| Message ID | 1563385526-20805-1-git-send-email-yang.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm: vmscan: check if mem cgroup is disabled or not before calling memcg slab shrinker | expand |
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
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))
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(-)