Re: [PATCH] mm: memcg: Don't periodically flush stats when memcg is disabled

[T.J. Mercier]

On Fri, Jan 26, 2024 at 1:06 PM Johannes Weiner <hannes@xxxxxxxxxxx> wrote:
>
> On Fri, Jan 26, 2024 at 08:33:52PM +0000, T.J. Mercier wrote:
> > The root memcg is onlined even when memcg is disabled. When it's onlined
> > a 2 second periodic stat flush is started, but no stat flushing is
> > required when memcg is disabled because there can be no child memcgs.
> > Most calls to flush memcg stats are avoided when memcg is disabled as a
> > result of the mem_cgroup_disabled check [1] added in [2], but the
> > periodic flushing started in mem_cgroup_css_online is not. Skip it.
> >
> > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/memcontrol.c?h=v6.8-rc1#n753
> > [2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7d7ef0a4686abe43cd76a141b340a348f45ecdf2
> >
> > Fixes: aa48e47e3906 ("memcg: infrastructure to flush memcg stats")
> > Reported-by: Minchan Kim <minchan@xxxxxxxxxx>
> > Signed-off-by: T.J. Mercier <tjmercier@xxxxxxxxxx>
>
> With what Shakeel pointed out resolved:
>
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Thanks Shakeel and Johannes. v2 is here, hopefully fixed up correctly:
https://lore.kernel.org/all/20240126211927.1171338-1-tjmercier@xxxxxxxxxx/