Re: [PATCH 5/5] memcg: make memcg_rstat_updated nmi safe

[Shakeel Butt <shakeel.butt@linux.dev>]

On Fri, May 16, 2025 at 11:45:39AM +0200, Vlastimil Babka wrote:
> On 5/16/25 08:49, Shakeel Butt wrote:
> > memcg: convert stats_updates to atomic_t
> 
> You have two subjects, I guess delete the second one?

Oops I squashed the patch at the very end and forgot to fix this.

> 
> > Currently kernel maintains memory related stats updates per-cgroup to
> > optimize stats flushing. The stats_updates is defined as atomic64_t
> > which is not nmi-safe on some archs. Actually we don't really need 64bit
> > atomic as the max value stats_updates can get should be less than
> > nr_cpus * MEMCG_CHARGE_BATCH. A normal atomic_t should suffice.
> > 
> > Also the function cgroup_rstat_updated() is still not nmi-safe but there
> > is parallel effort to make it nmi-safe, so until then let's ignore it in
> > the nmi context.
> > 
> > Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
> 
> Acked-by: Vlastimil Babka <vbabka@suse.cz>

Thanks a lot.