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From: Andrew Morton <akpm@linux-foundation.org>
To: akpm@linux-foundation.org, guro@fb.com, hannes@cmpxchg.org,
	ktkhai@virtuozzo.com, linux-mm@kvack.org, mhocko@suse.com,
	mm-commits@vger.kernel.org, shakeelb@google.com,
	stable@vger.kernel.org, torvalds@linux-foundation.org,
	yang.shi@linux.alibaba.com
Subject: [patch 5/6] mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG
Date: Tue, 17 Dec 2019 20:51:52 -0800	[thread overview]
Message-ID: <20191218045152.iNg-dg4P2%akpm@linux-foundation.org> (raw)
In-Reply-To: <20191217205020.6e2eaefc78710ec646e99aa9@linux-foundation.org>

From: Yang Shi <yang.shi@linux.alibaba.com>
Subject: mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG

Since commit 0a432dcbeb32edc ("mm: shrinker: make shrinker not depend on
memcg kmem"), shrinkers' idr is protected by CONFIG_MEMCG instead of
CONFIG_MEMCG_KMEM, so it makes no sense to protect shrinker idr replace
with CONFIG_MEMCG_KMEM.

And in the CONFIG_MEMCG && CONFIG_SLOB case, shrinker_idr contains only
shrinker, and it is deferred_split_shrinker.  But it is never actually
called, since idr_replace() is never compiled due to the wrong #ifdef. 
The deferred_split_shrinker all the time is staying in half-registered
state, and it's never called for subordinate mem cgroups.

Link: http://lkml.kernel.org/r/1575486978-45249-1-git-send-email-yang.shi@linux.alibaba.com
Fixes: 0a432dcbeb32 ("mm: shrinker: make shrinker not depend on memcg kmem")
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: <stable@vger.kernel.org>	[5.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/vmscan.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/vmscan.c~mm-vmscan-protect-shrinker-idr-replace-with-config_memcg
+++ a/mm/vmscan.c
@@ -387,7 +387,7 @@ void register_shrinker_prepared(struct s
 {
 	down_write(&shrinker_rwsem);
 	list_add_tail(&shrinker->list, &shrinker_list);
-#ifdef CONFIG_MEMCG_KMEM
+#ifdef CONFIG_MEMCG
 	if (shrinker->flags & SHRINKER_MEMCG_AWARE)
 		idr_replace(&shrinker_idr, shrinker, shrinker->id);
 #endif
_

  parent reply	other threads:[~2019-12-18  4:51 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-18  4:50 incoming Andrew Morton
2019-12-18  4:51 ` [patch 1/6] kasan: fix crashes on access to memory mapped by vm_map_ram() Andrew Morton
2019-12-18  4:51 ` [patch 2/6] mm/memory.c: add apply_to_existing_page_range() helper Andrew Morton
2019-12-18  4:51 ` [patch 3/6] kasan: use apply_to_existing_page_range() for releasing vmalloc shadow Andrew Morton
2019-12-18  4:51 ` [patch 4/6] kasan: don't assume percpu shadow allocations will succeed Andrew Morton
2019-12-18  4:51 ` Andrew Morton [this message]
2019-12-18  4:51 ` [patch 6/6] lib/Kconfig.debug: fix some messed up configurations Andrew Morton

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