mm,oom: Don't call schedule_timeout_killable() with oom_lock held.

When I was examining a bug which occurs under CPU + memory pressure, I observed that a thread which called out_of_memory() can sleep for minutes at schedule_timeout_killable(1) with oom_lock held when many threads are doing direct reclaim. -------------------- [ 163.357628] b.out invoked oom-killer: gfp_mask=0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null), order=0, oom_score_adj=0 [ 163.360946] CPU: 0 PID: 554 Comm: b.out Not tainted 4.15.0-rc8+ torvalds#216 (...snipped...) [ 163.470193] Out of memory: Kill process 548 (b.out) score 6 or sacrifice child [ 163.471813] Killed process 1191 (b.out) total-vm:2108kB, anon-rss:60kB, file-rss:4kB, shmem-rss:0kB (...snipped...) [ 248.016033] sysrq: SysRq : Show State (...snipped...) [ 249.625720] b.out R running task 0 554 538 0x00000004 [ 249.627778] Call Trace: [ 249.628513] __schedule+0x142/0x4b2 [ 249.629394] schedule+0x27/0x70 [ 249.630114] schedule_timeout+0xd1/0x160 [ 249.631029] ? oom_kill_process+0x396/0x400 [ 249.632039] ? __next_timer_interrupt+0xc0/0xc0 [ 249.633087] schedule_timeout_killable+0x15/0x20 [ 249.634097] out_of_memory+0xea/0x270 [ 249.634901] __alloc_pages_nodemask+0x715/0x880 [ 249.635920] handle_mm_fault+0x538/0xe40 [ 249.636888] ? __enqueue_entity+0x63/0x70 [ 249.637787] ? set_next_entity+0x4b/0x80 [ 249.638687] __do_page_fault+0x199/0x430 [ 249.639535] ? vmalloc_sync_all+0x180/0x180 [ 249.640452] do_page_fault+0x1a/0x1e [ 249.641283] common_exception+0x82/0x8a (...snipped...) [ 462.676366] oom_reaper: reaped process 1191 (b.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB -------------------- -------------------- [ 269.985819] b.out invoked oom-killer: gfp_mask=0x14200ca(GFP_HIGHUSER_MOVABLE), nodemask=(null), order=0, oom_score_adj=0 [ 269.988570] CPU: 0 PID: 9079 Comm: b.out Not tainted 4.15.0-rc8+ torvalds#217 (...snipped...) [ 270.073050] Out of memory: Kill process 914 (b.out) score 9 or sacrifice child [ 270.074660] Killed process 2208 (b.out) total-vm:2108kB, anon-rss:64kB, file-rss:4kB, shmem-rss:0kB [ 297.562824] sysrq: SysRq : Show State (...snipped...) [ 471.716610] b.out R running task 0 9079 7400 0x00000000 [ 471.718203] Call Trace: [ 471.718784] __schedule+0x142/0x4b2 [ 471.719577] schedule+0x27/0x70 [ 471.720294] schedule_timeout+0xd1/0x160 [ 471.721207] ? oom_kill_process+0x396/0x400 [ 471.722151] ? __next_timer_interrupt+0xc0/0xc0 [ 471.723215] schedule_timeout_killable+0x15/0x20 [ 471.724350] out_of_memory+0xea/0x270 [ 471.725201] __alloc_pages_nodemask+0x715/0x880 [ 471.726238] ? radix_tree_lookup_slot+0x1f/0x50 [ 471.727253] filemap_fault+0x346/0x510 [ 471.728120] ? filemap_map_pages+0x245/0x2d0 [ 471.729105] ? unlock_page+0x30/0x30 [ 471.729987] __xfs_filemap_fault.isra.18+0x2d/0xb0 [ 471.731488] ? unlock_page+0x30/0x30 [ 471.732364] xfs_filemap_fault+0xa/0x10 [ 471.733260] __do_fault+0x11/0x30 [ 471.734033] handle_mm_fault+0x8e8/0xe40 [ 471.735200] __do_page_fault+0x199/0x430 [ 471.736163] ? common_exception+0x82/0x8a [ 471.737102] ? vmalloc_sync_all+0x180/0x180 [ 471.738061] do_page_fault+0x1a/0x1e [ 471.738881] common_exception+0x82/0x8a (...snipped...) [ 566.969400] oom_reaper: reaped process 2208 (b.out), now anon-rss:0kB, file-rss:0kB, shmem-rss:0kB -------------------- Allowing the OOM reaper to start reclaiming memory without waiting for the oom_lock is not sufficient if the OOM reaper did not reclaim enough memory. We need to make sure that the thread which called out_of_memory() will release oom_lock shortly. Thus, this patch brings the short sleep to outside of the OOM killer. For __alloc_pages_may_oom() case, this patch uses uninterruptible sleep than killable sleep because fatal_signal_pending() threads won't be able to use memory reserves unless tsk_is_oom_victim() becomes true. Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Roman Gushchin <guro@fb.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: David Rientjes <rientjes@google.com> Cc: Tejun Heo <tj@kernel.org>
0day-ci · Jan 24, 2018 · c3a7eca · c3a7eca
1 parent d67adaa
commit c3a7eca
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Showing 2 changed files with 5 additions and 16 deletions.
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
@@ -1078,7 +1078,6 @@ bool out_of_memory(struct oom_control *oc)
 {
 	unsigned long freed = 0;
 	enum oom_constraint constraint = CONSTRAINT_NONE;
-	bool delay = false; /* if set, delay next allocation attempt */
 
 	if (oom_killer_disabled)
 		return false;
@@ -1128,31 +1127,19 @@ bool out_of_memory(struct oom_control *oc)
 		return true;
 	}
 
-	if (mem_cgroup_select_oom_victim(oc) && oom_kill_memcg_victim(oc)) {
-		delay = true;
+	if (mem_cgroup_select_oom_victim(oc) && oom_kill_memcg_victim(oc))
 		goto out;
-	}
 
 	select_bad_process(oc);
 	/* Found nothing?!?! Either we hang forever, or we panic. */
 	if (!oc->chosen_task && !is_sysrq_oom(oc) && !is_memcg_oom(oc)) {
 		dump_header(oc, NULL);
 		panic("Out of memory and no killable processes...\n");
 	}
-	if (oc->chosen_task && oc->chosen_task != INFLIGHT_VICTIM) {
+	if (oc->chosen_task && oc->chosen_task != INFLIGHT_VICTIM)
 		oom_kill_process(oc, !is_memcg_oom(oc) ? "Out of memory" :
 				 "Memory cgroup out of memory");
-		delay = true;
-	}
-
 out:
-	/*
-	 * Give the killed process a good chance to exit before trying
-	 * to allocate memory again.
-	 */
-	if (delay)
-		schedule_timeout_killable(1);
-
 	return !!oc->chosen_task;
 }
 
@@ -1178,4 +1165,5 @@ void pagefault_out_of_memory(void)
 		return;
 	out_of_memory(&oc);
 	mutex_unlock(&oom_lock);
+	schedule_timeout_killable(1);
 }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
@@ -3355,7 +3355,6 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
 	 */
 	if (!mutex_trylock(&oom_lock)) {
 		*did_some_progress = 1;
-		schedule_timeout_uninterruptible(1);
 		return NULL;
 	}
 
@@ -4116,6 +4115,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 	/* Retry as long as the OOM killer is making progress */
 	if (did_some_progress) {
 		no_progress_loops = 0;
+		if (!tsk_is_oom_victim(current))
+			schedule_timeout_uninterruptible(1);
 		goto retry;
 	}