Re: [PATCH 0/2] memcg: mm_update_next_owner() should skip kthreads

[Oleg Nesterov]

On 04/18, Michal Hocko wrote:
>
> On Fri 18-04-14 19:26:31, Oleg Nesterov wrote:
> > On 04/18, Oleg Nesterov wrote:
> > >
> > > Hmm. I seem to see a bug in this function, it can be fulled by use_mm,
> > > but I am not sure this can explain the problem. I'll send a patch.
> >
> > Untested, please review. But it really looks "obviously wrong", and note
> > that unuse_mm() doesn't do mm_update_next_owner(). (just in case, do not
> > confuse it with unuse_mm() in mm/swapfile.c).
>
> Both patches seem to be correct but I am missinng why they are marked as
> memcg: when they are touching generic mm_update_next_owner path.

Well, this is because I didn't know which prefix should I use. I looked
at git-blame to see who changed this function, picked the random 733eda7ac
"memcg: clear mm->owner when last possible owner leaves" commit and copied
"memcg" from there.

OTOH, mm->owner is used by mm/memcontrol.c, so perhaps the prefix is fine?

I do not even understand why do we have CONFIG_MM_OWNER, perhaps it should
die?

> Anyway, feel free to add
> Reviewed-by: Michal Hocko <mhocko@xxxxxxx>

Thanks!

Oleg.

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