[PATCH] mm,oom: Exclude TIF_MEMDIE processes from candidates.

From: Tetsuo Handa
Date: Tue Dec 29 2015 - 08:58:31 EST

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>From 8bb9e36891a803e82c589ef78077838026ce0f7d Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Tue, 29 Dec 2015 22:20:58 +0900
Subject: [PATCH] mm,oom: Exclude TIF_MEMDIE processes from candidates.

The OOM reaper kernel thread can reclaim OOM victim's memory before the victim
terminates. But since oom_kill_process() tries to kill children of the memory
hog process first, the OOM reaper can not reclaim enough memory for terminating
the victim if the victim is consuming little memory. The result is OOM livelock
as usual, for timeout based next OOM victim selection is not implemented.

While SysRq-f (manual invocation of the OOM killer) can wake up the OOM killer,
the OOM killer chooses the same OOM victim which already has TIF_MEMDIE. This
is effectively disabling SysRq-f.

This patch excludes TIF_MEMDIE processes from candidates so that the memory
hog process itself will be killed when all children of the memory hog process
got stuck with TIF_MEMDIE pending.

----------
[ 120.078776] oom-write invoked oom-killer: order=0, oom_score_adj=0, gfp_mask=0x24280ca(GFP_HIGHUSER_MOVABLE|GFP_ZERO)
[ 120.088610] oom-write cpuset=/ mems_allowed=0
[ 120.095558] CPU: 0 PID: 9546 Comm: oom-write Not tainted 4.4.0-rc6-next-20151223 #260
(...snipped...)
[ 120.194148] [ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name
(...snipped...)
[ 120.260191] [ 9546] 1000 9546 541716 453473 896 6 0 0 oom-write
[ 120.262166] [ 9547] 1000 9547 40 1 3 2 0 0 write
[ 120.264071] [ 9548] 1000 9548 40 1 3 2 0 0 write
[ 120.265939] [ 9549] 1000 9549 40 1 4 2 0 0 write
[ 120.267794] [ 9550] 1000 9550 40 1 3 2 0 0 write
[ 120.269654] [ 9551] 1000 9551 40 1 3 2 0 0 write
[ 120.271447] [ 9552] 1000 9552 40 1 3 2 0 0 write
[ 120.273220] [ 9553] 1000 9553 40 1 3 2 0 0 write
[ 120.274975] [ 9554] 1000 9554 40 1 3 2 0 0 write
[ 120.276745] [ 9555] 1000 9555 40 1 3 2 0 0 write
[ 120.278516] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 120.280227] Out of memory: Kill process 9546 (oom-write) score 892 or sacrifice child
[ 120.282010] Killed process 9549 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
(...snipped...)
[ 122.506001] systemd-journal invoked oom-killer: order=0, oom_score_adj=0, gfp_mask=0x24201ca(GFP_HIGHUSER_MOVABLE|GFP_COLD)
[ 122.515041] systemd-journal cpuset=/ mems_allowed=0
(...snipped...)
[ 122.697515] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 122.699492] [ 9551] 1000 9551 40 1 3 2 0 0 write
[ 122.701399] [ 9552] 1000 9552 40 1 3 2 0 0 write
[ 122.703282] [ 9553] 1000 9553 40 1 3 2 0 0 write
[ 122.705188] [ 9554] 1000 9554 40 1 3 2 0 0 write
[ 122.707017] [ 9555] 1000 9555 40 1 3 2 0 0 write
[ 122.708842] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 122.710675] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 122.712475] Killed process 9551 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[ 139.606508] sysrq: SysRq : Manual OOM execution
[ 139.612371] kworker/0:2 invoked oom-killer: order=-1, oom_score_adj=0, gfp_mask=0x24000c0(GFP_KERNEL)
[ 139.620210] kworker/0:2 cpuset=/ mems_allowed=0
(...snipped...)
[ 139.795759] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 139.797649] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 139.799526] [ 9552] 1000 9552 40 1 3 2 0 0 write
[ 139.801368] [ 9553] 1000 9553 40 1 3 2 0 0 write
[ 139.803249] [ 9554] 1000 9554 40 1 3 2 0 0 write
[ 139.805020] [ 9555] 1000 9555 40 1 3 2 0 0 write
[ 139.806799] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 139.808524] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 139.810216] Killed process 9552 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
(...snipped...)
[ 142.571815] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 142.573840] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 142.575754] [ 9552] 1000 9552 40 0 3 2 0 0 write
[ 142.577633] [ 9553] 1000 9553 40 1 3 2 0 0 write
[ 142.579433] [ 9554] 1000 9554 40 1 3 2 0 0 write
[ 142.581250] [ 9555] 1000 9555 40 1 3 2 0 0 write
[ 142.583003] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 142.585055] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 142.586796] Killed process 9553 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[ 143.599058] sysrq: SysRq : Manual OOM execution
[ 143.604300] kworker/0:2 invoked oom-killer: order=-1, oom_score_adj=0, gfp_mask=0x24000c0(GFP_KERNEL)
(...snipped...)
[ 143.783739] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 143.785691] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 143.787532] [ 9552] 1000 9552 40 0 3 2 0 0 write
[ 143.789377] [ 9553] 1000 9553 40 0 3 2 0 0 write
[ 143.791172] [ 9554] 1000 9554 40 1 3 2 0 0 write
[ 143.792985] [ 9555] 1000 9555 40 1 3 2 0 0 write
[ 143.794730] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 143.796723] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 143.798338] Killed process 9554 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[ 144.374525] sysrq: SysRq : Manual OOM execution
[ 144.379779] kworker/0:2 invoked oom-killer: order=-1, oom_score_adj=0, gfp_mask=0x24000c0(GFP_KERNEL)
(...snipped...)
[ 144.560718] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 144.562657] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 144.564560] [ 9552] 1000 9552 40 0 3 2 0 0 write
[ 144.566369] [ 9553] 1000 9553 40 0 3 2 0 0 write
[ 144.568246] [ 9554] 1000 9554 40 0 3 2 0 0 write
[ 144.570001] [ 9555] 1000 9555 40 1 3 2 0 0 write
[ 144.571794] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 144.573502] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 144.575119] Killed process 9555 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[ 145.158485] sysrq: SysRq : Manual OOM execution
[ 145.163600] kworker/0:2 invoked oom-killer: order=-1, oom_score_adj=0, gfp_mask=0x24000c0(GFP_KERNEL)
(...snipped...)
[ 145.346059] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 145.348012] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 145.349954] [ 9552] 1000 9552 40 0 3 2 0 0 write
[ 145.351817] [ 9553] 1000 9553 40 0 3 2 0 0 write
[ 145.353701] [ 9554] 1000 9554 40 0 3 2 0 0 write
[ 145.355568] [ 9555] 1000 9555 40 0 3 2 0 0 write
[ 145.357319] [ 9556] 1000 9556 40 1 3 2 0 0 write
[ 145.359114] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 145.360733] Killed process 9556 (write) total-vm:160kB, anon-rss:4kB, file-rss:0kB, shmem-rss:0kB
[ 169.158408] sysrq: SysRq : Manual OOM execution
[ 169.163612] kworker/0:2 invoked oom-killer: order=-1, oom_score_adj=0, gfp_mask=0x24000c0(GFP_KERNEL)
(...snipped...)
[ 169.343115] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 169.345053] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 169.346884] [ 9552] 1000 9552 40 0 3 2 0 0 write
[ 169.348965] [ 9553] 1000 9553 40 0 3 2 0 0 write
[ 169.350893] [ 9554] 1000 9554 40 0 3 2 0 0 write
[ 169.352713] [ 9555] 1000 9555 40 0 3 2 0 0 write
[ 169.354551] [ 9556] 1000 9556 40 0 3 2 0 0 write
[ 169.356450] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 169.358105] Killed process 9551 (write) total-vm:160kB, anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
[ 178.950315] sysrq: SysRq : Manual OOM execution
[ 178.955560] kworker/0:2 invoked oom-killer: order=-1, oom_score_adj=0, gfp_mask=0x24000c0(GFP_KERNEL)
(...snipped...)
[ 179.140752] [ 9546] 1000 9546 541716 458687 906 6 0 0 oom-write
[ 179.142653] [ 9551] 1000 9551 40 0 3 2 0 0 write
[ 179.144997] [ 9552] 1000 9552 40 0 3 2 0 0 write
[ 179.146849] [ 9553] 1000 9553 40 0 3 2 0 0 write
[ 179.148654] [ 9554] 1000 9554 40 0 3 2 0 0 write
[ 179.150411] [ 9555] 1000 9555 40 0 3 2 0 0 write
[ 179.152291] [ 9556] 1000 9556 40 0 3 2 0 0 write
[ 179.154002] Out of memory: Kill process 9546 (oom-write) score 902 or sacrifice child
[ 179.155666] Killed process 9551 (write) total-vm:160kB, anon-rss:0kB, file-rss:0kB, shmem-rss:0kB
----------

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 12 ++++++++++++
1 file changed, 12 insertions(+)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 4b0a5d8..a1a0f39 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -111,6 +111,18 @@ struct task_struct *find_lock_task_mm(struct task_struct *p)

rcu_read_lock();

+ /*
+ * Treat the whole process p as unkillable when one of subthreads has
+ * TIF_MEMDIE pending. Otherwise, we may end up setting TIF_MEMDIE on
+ * the same victim forever (e.g. making SysRq-f unusable).
+ */
+ for_each_thread(p, t) {
+ if (likely(!test_tsk_thread_flag(t, TIF_MEMDIE)))
+ continue;
+ t = NULL;
+ goto found;
+ }
+
for_each_thread(p, t) {
task_lock(t);
if (likely(t->mm))
--
1.8.3.1
--
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Next message: Hannes Frederic Sowa: "Re: [PATCH] netconsole: Initialize after all core networking drivers"
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