Re: [PATCH] mm: memcg-v1: fix memory.memsw.failcnt accounting

[Guopeng Zhang <guopeng.zhang@linux.dev>]

在 2026/8/11 02:47, Andrew Morton 写道:
> On Mon, 10 Aug 2026 15:42:47 +0800 Guopeng Zhang <guopeng.zhang@linux.dev> wrote:
> 
>> Commit 0e2759afcaf9 ("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.
>>
>> Consequently, memory.memsw.failcnt remains zero when the memory+swap
>> limit is hit. Enable failcnt accounting for the v1 memsw counter.
>>
>> Reproducer:
>>
>>     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.
> 
> Thanks.  Nice changelog.
> 
>> Fixes: 0e2759afcaf9 ("page_counter: track failcnt only for legacy cgroups")
> 
> I'll add cc:stable to this.
> 
> AI review thinks that memcg->tcpmem.track_failcnt should receive the
> same treatment:
> 
> 	https://sashiko.dev/#/patchset/20260810074247.52747-1-guopeng.zhang@linux.dev

Yeah, tcpmem has the same issue.

I'll add

    memcg->tcpmem.track_failcnt = !memcg_on_dfl;

and update the changelog accordingly in v2.

Thanks,
Guopeng