstream.

flush_nmi_stats() drains per-node NMI slab atomics into the per-node
lruvec_stats, but does not propagate them to the memcg-level vmstats.

For non NMI case, account_slab_nmi_safe() calls mod_memcg_lruvec_state()
which updates both per-node lruvec_stats and memcg-level vmstats, so
flush_nmi_stats() needs to flush to per-node lruvec_stats as well as
memcg-level vmstats.

So fix this by flushing to the memcg-level vmstats for NMI too.

Link: https://lore.kernel.org/20260518082830.599102-1-alex@ghiti.fr
Fixes: 940b01fc8dc1 ("memcg: nmi safe memcg stats for specific archs")
Signed-off-by: Alexandre Ghiti &lt;alex@ghiti.fr&gt;
Acked-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Reviewed-by: Harry Yoo (Oracle) &lt;harry@kernel.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>cgroup/rstat: validate cpu before css_rstat_cpu() access</title>
<updated>2026-06-01T15:51:03+00:00</updated>
<author>
<name>Qing Ming</name>
<email>a0yami@mailbox.org</email>
</author>
<published>2026-05-16T07:08:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6'/>
<id>urn:sha1:6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6</id>
<content type='text'>
[ Upstream commit 8817005efbdfdf5d4e4814cb5dc52b53d12917d7 ]

css_rstat_updated() is exposed as a BPF kfunc and accepts a
caller-provided cpu argument. The function uses cpu for per-cpu rstat
lookups without checking whether it refers to a valid possible CPU.

A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an
invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu ==
0x7fffffff triggers:

  UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9
  index 2147483647 is out of range for type 'long unsigned int [64]'
  Call Trace:
    css_rstat_updated
    bpf_iter_run_prog
    cgroup_iter_seq_show
    bpf_seq_read

Add cpu validation to the BPF-facing css_rstat_updated() kfunc and
move the common implementation to __css_rstat_updated() for in-kernel
callers.

Fixes: a319185be9f5 ("cgroup: bpf: enable bpf programs to integrate with rstat")
Signed-off-by: Qing Ming &lt;a0yami@mailbox.org&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>memcg: fix slab accounting in refill_obj_stock() trylock path</title>
<updated>2026-03-19T15:08:39+00:00</updated>
<author>
<name>Hao Li</name>
<email>hao.li@linux.dev</email>
</author>
<published>2026-02-26T11:51:37+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=146691daf293c5781a75e408043ee8891e60ae4a'/>
<id>urn:sha1:146691daf293c5781a75e408043ee8891e60ae4a</id>
<content type='text'>
commit dccd5ee2625d50239510bcd73ed78559005e00a3 upstream.

In the trylock path of refill_obj_stock(), mod_objcg_mlstate() should use
the real alloc/free bytes (i.e., nr_acct) for accounting, rather than
nr_bytes.

The user-visible impact is that the NR_SLAB_RECLAIMABLE_B and
NR_SLAB_UNRECLAIMABLE_B stats can end up being incorrect.

For example, if a user allocates a 6144-byte object, then before this
fix efill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=2048), even
though it should account for 6144 bytes (i.e., nr_acct).

When the user later frees the same object with kfree(),
refill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=6144).  This
ends up adding 6144 to the stats, but it should be applying -6144
(i.e., nr_acct) since the object is being freed.

Link: https://lkml.kernel.org/r/20260226115145.62903-1-hao.li@linux.dev
Fixes: 200577f69f29 ("memcg: objcg stock trylock without irq disabling")
Signed-off-by: Hao Li &lt;hao.li@linux.dev&gt;
Acked-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Acked-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Michal Hocko &lt;mhocko@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
</entry>
<entry>
<title>mm/vmscan: fix demotion targets checks in reclaim/demotion</title>
<updated>2026-03-04T12:21:29+00:00</updated>
<author>
<name>Bing Jiao</name>
<email>bingjiao@google.com</email>
</author>
<published>2026-01-14T20:53:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=e116e19c95845133a4f194dfad3678758d0b6689'/>
<id>urn:sha1:e116e19c95845133a4f194dfad3678758d0b6689</id>
<content type='text'>
[ Upstream commit 1aceed565ff172fc0331dd1d5e7e65139b711139 ]

Patch series "mm/vmscan: fix demotion targets checks in reclaim/demotion",
v9.

This patch series addresses two issues in demote_folio_list(),
can_demote(), and next_demotion_node() in reclaim/demotion.

1. demote_folio_list() and can_demote() do not correctly check
   demotion target against cpuset.mems_effective, which will cause (a)
   pages to be demoted to not-allowed nodes and (b) pages fail demotion
   even if the system still has allowed demotion nodes.

   Patch 1 fixes this bug by updating cpuset_node_allowed() and
   mem_cgroup_node_allowed() to return effective_mems, allowing directly
   logic-and operation against demotion targets.

2. next_demotion_node() returns a preferred demotion target, but it
   does not check the node against allowed nodes.

   Patch 2 ensures that next_demotion_node() filters against the allowed
   node mask and selects the closest demotion target to the source node.

This patch (of 2):

Fix two bugs in demote_folio_list() and can_demote() due to incorrect
demotion target checks against cpuset.mems_effective in reclaim/demotion.

Commit 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim")
introduces the cpuset.mems_effective check and applies it to can_demote().
However:

  1. It does not apply this check in demote_folio_list(), which leads
     to situations where pages are demoted to nodes that are
     explicitly excluded from the task's cpuset.mems.

  2. It checks only the nodes in the immediate next demotion hierarchy
     and does not check all allowed demotion targets in can_demote().
     This can cause pages to never be demoted if the nodes in the next
     demotion hierarchy are not set in mems_effective.

These bugs break resource isolation provided by cpuset.mems.  This is
visible from userspace because pages can either fail to be demoted
entirely or are demoted to nodes that are not allowed in multi-tier memory
systems.

To address these bugs, update cpuset_node_allowed() and
mem_cgroup_node_allowed() to return effective_mems, allowing directly
logic-and operation against demotion targets.  Also update can_demote()
and demote_folio_list() accordingly.

Bug 1 reproduction:
  Assume a system with 4 nodes, where nodes 0-1 are top-tier and
  nodes 2-3 are far-tier memory. All nodes have equal capacity.

  Test script:
    echo 1 &gt; /sys/kernel/mm/numa/demotion_enabled
    mkdir /sys/fs/cgroup/test
    echo +cpuset &gt; /sys/fs/cgroup/cgroup.subtree_control
    echo "0-2" &gt; /sys/fs/cgroup/test/cpuset.mems
    echo $$ &gt; /sys/fs/cgroup/test/cgroup.procs
    swapoff -a
    # Expectation: Should respect node 0-2 limit.
    # Observation: Node 3 shows significant allocation (MemFree drops)
    stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1

Bug 2 reproduction:
  Assume a system with 6 nodes, where nodes 0-2 are top-tier,
  node 3 is a far-tier node, and nodes 4-5 are the farthest-tier nodes.
  All nodes have equal capacity.

  Test script:
    echo 1 &gt; /sys/kernel/mm/numa/demotion_enabled
    mkdir /sys/fs/cgroup/test
    echo +cpuset &gt; /sys/fs/cgroup/cgroup.subtree_control
    echo "0-2,4-5" &gt; /sys/fs/cgroup/test/cpuset.mems
    echo $$ &gt; /sys/fs/cgroup/test/cgroup.procs
    swapoff -a
    # Expectation: Pages are demoted to Nodes 4-5
    # Observation: No pages are demoted before oom.
    stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1,2

Link: https://lkml.kernel.org/r/20260114205305.2869796-1-bingjiao@google.com
Link: https://lkml.kernel.org/r/20260114205305.2869796-2-bingjiao@google.com
Fixes: 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim")
Signed-off-by: Bing Jiao &lt;bingjiao@google.com&gt;
Acked-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Cc: Axel Rasmussen &lt;axelrasmussen@google.com&gt;
Cc: David Hildenbrand &lt;david@kernel.org&gt;
Cc: Gregory Price &lt;gourry@gourry.net&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Joshua Hahn &lt;joshua.hahnjy@gmail.com&gt;
Cc: Liam Howlett &lt;liam.howlett@oracle.com&gt;
Cc: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Qi Zheng &lt;zhengqi.arch@bytedance.com&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Waiman Long &lt;longman@redhat.com&gt;
Cc: Wei Xu &lt;weixugc@google.com&gt;
Cc: Yuanchu Xie &lt;yuanchu@google.com&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Sasha Levin &lt;sashal@kernel.org&gt;
</content>
</entry>
<entry>
<title>memcg: skip cgroup_file_notify if spinning is not allowed</title>
<updated>2025-10-07T21:01:11+00:00</updated>
<author>
<name>Shakeel Butt</name>
<email>shakeel.butt@linux.dev</email>
</author>
<published>2025-09-22T22:02:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=fcc0669c5aa681994c507b50f1c706c969d99730'/>
<id>urn:sha1:fcc0669c5aa681994c507b50f1c706c969d99730</id>
<content type='text'>
Generally memcg charging is allowed from all the contexts including NMI
where even spinning on spinlock can cause locking issues.  However one
call chain was missed during the addition of memcg charging from any
context support.  That is try_charge_memcg() -&gt; memcg_memory_event() -&gt;
cgroup_file_notify().

The possible function call tree under cgroup_file_notify() can acquire
many different spin locks in spinning mode.  Some of them are
cgroup_file_kn_lock, kernfs_notify_lock, pool_workqeue's lock.  So, let's
just skip cgroup_file_notify() from memcg charging if the context does not
allow spinning.

Alternative approach was also explored where instead of skipping
cgroup_file_notify(), we defer the memcg event processing to irq_work [1].
However it adds complexity and it was decided to keep things simple until
we need more memcg events with !allow_spinning requirement.

Link: https://lore.kernel.org/all/5qi2llyzf7gklncflo6gxoozljbm4h3tpnuv4u4ej4ztysvi6f@x44v7nz2wdzd/ [1]
Link: https://lkml.kernel.org/r/20250922220203.261714-1-shakeel.butt@linux.dev
Fixes: 3ac4638a734a ("memcg: make memcg_rstat_updated nmi safe")
Signed-off-by: Shakeel Butt &lt;shakeel.butt@linux.dev&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Closes: https://lore.kernel.org/all/20250905061919.439648-1-yepeilin@google.com/
Cc: Alexei Starovoitov &lt;ast@kernel.org&gt;
Cc: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Kumar Kartikeya Dwivedi &lt;memxor@gmail.com&gt;
Cc: Muchun Song &lt;muchun.song@linux.dev&gt;
Cc: Peilin Ye &lt;yepeilin@google.com&gt;
Cc: Roman Gushchin &lt;roman.gushchin@linux.dev&gt;
Cc: Tejun Heo &lt;tj@kernel.org&gt;
Cc: &lt;stable@vger.kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2025-10-03T01:18:33+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-10-03T01:18:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.landau.one/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8804d970fab45726b3c7cd7f240b31122aa94219'/>
<id>urn:sha1:8804d970fab45726b3c7cd7f240b31122aa94219</id>
<content type='text'>
Pull MM updates from Andrew Morton:

 - "mm, swap: improve cluster scan strategy" from Kairui Song improves
   performance and reduces the failure rate of swap cluster allocation

 - "support large align and nid in Rust allocators" from Vitaly Wool
   permits Rust allocators to set NUMA node and large alignment when
   perforning slub and vmalloc reallocs

 - "mm/damon/vaddr: support stat-purpose DAMOS" from Yueyang Pan extend
   DAMOS_STAT's handling of the DAMON operations sets for virtual
   address spaces for ops-level DAMOS filters

 - "execute PROCMAP_QUERY ioctl under per-vma lock" from Suren
   Baghdasaryan reduces mmap_lock contention during reads of
   /proc/pid/maps

 - "mm/mincore: minor clean up for swap cache checking" from Kairui Song
   performs some cleanup in the swap code

 - "mm: vm_normal_page*() improvements" from David Hildenbrand provides
   code cleanup in the pagemap code

 - "add persistent huge zero folio support" from Pankaj Raghav provides
   a block layer speedup by optionalls making the
   huge_zero_pagepersistent, instead of releasing it when its refcount
   falls to zero

 - "kho: fixes and cleanups" from Mike Rapoport adds a few touchups to
   the recently added Kexec Handover feature

 - "mm: make mm-&gt;flags a bitmap and 64-bit on all arches" from Lorenzo
   Stoakes turns mm_struct.flags into a bitmap. To end the constant
   struggle with space shortage on 32-bit conflicting with 64-bit's
   needs

 - "mm/swapfile.c and swap.h cleanup" from Chris Li cleans up some swap
   code

 - "selftests/mm: Fix false positives and skip unsupported tests" from
   Donet Tom fixes a few things in our selftests code

 - "prctl: extend PR_SET_THP_DISABLE to only provide THPs when advised"
   from David Hildenbrand "allows individual processes to opt-out of
   THP=always into THP=madvise, without affecting other workloads on the
   system".

   It's a long story - the [1/N] changelog spells out the considerations

 - "Add and use memdesc_flags_t" from Matthew Wilcox gets us started on
   the memdesc project. Please see

      https://kernelnewbies.org/MatthewWilcox/Memdescs and
      https://blogs.oracle.com/linux/post/introducing-memdesc

 - "Tiny optimization for large read operations" from Chi Zhiling
   improves the efficiency of the pagecache read path

 - "Better split_huge_page_test result check" from Zi Yan improves our
   folio splitting selftest code

 - "test that rmap behaves as expected" from Wei Yang adds some rmap
   selftests

 - "remove write_cache_pages()" from Christoph Hellwig removes that
   function and converts its two remaining callers

 - "selftests/mm: uffd-stress fixes" from Dev Jain fixes some UFFD
   selftests issues

 - "introduce kernel file mapped folios" from Boris Burkov introduces
   the concept of "kernel file pages". Using these permits btrfs to
   account its metadata pages to the root cgroup, rather than to the
   cgroups of random inappropriate tasks

 - "mm/pageblock: improve readability of some pageblock handling" from
   Wei Yang provides some readability improvements to the page allocator
   code

 - "mm/damon: support ARM32 with LPAE" from SeongJae Park teaches DAMON
   to understand arm32 highmem

 - "tools: testing: Use existing atomic.h for vma/maple tests" from
   Brendan Jackman performs some code cleanups and deduplication under
   tools/testing/

 - "maple_tree: Fix testing for 32bit compiles" from Liam Howlett fixes
   a couple of 32-bit issues in tools/testing/radix-tree.c

 - "kasan: unify kasan_enabled() and remove arch-specific
   implementations" from Sabyrzhan Tasbolatov moves KASAN arch-specific
   initialization code into a common arch-neutral implementation

 - "mm: remove zpool" from Johannes Weiner removes zspool - an
   indirection layer which now only redirects to a single thing
   (zsmalloc)

 - "mm: task_stack: Stack handling cleanups" from Pasha Tatashin makes a
   couple of cleanups in the fork code

 - "mm: remove nth_page()" from David Hildenbrand makes rather a lot of
   adjustments at various nth_page() callsites, eventually permitting
   the removal of that undesirable helper function

 - "introduce kasan.write_only option in hw-tags" from Yeoreum Yun
   creates a KASAN read-only mode for ARM, using that architecture's
   memory tagging feature. It is felt that a read-only mode KASAN is
   suitable for use in production systems rather than debug-only

 - "mm: hugetlb: cleanup hugetlb folio allocation" from Kefeng Wang does
   some tidying in the hugetlb folio allocation code

 - "mm: establish const-correctness for pointer parameters" from Max
   Kellermann makes quite a number of the MM API functions more accurate
   about the constness of their arguments. This was getting in the way
   of subsystems (in this case CEPH) when they attempt to improving
   their own const/non-const accuracy

 - "Cleanup free_pages() misuse" from Vishal Moola fixes a number of
   code sites which were confused over when to use free_pages() vs
   __free_pages()

 - "Add Rust abstraction for Maple Trees" from Alice Ryhl makes the
   mapletree code accessible to Rust. Required by nouveau and by its
   forthcoming successor: the new Rust Nova driver

 - "selftests/mm: split_huge_page_test: split_pte_mapped_thp
   improvements" from David Hildenbrand adds a fix and some cleanups to
   the thp selftesting code

 - "mm, swap: introduce swap table as swap cache (phase I)" from Chris
   Li and Kairui Song is the first step along the path to implementing
   "swap tables" - a new approach to swap allocation and state tracking
   which is expected to yield speed and space improvements. This
   patchset itself yields a 5-20% performance benefit in some situations

 - "Some ptdesc cleanups" from Matthew Wilcox utilizes the new memdesc
   layer to clean up the ptdesc code a little

 - "Fix va_high_addr_switch.sh test failure" from Chunyu Hu fixes some
   issues in our 5-level pagetable selftesting code

 - "Minor fixes for memory allocation profiling" from Suren Baghdasaryan
   addresses a couple of minor issues in relatively new memory
   allocation profiling feature

 - "Small cleanups" from Matthew Wilcox has a few cleanups in
   preparation for more memdesc work

 - "mm/damon: add addr_unit for DAMON_LRU_SORT and DAMON_RECLAIM" from
   Quanmin Yan makes some changes to DAMON in furtherance of supporting
   arm highmem

 - "selftests/mm: Add -Wunreachable-code and fix warnings" from Muhammad
   Anjum adds that compiler check to selftests code and fixes the
   fallout, by removing dead code

 - "Improvements to Victim Process Thawing and OOM Reaper Traversal
   Order" from zhongjinji makes a number of improvements in the OOM
   killer: mainly thawing a more appropriate group of victim threads so
   they can release resources

 - "mm/damon: misc fixups and improvements for 6.18" from SeongJae Park
   is a bunch of small and unrelated fixups for DAMON

 - "mm/damon: define and use DAMON initialization check function" from
   SeongJae Park implement reliability and maintainability improvements
   to a recently-added bug fix

 - "mm/damon/stat: expose auto-tuned intervals and non-idle ages" from
   SeongJae Park provides additional transparency to userspace clients
   of the DAMON_STAT information

 - "Expand scope of khugepaged anonymous collapse" from Dev Jain removes
   some constraints on khubepaged's collapsing of anon VMAs. It also
   increases the success rate of MADV_COLLAPSE against an anon vma

 - "mm: do not assume file == vma-&gt;vm_file in compat_vma_mmap_prepare()"
   from Lorenzo Stoakes moves us further towards removal of
   file_operations.mmap(). This patchset concentrates upon clearing up
   the treatment of stacked filesystems

 - "mm: Improve mlock tracking for large folios" from Kiryl Shutsemau
   provides some fixes and improvements to mlock's tracking of large
   folios. /proc/meminfo's "Mlocked" field became more accurate

 - "mm/ksm: Fix incorrect accounting of KSM counters during fork" from
   Donet Tom fixes several user-visible KSM stats inaccuracies across
   forks and adds selftest code to verify these counters

 - "mm_slot: fix the usage of mm_slot_entry" from Wei Yang addresses
   some potential but presently benign issues in KSM's mm_slot handling

* tag 'mm-stable-2025-10-01-19-00' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (372 commits)
  mm: swap: check for stable address space before operating on the VMA
  mm: convert folio_page() back to a macro
  mm/khugepaged: use start_addr/addr for improved readability
  hugetlbfs: skip VMAs without shareable locks in hugetlb_vmdelete_list
  alloc_tag: fix boot failure due to NULL pointer dereference
  mm: silence data-race in update_hiwater_rss
  mm/memory-failure: don't select MEMORY_ISOLATION
  mm/khugepaged: remove definition of struct khugepaged_mm_slot
  mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL
  hugetlb: increase number of reserving hugepages via cmdline
  selftests/mm: add fork inheritance test for ksm_merging_pages counter
  mm/ksm: fix incorrect KSM counter handling in mm_struct during fork
  drivers/base/node: fix double free in register_one_node()
  mm: remove PMD alignment constraint in execmem_vmalloc()
  mm/memory_hotplug: fix typo 'esecially' -&gt; 'especially'
  mm/rmap: improve mlock tracking for large folios
  mm/filemap: map entire large folio faultaround
  mm/fault: try to map the entire file folio in finish_fault()
  mm/rmap: mlock large folios in try_to_unmap_one()
  mm/rmap: fix a mlock race condition in folio_referenced_one()
  ...
</content>
</entry>
</feed>
