| Message ID | 20211108211959.1750915-4-almasrymina@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v1,1/5] mm/shmem: support deterministic charging of tmpfs | expand |
On Mon, Nov 08, 2021 at 01:19:57PM -0800, Mina Almasry wrote: > On remote ooms (OOMs due to remote charging), the oom-killer will attempt > to find a task to kill in the memcg under oom, if the oom-killer > is unable to find one, the oom-killer should simply return ENOMEM to the > allocating process. > > If we're in pagefault path and we're unable to return ENOMEM to the > allocating process, we instead kill the allocating process. > > Signed-off-by: Mina Almasry <almasrymina@google.com> > > Cc: Michal Hocko <mhocko@suse.com> > Cc: Theodore Ts'o <tytso@mit.edu> > Cc: Greg Thelen <gthelen@google.com> > Cc: Shakeel Butt <shakeelb@google.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Hugh Dickins <hughd@google.com> > Cc: Roman Gushchin <songmuchun@bytedance.com> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Hugh Dickins <hughd@google.com> > Cc: Tejun Heo <tj@kernel.org> > Cc: Vladimir Davydov <vdavydov.dev@gmail.com> > Cc: Muchun Song <songmuchun@bytedance.com> > Cc: riel@surriel.com > Cc: linux-mm@kvack.org > Cc: linux-fsdevel@vger.kernel.org > Cc: cgroups@vger.kernel.org > > --- > mm/memcontrol.c | 21 +++++++++++++++++++++ > mm/oom_kill.c | 21 +++++++++++++++++++++ > 2 files changed, 42 insertions(+) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 2e4c20d09f959..fc9c6280266b6 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2664,6 +2664,27 @@ int mem_cgroup_get_name_from_sb(struct super_block *sb, char *buf, size_t len) > return ret < 0 ? ret : 0; > } > > +/* > + * Returns true if current's mm is a descendant of the memcg_under_oom (or > + * equal to it). False otherwise. This is used by the oom-killer to detect > + * ooms due to remote charging. > + */ > +bool is_remote_oom(struct mem_cgroup *memcg_under_oom) > +{ > + struct mem_cgroup *current_memcg; > + bool is_remote_oom; > + > + if (!memcg_under_oom) > + return false; > + > + current_memcg = get_mem_cgroup_from_mm(current->mm); > + is_remote_oom = > + !mem_cgroup_is_descendant(current_memcg, memcg_under_oom); > + css_put(¤t_memcg->css); > + > + return is_remote_oom; You'll be probably better with mem_cgroup_from_task(current) within an rcu read section? > +} > + > /* > * Set or clear (if @memcg is NULL) charge association from file system to > * memcg. If @memcg != NULL, then a css reference must be held by the caller to > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 0a7e16b16b8c3..556329dee273f 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -1106,6 +1106,27 @@ bool out_of_memory(struct oom_control *oc) > } > > select_bad_process(oc); > + > + /* > + * For remote ooms in userfaults, we have no choice but to kill the > + * allocating process. > + */ > + if (!oc->chosen && is_remote_oom(oc->memcg) && current->in_user_fault && > + !oom_unkillable_task(current)) { > + get_task_struct(current); > + oc->chosen = current; > + oom_kill_process( > + oc, "Out of memory (Killing remote allocating task)"); > + return true; > + } > + > + /* > + * For remote ooms in non-userfaults, simply return ENOMEM to the > + * caller. > + */ > + if (!oc->chosen && is_remote_oom(oc->memcg)) > + return false; > + > /* Found nothing?!?! */ > if (!oc->chosen) { I'd move both if's here: if (is_remote_oom(oc->memcg)) { if (current->in_user_fault && !oom_unkillable_task(current)) { ... } return false; } > dump_header(oc, NULL); > -- > 2.34.0.rc0.344.g81b53c2807-goog
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 2e4c20d09f959..fc9c6280266b6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2664,6 +2664,27 @@ int mem_cgroup_get_name_from_sb(struct super_block *sb, char *buf, size_t len) return ret < 0 ? ret : 0; } +/* + * Returns true if current's mm is a descendant of the memcg_under_oom (or + * equal to it). False otherwise. This is used by the oom-killer to detect + * ooms due to remote charging. + */ +bool is_remote_oom(struct mem_cgroup *memcg_under_oom) +{ + struct mem_cgroup *current_memcg; + bool is_remote_oom; + + if (!memcg_under_oom) + return false; + + current_memcg = get_mem_cgroup_from_mm(current->mm); + is_remote_oom = + !mem_cgroup_is_descendant(current_memcg, memcg_under_oom); + css_put(¤t_memcg->css); + + return is_remote_oom; +} + /* * Set or clear (if @memcg is NULL) charge association from file system to * memcg. If @memcg != NULL, then a css reference must be held by the caller to diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 0a7e16b16b8c3..556329dee273f 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -1106,6 +1106,27 @@ bool out_of_memory(struct oom_control *oc) } select_bad_process(oc); + + /* + * For remote ooms in userfaults, we have no choice but to kill the + * allocating process. + */ + if (!oc->chosen && is_remote_oom(oc->memcg) && current->in_user_fault && + !oom_unkillable_task(current)) { + get_task_struct(current); + oc->chosen = current; + oom_kill_process( + oc, "Out of memory (Killing remote allocating task)"); + return true; + } + + /* + * For remote ooms in non-userfaults, simply return ENOMEM to the + * caller. + */ + if (!oc->chosen && is_remote_oom(oc->memcg)) + return false; + /* Found nothing?!?! */ if (!oc->chosen) { dump_header(oc, NULL);
On remote ooms (OOMs due to remote charging), the oom-killer will attempt to find a task to kill in the memcg under oom, if the oom-killer is unable to find one, the oom-killer should simply return ENOMEM to the allocating process. If we're in pagefault path and we're unable to return ENOMEM to the allocating process, we instead kill the allocating process. Signed-off-by: Mina Almasry <almasrymina@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Theodore Ts'o <tytso@mit.edu> Cc: Greg Thelen <gthelen@google.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Roman Gushchin <songmuchun@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Muchun Song <songmuchun@bytedance.com> Cc: riel@surriel.com Cc: linux-mm@kvack.org Cc: linux-fsdevel@vger.kernel.org Cc: cgroups@vger.kernel.org --- mm/memcontrol.c | 21 +++++++++++++++++++++ mm/oom_kill.c | 21 +++++++++++++++++++++ 2 files changed, 42 insertions(+) -- 2.34.0.rc0.344.g81b53c2807-goog