Messages in this thread | | | From | Shakeel Butt <> | Date | Mon, 26 Apr 2021 12:39:44 -0700 | Subject | Re: [PATCH v2 1/1] memcg: enable accounting for pids in nested pid namespaces |
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On Sat, Apr 24, 2021 at 4:54 AM Vasily Averin <vvs@virtuozzo.com> wrote: > > Commit 5d097056c9a0 ("kmemcg: account certain kmem allocations to memcg") > enabled memcg accounting for pids allocated from init_pid_ns.pid_cachep, > but forgot to adjust the setting for nested pid namespaces. > As a result, pid memory is not accounted exactly where it is really needed, > inside memcg-limited containers with their own pid namespaces. > > Pid was one the first kernel objects enabled for memcg accounting. > init_pid_ns.pid_cachep marked by SLAB_ACCOUNT and we can expect that > any new pids in the system are memcg-accounted. > > Though recently I've noticed that it is wrong. nested pid namespaces creates > own slab caches for pid objects, nested pids have increased size because contain > id both for all parent and for own pid namespaces. The problem is that these slab > caches are _NOT_ marked by SLAB_ACCOUNT, as a result any pids allocated in > nested pid namespaces are not memcg-accounted. > > Pid struct in nested pid namespace consumes up to 500 bytes memory, > 100000 such objects gives us up to ~50Mb unaccounted memory, > this allow container to exceed assigned memcg limits. > > Fixes: 5d097056c9a0 ("kmemcg: account certain kmem allocations to memcg") > Cc: stable@vger.kernel.org > Signed-off-by: Vasily Averin <vvs@virtuozzo.com> > Reviewed-by: Michal Koutný <mkoutny@suse.com> > Acked-by: Christian Brauner <christian.brauner@ubuntu.com> > Acked-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
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