[Devel] [PATCH rh7] memcg: count all oom kills

[Vladimir Davydov]

We do not count processes killed because they share victim's mm. Fix it.

Fixes: 66053f4201e41 ("memcg: count oom kills")
Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
 include/linux/memcontrol.h |  4 ++--
 mm/memcontrol.c            | 15 +++++++++++++--
 mm/oom_kill.c              |  3 ++-
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index eb7ae43a57f9..ac3f16f0ee28 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -122,7 +122,7 @@ unsigned long mem_cgroup_get_lru_size(struct lruvec *lruvec, enum lru_list);
 void mem_cgroup_update_lru_size(struct lruvec *, enum lru_list, int);
 extern bool mem_cgroup_below_oom_guarantee(struct task_struct *p);
 extern void mem_cgroup_note_oom_kill(struct mem_cgroup *memcg,
-				     struct mm_struct *mm);
+				     struct task_struct *task);
 extern void mem_cgroup_print_oom_info(struct mem_cgroup *memcg,
 					struct task_struct *p);
 extern void mem_cgroup_replace_page_cache(struct page *oldpage,
@@ -351,7 +351,7 @@ static inline bool mem_cgroup_below_oom_guarantee(struct task_struct *p)
 }
 
 static inline void
-mem_cgroup_note_oom_kill(struct mem_cgroup *memcg, struct mm_struct *mm)
+mem_cgroup_note_oom_kill(struct mem_cgroup *memcg, struct task_struct *task)
 {
 }
 
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 52c787165b17..0cb329028a29 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1623,14 +1623,25 @@ bool mem_cgroup_below_oom_guarantee(struct task_struct *p)
 }
 
 void mem_cgroup_note_oom_kill(struct mem_cgroup *root_memcg,
-			      struct mm_struct *mm)
+			      struct task_struct *task)
 {
 	struct mem_cgroup *memcg, *memcg_to_put;
+	struct task_struct *p;
 
 	if (!root_memcg)
 		root_memcg = root_mem_cgroup;
 
-	memcg_to_put = memcg = try_get_mem_cgroup_from_mm(mm);
+	p = find_lock_task_mm(task);
+	if (p) {
+		memcg = try_get_mem_cgroup_from_mm(p->mm);
+		task_unlock(p);
+	} else {
+		rcu_read_lock();
+		memcg = mem_cgroup_from_task(task);
+		css_get(&memcg->css);
+		rcu_read_unlock();
+	}
+	memcg_to_put = memcg;
 	if (!memcg || !mem_cgroup_same_or_subtree(root_memcg, memcg))
 		memcg = root_memcg;
 
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index c99a5f559286..70893730524a 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -498,7 +498,6 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 
 	/* mm cannot safely be dereferenced after task_unlock(victim) */
 	mm = victim->mm;
-	mem_cgroup_note_oom_kill(memcg, mm);
 	pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB\n",
 		task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
 		K(get_mm_counter(victim->mm, MM_ANONPAGES)),
@@ -526,11 +525,13 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 				task_pid_nr(p), p->comm);
 			task_unlock(p);
 			do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, true);
+			mem_cgroup_note_oom_kill(memcg, p);
 		}
 	rcu_read_unlock();
 
 	set_tsk_thread_flag(victim, TIF_MEMDIE);
 	do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, true);
+	mem_cgroup_note_oom_kill(memcg, victim);
 	put_task_struct(victim);
 }
 #undef K
-- 
2.1.4