Messages in this thread Patch in this message | | | Subject | Re: Possible mem cgroup bug in kernels between 4.18.0 and 5.3-rc1. | From | Masoud Sharbiani <> | Date | Sat, 03 Aug 2019 10:41:40 -0700 |
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> On Aug 3, 2019, at 8:51 AM, Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> wrote: > > Masoud, will you try this patch?
Gladly. It looks like it is working (and OOMing properly).
> > By the way, is /sys/fs/cgroup/memory/leaker/memory.usage_in_bytes remains non-zero > despite /sys/fs/cgroup/memory/leaker/tasks became empty due to memcg OOM killer expected? > Deleting big-data-file.bin after memcg OOM killer reduces some, but still remains > non-zero.
Yes. I had not noticed that:
[ 1114.190477] oom_reaper: reaped process 1942 (leaker), now anon-rss:0kB, file- rss:0kB, shmem-rss:0kB ./test-script.sh: line 16: 1942 Killed ./leaker -p 10240 -c 100000
[root@localhost laleaker]# cat /sys/fs/cgroup/memory/leaker/memory.usage_in_bytes 3194880 [root@localhost laleaker]# cat /sys/fs/cgroup/memory/leaker/memory.limit_in_bytes 536870912 [root@localhost laleaker]# rm -f big-data-file.bin [root@localhost laleaker]# cat /sys/fs/cgroup/memory/leaker/memory.usage_in_bytes 2838528
Thanks! Masoud
PS: Tried hand-back-porting it to 4.19-y and it didn’t work. I think there are other patches between 4.19.0 and 5.3 that could be necessary…
> > ---------------------------------------- > From 2f92c70f390f42185c6e2abb8dda98b1b7d02fa9 Mon Sep 17 00:00:00 2001 > From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Date: Sun, 4 Aug 2019 00:41:30 +0900 > Subject: [PATCH] memcg, oom: don't require __GFP_FS when invoking memcg OOM killer > > Masoud Sharbiani noticed that commit 29ef680ae7c21110 ("memcg, oom: move > out_of_memory back to the charge path") broke memcg OOM called from > __xfs_filemap_fault() path. It turned out that try_chage() is retrying > forever without making forward progress because mem_cgroup_oom(GFP_NOFS) > cannot invoke the OOM killer due to commit 3da88fb3bacfaa33 ("mm, oom: > move GFP_NOFS check to out_of_memory"). Regarding memcg OOM, we need to > bypass GFP_NOFS check in order to guarantee forward progress. > > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> > Reported-by: Masoud Sharbiani <msharbiani@apple.com> > Bisected-by: Masoud Sharbiani <msharbiani@apple.com> > Fixes: 29ef680ae7c21110 ("memcg, oom: move out_of_memory back to the charge path") > --- > mm/oom_kill.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index eda2e2a..26804ab 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -1068,9 +1068,10 @@ bool out_of_memory(struct oom_control *oc) > * The OOM killer does not compensate for IO-less reclaim. > * pagefault_out_of_memory lost its gfp context so we have to > * make sure exclude 0 mask - all other users should have at least > - * ___GFP_DIRECT_RECLAIM to get here. > + * ___GFP_DIRECT_RECLAIM to get here. But mem_cgroup_oom() has to > + * invoke the OOM killer even if it is a GFP_NOFS allocation. > */ > - if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS)) > + if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS) && !is_memcg_oom(oc)) > return true; > > /* > -- > 1.8.3.1 > >
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