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mm: memcg-v1: fix memsw and TCP failcnt accounting

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Commit 0e2759afca ("page_counter: track failcnt only for legacy
cgroups") made failcnt accounting conditional on track_failcnt.  It
enabled the flag for memcg->memory, but not for memcg->memsw or
memcg->tcpmem.

Consequently, memory.memsw.failcnt remains zero when the memory+swap limit
is hit.  memory.kmem.tcp.limit_in_bytes still sets memcg->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" > "$CG/memory.limit_in_bytes"
    echo "$LIMIT" > "$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" > "$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: 0e2759afca ("page_counter: track failcnt only for legacy cgroups")
Signed-off-by: Guopeng Zhang <zhangguopeng@kylinos.cn>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Tao Cui <cuitao@kylinos.cn>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Guopeng Zhang 2026-08-11 11:08:43 +08:00 • committed by Andrew Morton
commit 92192e9c5e
1 changed files with 2 additions and 0 deletions
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