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

[Naresh Kamboju]

On Thu, 28 May 2020 at 20:33, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> On Fri 22-05-20 02:23:09, Naresh Kamboju wrote:
> > My apology !
> > As per the test results history this problem started happening from
> > Bad : next-20200430 (still reproducible on next-20200519)
> > Good : next-20200429
> >
> > The git tree / tag used for testing is from linux next-20200430 tag and reverted
> > following three patches and oom-killer problem fixed.
> >
> > Revert "mm, memcg: avoid stale protection values when cgroup is above
> > protection"
> > Revert "mm, memcg: decouple e{low,min} state mutations from protectinn checks"
> > Revert "mm-memcg-decouple-elowmin-state-mutations-from-protection-checks-fix"
>
> The discussion has fragmented and I got lost TBH.
> In http://lkml.kernel.org/r/CA+G9fYuDWGZx50UpD+WcsDeHX9vi3hpksvBAWbMgRZadb0Pkww@xxxxxxxxxxxxxx
> you have said that none of the added tracing output has triggered. Does
> this still hold? Because I still have a hard time to understand how
> those three patches could have the observed effects.

On the other email thread [1] this issue is concluded.

Yafang wrote on May 22 2020,

Regarding the root cause, my guess is it makes a similar mistake that
I tried to fix in the previous patch that the direct reclaimer read a
stale protection value.  But I don't think it is worth to add another
fix. The best way is to revert this commit.


[1]  [PATCH v3 2/2] mm, memcg: Decouple e{low,min} state mutations
from protection checks
https://lore.kernel.org/linux-mm/CALOAHbArZ3NsuR3mCnx_kbSF8ktpjhUF2kaaTa7Mb7ocJajsQg@xxxxxxxxxxxxxx/

- Naresh

> --
> Michal Hocko
> SUSE Labs