[Devel] [PATCH rh7 6/6] mm: oom_kill: clean up victim marking and exiting interfaces

[Vladimir Davydov]

From: Johannes Weiner <hannes at cmpxchg.org>

Rename unmark_oom_victim() to exit_oom_victim().  Marking and unmarking
are related in functionality, but the interface is not symmetrical at
all: one is an internal OOM killer function used during the killing, the
other is for an OOM victim to signal its own death on exit later on.
This has locking implications, see follow-up changes.

While at it, rename mark_tsk_oom_victim() to mark_oom_victim(), which
is easier on the eye.

Signed-off-by: Johannes Weiner <hannes at cmpxchg.org>
Acked-by: David Rientjes <rientjes at google.com>
Acked-by: Michal Hocko <mhocko at suse.cz>
Cc: Tetsuo Handa <penguin-kernel at I-love.SAKURA.ne.jp>
Cc: Andrea Arcangeli <aarcange at redhat.com>
Cc: Dave Chinner <david at fromorbit.com>
Cc: Vlastimil Babka <vbabka at suse.cz>
Signed-off-by: Andrew Morton <akpm at linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
(cherry picked from commit 16e951966f05da5ccd650104176f6ba289f7fa20)
Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>

Conflicts:
	include/linux/oom.h
	mm/memcontrol.c
	mm/oom_kill.c
---
 drivers/staging/android/lowmemorykiller.c |  2 +-
 include/linux/oom.h                       |  7 ++++---
 kernel/exit.c                             |  2 +-
 mm/memcontrol.c                           |  2 +-
 mm/oom_kill.c                             | 14 +++++++-------
 5 files changed, 14 insertions(+), 13 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
index 4dd6a344a799..433e9a7cb391 100644
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -164,7 +164,7 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
 		 * infrastructure. There is no real reason why the selected
 		 * task should have access to the memory reserves.
 		 */
-		mark_tsk_oom_victim(selected);
+		mark_oom_victim(selected);
 		send_sig(SIGKILL, selected, 0);
 		rem += selected_tasksize;
 	}
diff --git a/include/linux/oom.h b/include/linux/oom.h
index 3c37f1e2b98a..486fc6f3cdc1 100644
--- a/include/linux/oom.h
+++ b/include/linux/oom.h
@@ -52,9 +52,7 @@ static inline bool oom_task_origin(const struct task_struct *p)
 /* linux/mm/oom_group.c */
 extern int get_task_oom_score_adj(struct task_struct *t);
 
-extern void mark_tsk_oom_victim(struct task_struct *tsk);
-
-extern void unmark_oom_victim(void);
+extern void mark_oom_victim(struct task_struct *tsk);
 
 extern unsigned long oom_badness(struct task_struct *p, struct mem_cgroup *memcg,
 			  const nodemask_t *nodemask, unsigned long totalpages);
@@ -75,6 +73,9 @@ extern enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
 
 extern void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 		int order, nodemask_t *mask, bool force_kill);
+
+extern void exit_oom_victim(void);
+
 extern int register_oom_notifier(struct notifier_block *nb);
 extern int unregister_oom_notifier(struct notifier_block *nb);
 
diff --git a/kernel/exit.c b/kernel/exit.c
index 1b13207f651e..1cc765b48bd7 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -521,7 +521,7 @@ static void exit_mm(struct task_struct * tsk)
 	mm_update_next_owner(mm);
 	mmput(mm);
 	if (test_thread_flag(TIF_MEMDIE))
-		unmark_oom_victim();
+		exit_oom_victim();
 }
 
 /*
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 032b17c0b7ab..9f2d1d518df4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1964,7 +1964,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	 * quickly exit and free its memory.
 	 */
 	if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
-		mark_tsk_oom_victim(current);
+		mark_oom_victim(current);
 		return;
 	}
 
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 7b106e878069..7dfbcb6ffb80 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -409,10 +409,10 @@ static void dump_header(struct task_struct *p, gfp_t gfp_mask, int order,
 }
 
 /**
- * mark_tsk_oom_victim - marks the given taks as OOM victim.
+ * mark_oom_victim - mark the given task as OOM victim
  * @tsk: task to mark
  */
-void mark_tsk_oom_victim(struct task_struct *tsk)
+void mark_oom_victim(struct task_struct *tsk)
 {
 	set_tsk_thread_flag(tsk, TIF_MEMDIE);
 
@@ -426,9 +426,9 @@ void mark_tsk_oom_victim(struct task_struct *tsk)
 }
 
 /**
- * unmark_oom_victim - unmarks the current task as OOM victim.
+ * exit_oom_victim - note the exit of an OOM victim
  */
-void unmark_oom_victim(void)
+void exit_oom_victim(void)
 {
 	clear_thread_flag(TIF_MEMDIE);
 }
@@ -457,7 +457,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
 	 */
 	task_lock(p);
 	if (p->mm && p->flags & PF_EXITING) {
-		mark_tsk_oom_victim(p);
+		mark_oom_victim(p);
 		task_unlock(p);
 		put_task_struct(p);
 		return;
@@ -512,7 +512,7 @@ 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;
-	mark_tsk_oom_victim(victim);
+	mark_oom_victim(victim);
 	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)),
@@ -675,7 +675,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask,
 	 */
 	if (current->mm &&
 	    (fatal_signal_pending(current) || current->flags & PF_EXITING)) {
-		mark_tsk_oom_victim(current);
+		mark_oom_victim(current);
 		return;
 	}
 
-- 
2.1.4