On Wed, Nov 30, 2016 at 07:30:17PM +0100, Michal Hocko wrote:

On Wed 30-11-16 13:16:53, Johannes Weiner wrote:

quoted

Hi Michael,

On Wed, Nov 30, 2016 at 06:00:40PM +0100, Michal Hocko wrote:

[...]

quoted

quoted

diff --git a/mm/workingset.c b/mm/workingset.c
index 617475f529f4..0f07522c5c0e 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c

@@ -348,7 +348,7 @@ static unsigned long count_shadow_nodes(struct shrinker *shrinker,
 	shadow_nodes = list_lru_shrink_count(&workingset_shadow_nodes, sc);
 	local_irq_enable();
 
-	if (memcg_kmem_enabled()) {
+	if (memcg_kmem_enabled() && sc->memcg) {
 		pages = mem_cgroup_node_nr_lru_pages(sc->memcg, sc->nid,
 						     LRU_ALL_FILE);
 	} else {

If we do that, I'd remove the racy memcg_kmem_enabled() check
altogether and just check for whether we have a memcg or not.

But that would make this a memcg aware shrinker even when kmem is not
enabled...

But now that I am looking into the code
shrink_slab:
		if (memcg_kmem_enabled() &&
		    !!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE))
			continue;

this should be taken care of already. So sc->memcg should be indeed
sufficient. So unless I am missing something I will respin my local
patch and post it later after the reporter has some time to test the
current one.

The above patch seems to help. At least the problem haven't occurred for
the last ~40 VM startups.

quoted

What do you think, Vladimir?

-- 
Pozdrawiam / Best Regards,
Marek Marczykowski-Górecki  | RLU #390519
marmarek at staszic waw pl  | xmpp:marmarek at staszic waw pl