Re: mm: mkfs.ext4 invoked oom-killer on i386 - pagecache_get_page

[Naresh Kamboju]

On Thu, 21 May 2020 at 00:39, Chris Down <chris@xxxxxxxxxxxxxx> wrote:
>
> Hi Naresh,
>
> Naresh Kamboju writes:
> >As a part of investigation on this issue LKFT teammate Anders Roxell
> >git bisected the problem and found bad commit(s) which caused this problem.
> >
> >The following two patches have been reverted on next-20200519 and retested the
> >reproducible steps and confirmed the test case mkfs -t ext4 got PASS.
> >( invoked oom-killer is gone now)
> >
> >Revert "mm, memcg: avoid stale protection values when cgroup is above
> >protection"
> >    This reverts commit 23a53e1c02006120f89383270d46cbd040a70bc6.
> >
> >Revert "mm, memcg: decouple e{low,min} state mutations from protection
> >checks"
> >    This reverts commit 7b88906ab7399b58bb088c28befe50bcce076d82.
>
> Thanks Anders and Naresh for tracking this down and reverting.
>
> I'll take a look tomorrow. I don't see anything immediately obviously wrong in
> either of those commits from a (very) cursory glance, but they should only be
> taking effect if protections are set.
>
> Since you have i386 hardware available, and I don't, could you please apply
> only "avoid stale protection" again and check if it only happens with that
> commit, or requires both? That would help narrow down the suspects.

Not both.
The bad commit is
"mm, memcg: decouple e{low,min} state mutations from protection checks"

>
> Do you use any memcg protections in these tests?
I see three MEMCG configs and please find the kernel config link
for more details.

CONFIG_MEMCG=y
CONFIG_MEMCG_SWAP=y
CONFIG_MEMCG_KMEM=y

kernel config link,
https://builds.tuxbuild.com/8lg6WQibcwtQRRtIa0bcFA/kernel.config

- Naresh