[PATCH] mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker
Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken.
It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter.
Add mem_cgroup_disabled() check to make reclaimer work as expected.
Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Reported-by: Shakeel Butt shakeelb@google.com Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Johannes Weiner hannes@cmpxchg.org Cc: Michal Hocko mhocko@suse.com Cc: Kirill Tkhai ktkhai@virtuozzo.com Cc: Roman Gushchin guro@fb.com Cc: Hugh Dickins hughd@google.com Cc: Qian Cai cai@lca.pw Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: stable@vger.kernel.org 4.19+ Signed-off-by: Yang Shi yang.shi@linux.alibaba.com --- mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index f8e3dcd..c10dc02 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -684,7 +684,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, unsigned long ret, freed = 0; struct shrinker *shrinker;
- if (!mem_cgroup_is_root(memcg)) + /* + * The root memcg might be allocated even though memcg is disabled + * via "cgroup_disable=memory" boot parameter. This could make + * mem_cgroup_is_root() return false, then just run memcg slab + * shrink, but skip global shrink. This may result in premature + * oom. + */ + if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority);
if (!down_read_trylock(&shrinker_rwsem))
On Wed, Jul 17, 2019 at 10:45 AM Yang Shi yang.shi@linux.alibaba.com wrote:
Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken.
It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter.
Add mem_cgroup_disabled() check to make reclaimer work as expected.
Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Reported-by: Shakeel Butt shakeelb@google.com Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Johannes Weiner hannes@cmpxchg.org Cc: Michal Hocko mhocko@suse.com Cc: Kirill Tkhai ktkhai@virtuozzo.com Cc: Roman Gushchin guro@fb.com Cc: Hugh Dickins hughd@google.com Cc: Qian Cai cai@lca.pw Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: stable@vger.kernel.org 4.19+ Signed-off-by: Yang Shi yang.shi@linux.alibaba.com
Reviewed-by: Shakeel Butt shakeelb@google.com
mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index f8e3dcd..c10dc02 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -684,7 +684,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, unsigned long ret, freed = 0; struct shrinker *shrinker;
if (!mem_cgroup_is_root(memcg))
/** The root memcg might be allocated even though memcg is disabled* via "cgroup_disable=memory" boot parameter. This could make* mem_cgroup_is_root() return false, then just run memcg slab* shrink, but skip global shrink. This may result in premature* oom.*/if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority); if (!down_read_trylock(&shrinker_rwsem))-- 1.8.3.1
On 17.07.2019 20:45, Yang Shi wrote:
Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken.
It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter.
Add mem_cgroup_disabled() check to make reclaimer work as expected.
Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Reported-by: Shakeel Butt shakeelb@google.com Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Johannes Weiner hannes@cmpxchg.org Cc: Michal Hocko mhocko@suse.com Cc: Kirill Tkhai ktkhai@virtuozzo.com Cc: Roman Gushchin guro@fb.com Cc: Hugh Dickins hughd@google.com Cc: Qian Cai cai@lca.pw Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: stable@vger.kernel.org 4.19+ Signed-off-by: Yang Shi yang.shi@linux.alibaba.com
Reviewed-by: Kirill Tkhai ktkhai@virtuozzo.com
Surprise really.
We have mem_cgroup as not early inited, so all of these boundary cases and checks has to be supported. But it looks like it's not possible to avoid that in any way.
mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index f8e3dcd..c10dc02 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -684,7 +684,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, unsigned long ret, freed = 0; struct shrinker *shrinker;
- if (!mem_cgroup_is_root(memcg))
- /*
* The root memcg might be allocated even though memcg is disabled* via "cgroup_disable=memory" boot parameter. This could make* mem_cgroup_is_root() return false, then just run memcg slab* shrink, but skip global shrink. This may result in premature* oom.*/- if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority);
if (!down_read_trylock(&shrinker_rwsem))
On Thu 18-07-19 01:45:26, Yang Shi wrote:
Shakeel Butt reported premature oom on kernel with "cgroup_disable=memory" since mem_cgroup_is_root() returns false even though memcg is actually NULL. The drop_caches is also broken.
It is because commit aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") removed the !memcg check before !mem_cgroup_is_root(). And, surprisingly root memcg is allocated even though memory cgroup is disabled by kernel boot parameter.
Add mem_cgroup_disabled() check to make reclaimer work as expected.
Fixes: aeed1d325d42 ("mm/vmscan.c: generalize shrink_slab() calls in shrink_node()") Reported-by: Shakeel Butt shakeelb@google.com Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Johannes Weiner hannes@cmpxchg.org Cc: Michal Hocko mhocko@suse.com Cc: Kirill Tkhai ktkhai@virtuozzo.com Cc: Roman Gushchin guro@fb.com Cc: Hugh Dickins hughd@google.com Cc: Qian Cai cai@lca.pw Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: stable@vger.kernel.org 4.19+ Signed-off-by: Yang Shi yang.shi@linux.alibaba.com
Acked-by: Michal Hocko mhocko@suse.com
mm/vmscan.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c index f8e3dcd..c10dc02 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -684,7 +684,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid, unsigned long ret, freed = 0; struct shrinker *shrinker;
- if (!mem_cgroup_is_root(memcg))
- /*
* The root memcg might be allocated even though memcg is disabled* via "cgroup_disable=memory" boot parameter. This could make* mem_cgroup_is_root() return false, then just run memcg slab* shrink, but skip global shrink. This may result in premature* oom.*/- if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg)) return shrink_slab_memcg(gfp_mask, nid, memcg, priority);
if (!down_read_trylock(&shrinker_rwsem)) -- 1.8.3.1
linux-stable-mirror@lists.linaro.org
-
Kirill Tkhai -
Michal Hocko -
Shakeel Butt -
Yang Shi