Re: [PATCH] memcg: enable accounting for pids in nested pid namespaces

[Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>]

On Fri, Apr 23, 2021 at 05:09:01AM +0300, Vasily Averin wrote:
> On 4/23/21 4:00 AM, Roman Gushchin wrote:
> > On Thu, Apr 22, 2021 at 08:44:15AM +0300, Vasily Averin wrote:
> >> init_pid_ns.pid_cachep have enabled memcg accounting, though this
> >> setting was disabled for nested pid namespaces.
> >>
> >> Signed-off-by: Vasily Averin <vvs-5HdwGun5lf+gSpxsJD1C4w@public.gmane.org>
> >> ---
> >>  kernel/pid_namespace.c | 3 ++-
> >>  1 file changed, 2 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> >> index 6cd6715..a46a372 100644
> >> --- a/kernel/pid_namespace.c
> >> +++ b/kernel/pid_namespace.c
> >> @@ -51,7 +51,8 @@ static struct kmem_cache *create_pid_cachep(unsigned int level)
> >>  	mutex_lock(&pid_caches_mutex);
> >>  	/* Name collision forces to do allocation under mutex. */
> >>  	if (!*pkc)
> >> -		*pkc = kmem_cache_create(name, len, 0, SLAB_HWCACHE_ALIGN, 0);
> >> +		*pkc = kmem_cache_create(name, len, 0,
> >> +					 SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT, 0);
> >>  	mutex_unlock(&pid_caches_mutex);
> >>  	/* current can fail, but someone else can succeed. */
> >>  	return READ_ONCE(*pkc);
> >> -- 
> >> 1.8.3.1
> >>
> > 
> > It looks good to me! It makes total sense to apply the same rules to the root
> > and non-root levels.
> > 
> > Acked-by: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>
> > 
> > Btw, is there any reason why this patch is not included into the series?
> 
> It is a bugfix and I think it should be added to upstream ASAP.

Then it would be really useful to add some details on why it's a bug,
what kind of problems it causes, etc. If it has to be backported to
stable, please, add cc stable/fixes tag.

Thanks!