Michal, before we think about whether to add preempt_disable()/preempt_enable_no_resched()
to oom_kill_process(), will you accept this patch?
This is one of problems which annoy kmallocwd patch on CONFIG_PREEMPT_NONE=y kernels.
---------- sleep-with-oom_lock.c start ----------
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sched.h>
#include <signal.h>
#include <sys/prctl.h>
int main(int argc, char *argv[])
{
struct sched_param sp = { 0 };
cpu_set_t cpu = { { 1 } };
static int pipe_fd[2] = { EOF, EOF };
char *buf = NULL;
unsigned long size = 0;
unsigned int i;
int fd;
pipe(pipe_fd);
signal(SIGCLD, SIG_IGN);
if (fork() == 0) {
prctl(PR_SET_NAME, (unsigned long) "first-victim", 0, 0, 0);
while (1)
pause();
}
close(pipe_fd[1]);
sched_setaffinity(0, sizeof(cpu), &cpu);
prctl(PR_SET_NAME, (unsigned long) "normal-priority", 0, 0, 0);
for (i = 0; i < 64; i++)
if (fork() == 0) {
char c;
/* Wait until the first-victim is OOM-killed. */
read(pipe_fd[0], &c, 1);
/* Try to consume as much CPU time as possible. */
while(1);
_exit(0);
}
close(pipe_fd[0]);
fd = open("/dev/zero", O_RDONLY);
for (size = 1048576; size < 512UL * (1 << 30); size <<= 1) {
char *cp = realloc(buf, size);
if (!cp) {
size >>= 1;
break;
}
buf = cp;
}
sched_setscheduler(0, SCHED_IDLE, &sp);
prctl(PR_SET_NAME, (unsigned long) "idle-priority", 0, 0, 0);
read(fd, buf, size); /* Will cause OOM due to overcommit */
kill(-1, SIGKILL);
return 0; /* Not reached. */
}
---------- sleep-with-oom_lock.c end ----------
---------- console log start ----------
[ 915.132305] CPU: 0 PID: 1341 Comm: idle-priority Not tainted 4.5.0-rc6-next-20160301 #89
[ 915.137977] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/31/2013
[ 915.144914] 0000000000000286 0000000000291f95 ffff88003b06f860 ffffffff8131424d
[ 915.150071] 0000000000000000 ffff88003b06fa98 ffff88003b06f900 ffffffff811b9934
[ 915.155231] 0000000000000206 ffffffff8182b7b0 ffff88003b06f8a0 ffffffff810bae39
[ 915.160540] Call Trace:
[ 915.162963] [<ffffffff8131424d>] dump_stack+0x85/0xc8
[ 915.166689] [<ffffffff811b9934>] dump_header+0x5b/0x394
[ 915.170509] [<ffffffff810bae39>] ? trace_hardirqs_on_caller+0xf9/0x1c0
[ 915.175324] [<ffffffff810baf0d>] ? trace_hardirqs_on+0xd/0x10
[ 915.179497] [<ffffffff81142286>] oom_kill_process+0x376/0x570
[ 915.183661] [<ffffffff811426d6>] out_of_memory+0x206/0x5a0
[ 915.187651] [<ffffffff81142794>] ? out_of_memory+0x2c4/0x5a0
[ 915.191706] [<ffffffff811485b2>] __alloc_pages_nodemask+0xbe2/0xd90
[ 915.196124] [<ffffffff811934d6>] alloc_pages_vma+0xb6/0x290
[ 915.200128] [<ffffffff81170af8>] handle_mm_fault+0x12d8/0x16f0
[ 915.204299] [<ffffffff8116f868>] ? handle_mm_fault+0x48/0x16f0
[ 915.208467] [<ffffffff8105c089>] ? __do_page_fault+0x129/0x4f0
[ 915.212599] [<ffffffff8105c127>] __do_page_fault+0x1c7/0x4f0
[ 915.216653] [<ffffffff8105c480>] do_page_fault+0x30/0x80
[ 915.220447] [<ffffffff81669668>] page_fault+0x28/0x30
[ 915.224311] [<ffffffff81321f0d>] ? __clear_user+0x3d/0x70
[ 915.228155] [<ffffffff81321eee>] ? __clear_user+0x1e/0x70
[ 915.231988] [<ffffffff81326a98>] iov_iter_zero+0x68/0x250
[ 915.235771] [<ffffffff81400ed8>] read_iter_zero+0x38/0xa0
[ 915.239517] [<ffffffff811bd934>] __vfs_read+0xc4/0xf0
[ 915.243041] [<ffffffff811be49a>] vfs_read+0x7a/0x120
[ 915.246526] [<ffffffff811bed43>] SyS_read+0x53/0xd0
[ 915.249922] [<ffffffff8100364d>] do_syscall_64+0x5d/0x180
[ 915.253613] [<ffffffff81667bff>] entry_SYSCALL64_slow_path+0x25/0x25
(...snipped...)
[ 915.410964] Out of memory: Kill process 1341 (idle-priority) score 846 or sacrifice child
[ 915.416430] Killed process 1347 (normal-priority) total-vm:4172kB, anon-rss:80kB, file-rss:0kB, shmem-rss:0kB
(...snipped...)
[ 1066.855742] idle-priority R running task 0 1341 1316 0x00000080
[ 1066.861076] ffff88003b06f898 ffff88003eb74080 ffff880039f3a000 ffff88003b070000
[ 1066.866715] ffff88003b06f8d0 ffff88003c610240 000000010009635f ffffffff81c0dbd8
[ 1066.872338] ffff88003b06f8b0 ffffffff81662ce0 ffff88003c610240 ffff88003b06f958
[ 1066.877976] Call Trace:
[ 1066.880120] [<ffffffff81662ce0>] schedule+0x30/0x80
[ 1066.883963] [<ffffffff81666d17>] schedule_timeout+0x117/0x1c0
[ 1066.888391] [<ffffffff810dda00>] ? init_timer_key+0x40/0x40
[ 1066.892675] [<ffffffff81666df9>] schedule_timeout_killable+0x19/0x20
[ 1066.897518] [<ffffffff811426e0>] out_of_memory+0x210/0x5a0
[ 1066.901779] [<ffffffff81142794>] ? out_of_memory+0x2c4/0x5a0
[ 1066.906153] [<ffffffff811485b2>] __alloc_pages_nodemask+0xbe2/0xd90
[ 1066.910965] [<ffffffff811934d6>] alloc_pages_vma+0xb6/0x290
[ 1066.915371] [<ffffffff81170af8>] handle_mm_fault+0x12d8/0x16f0
[ 1066.919868] [<ffffffff8116f868>] ? handle_mm_fault+0x48/0x16f0
[ 1066.924457] [<ffffffff8105c089>] ? __do_page_fault+0x129/0x4f0
[ 1066.929197] [<ffffffff8105c127>] __do_page_fault+0x1c7/0x4f0
[ 1066.933805] [<ffffffff8105c480>] do_page_fault+0x30/0x80
[ 1066.938236] [<ffffffff81669668>] page_fault+0x28/0x30
[ 1066.942352] [<ffffffff81321f0d>] ? __clear_user+0x3d/0x70
[ 1066.946536] [<ffffffff81321eee>] ? __clear_user+0x1e/0x70
[ 1066.950707] [<ffffffff81326a98>] iov_iter_zero+0x68/0x250
[ 1066.954920] [<ffffffff81400ed8>] read_iter_zero+0x38/0xa0
[ 1066.959044] [<ffffffff811bd934>] __vfs_read+0xc4/0xf0
[ 1066.962965] [<ffffffff811be49a>] vfs_read+0x7a/0x120
[ 1066.966825] [<ffffffff811bed43>] SyS_read+0x53/0xd0
[ 1066.970615] [<ffffffff8100364d>] do_syscall_64+0x5d/0x180
[ 1066.974741] [<ffffffff81667bff>] entry_SYSCALL64_slow_path+0x25/0x25
(...snipped...)
[ 1312.850193] sysrq: SysRq : Manual OOM execution
[ 1440.303946] INFO: task kworker/3:1:46 blocked for more than 120 seconds.
[ 1440.309844] Not tainted 4.5.0-rc6-next-20160301 #89
[ 1440.314332] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1440.320536] kworker/3:1 D ffff880039217ca8 0 46 2 0x00000000
[ 1440.326079] Workqueue: events moom_callback
[ 1440.329612] ffff880039217ca8 ffff88003be120c0 ffff880039212000 ffff880039218000
[ 1440.335436] ffffffff81c7a568 0000000000000246 ffff880039212000 00000000ffffffff
[ 1440.341197] ffff880039217cc0 ffffffff81662ce0 ffffffff81c7a560 ffff880039217cd0
[ 1440.347021] Call Trace:
[ 1440.349347] [<ffffffff81662ce0>] schedule+0x30/0x80
[ 1440.353419] [<ffffffff81662fe9>] schedule_preempt_disabled+0x9/0x10
[ 1440.358324] [<ffffffff81664b9f>] mutex_lock_nested+0x14f/0x3a0
[ 1440.362667] [<ffffffff813e3f6e>] ? moom_callback+0x6e/0xb0
[ 1440.367123] [<ffffffff813e3f6e>] moom_callback+0x6e/0xb0
[ 1440.371381] [<ffffffff8108a955>] process_one_work+0x1a5/0x400
[ 1440.375863] [<ffffffff8108a8f1>] ? process_one_work+0x141/0x400
[ 1440.380475] [<ffffffff8108acd6>] worker_thread+0x126/0x490
[ 1440.384827] [<ffffffff816625a4>] ? __schedule+0x314/0xa20
[ 1440.389139] [<ffffffff8108abb0>] ? process_one_work+0x400/0x400
[ 1440.393820] [<ffffffff81090c9e>] kthread+0xee/0x110
[ 1440.397749] [<ffffffff81667d72>] ret_from_fork+0x22/0x50
[ 1440.401950] [<ffffffff81090bb0>] ? kthread_create_on_node+0x230/0x230
[ 1440.406862] 3 locks held by kworker/3:1/46:
[ 1440.410200] #0: ("events"){.+.+.+}, at: [<ffffffff8108a8f1>] process_one_work+0x141/0x400
[ 1440.417208] #1: (moom_work){+.+...}, at: [<ffffffff8108a8f1>] process_one_work+0x141/0x400
[ 1440.423539] #2: (oom_lock){+.+...}, at: [<ffffffff813e3f6e>] moom_callback+0x6e/0xb0
(...snipped...)
[ 1525.328487] idle-priority R running task 0 1341 1316 0x00000080
[ 1525.333576] ffff88003b06f898 ffff88003eb74080 ffff880039f3a000 ffff88003b070000
[ 1525.339361] ffff88003b06f8d0 ffff88003c610240 000000010009635f ffffffff81c0dbd8
[ 1525.344851] ffff88003b06f8b0 ffffffff81662ce0 ffff88003c610240 ffff88003b06f958
[ 1525.350410] Call Trace:
[ 1525.352698] [<ffffffff81662ce0>] schedule+0x30/0x80
[ 1525.356262] [<ffffffff81666d17>] schedule_timeout+0x117/0x1c0
[ 1525.360557] [<ffffffff810dda00>] ? init_timer_key+0x40/0x40
[ 1525.365088] [<ffffffff81666df9>] schedule_timeout_killable+0x19/0x20
[ 1525.370150] [<ffffffff811426e0>] out_of_memory+0x210/0x5a0
[ 1525.374496] [<ffffffff81142794>] ? out_of_memory+0x2c4/0x5a0
[ 1525.378937] [<ffffffff811485b2>] __alloc_pages_nodemask+0xbe2/0xd90
[ 1525.383811] [<ffffffff811934d6>] alloc_pages_vma+0xb6/0x290
[ 1525.388206] [<ffffffff81170af8>] handle_mm_fault+0x12d8/0x16f0
[ 1525.392782] [<ffffffff8116f868>] ? handle_mm_fault+0x48/0x16f0
[ 1525.397338] [<ffffffff8105c089>] ? __do_page_fault+0x129/0x4f0
[ 1525.401933] [<ffffffff8105c127>] __do_page_fault+0x1c7/0x4f0
[ 1525.406370] [<ffffffff8105c480>] do_page_fault+0x30/0x80
[ 1525.410542] [<ffffffff81669668>] page_fault+0x28/0x30
[ 1525.414698] [<ffffffff81321f0d>] ? __clear_user+0x3d/0x70
[ 1525.418921] [<ffffffff81321eee>] ? __clear_user+0x1e/0x70
[ 1525.423132] [<ffffffff81326a98>] iov_iter_zero+0x68/0x250
[ 1525.427384] [<ffffffff81400ed8>] read_iter_zero+0x38/0xa0
[ 1525.431592] [<ffffffff811bd934>] __vfs_read+0xc4/0xf0
[ 1525.435548] [<ffffffff811be49a>] vfs_read+0x7a/0x120
[ 1525.439440] [<ffffffff811bed43>] SyS_read+0x53/0xd0
[ 1525.443259] [<ffffffff8100364d>] do_syscall_64+0x5d/0x180
[ 1525.447420] [<ffffffff81667bff>] entry_SYSCALL64_slow_path+0x25/0x25
(...snipped...)
[ 1560.429708] INFO: task kworker/3:1:46 blocked for more than 120 seconds.
[ 1560.435640] Not tainted 4.5.0-rc6-next-20160301 #89
[ 1560.440208] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1560.446115] kworker/3:1 D ffff880039217ca8 0 46 2 0x00000000
[ 1560.451572] Workqueue: events moom_callback
[ 1560.455045] ffff880039217ca8 ffff88003be120c0 ffff880039212000 ffff880039218000
[ 1560.460769] ffffffff81c7a568 0000000000000246 ffff880039212000 00000000ffffffff
[ 1560.466530] ffff880039217cc0 ffffffff81662ce0 ffffffff81c7a560 ffff880039217cd0
[ 1560.472363] Call Trace:
[ 1560.474603] [<ffffffff81662ce0>] schedule+0x30/0x80
[ 1560.478892] [<ffffffff81662fe9>] schedule_preempt_disabled+0x9/0x10
[ 1560.483713] [<ffffffff81664b9f>] mutex_lock_nested+0x14f/0x3a0
[ 1560.488398] [<ffffffff813e3f6e>] ? moom_callback+0x6e/0xb0
[ 1560.492703] [<ffffffff813e3f6e>] moom_callback+0x6e/0xb0
[ 1560.496938] [<ffffffff8108a955>] process_one_work+0x1a5/0x400
[ 1560.501391] [<ffffffff8108a8f1>] ? process_one_work+0x141/0x400
[ 1560.505944] [<ffffffff8108acd6>] worker_thread+0x126/0x490
[ 1560.510173] [<ffffffff816625a4>] ? __schedule+0x314/0xa20
[ 1560.514330] [<ffffffff8108abb0>] ? process_one_work+0x400/0x400
[ 1560.518899] [<ffffffff81090c9e>] kthread+0xee/0x110
[ 1560.522760] [<ffffffff81667d72>] ret_from_fork+0x22/0x50
[ 1560.526923] [<ffffffff81090bb0>] ? kthread_create_on_node+0x230/0x230
[ 1560.531792] 3 locks held by kworker/3:1/46:
[ 1560.535086] #0: ("events"){.+.+.+}, at: [<ffffffff8108a8f1>] process_one_work+0x141/0x400
[ 1560.541351] #1: (moom_work){+.+...}, at: [<ffffffff8108a8f1>] process_one_work+0x141/0x400
[ 1560.547626] #2: (oom_lock){+.+...}, at: [<ffffffff813e3f6e>] moom_callback+0x6e/0xb0
[ 1582.487749] sysrq: SysRq : Kill All Tasks
[ 1582.530799] kworker/3:1 invoked oom-killer: gfp_mask=0x24000c0(GFP_KERNEL), order=-1, oom_score_adj=0
[ 1582.538355] kworker/3:1 cpuset=/ mems_allowed=0
[ 1582.570304] CPU: 3 PID: 46 Comm: kworker/3:1 Not tainted 4.5.0-rc6-next-20160301 #89
---------- console log end ----------
Complete log is at http://I-love.SAKURA.ne.jp/tmp/serial-20160303.txt.xz .
------------------------------------------------------------
>From 92d4ec39ed23c6d0d5785f4f53311d55dfe480de Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 3 Mar 2016 13:27:06 +0900
Subject: [PATCH] mm,oom: Do not sleep with oom_lock held.
out_of_memory() can stall effectively forever if a SCHED_IDLE thread
called out_of_memory() when there are !SCHED_IDLE threads running on
the same CPU, for schedule_timeout_killable(1) cannot return shortly
due to scheduling priority.
Operations with oom_lock held should complete as soon as possible
because we might be preserving OOM condition for most of that period
if we are in OOM condition. SysRq-f can't work if oom_lock is held.
It would be possible to boost scheduling priority of current thread
while holding oom_lock, but priority of current thread might be
manipulated by other threads after boosting. Unless we offload
operations with oom_lock held to a dedicated kernel thread with high
priority, addressing this problem using priority manipulation is racy.
This patch brings schedule_timeout_killable(1) out of oom_lock.
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
mm/oom_kill.c | 8 +-------
mm/page_alloc.c | 34 +++++++++++++++++++++++-----------
2 files changed, 24 insertions(+), 18 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 5d5eca9..dbef3a7 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -901,15 +901,9 @@ bool out_of_memory(struct oom_control *oc)
dump_header(oc, NULL, NULL);
panic("Out of memory and no killable processes...\n");
}
- if (p && p != (void *)-1UL) {
+ if (p && p != (void *)-1UL)
oom_kill_process(oc, p, points, totalpages, NULL,
"Out of memory");
- /*
- * Give the killed process a good chance to exit before trying
- * to allocate memory again.
- */
- schedule_timeout_killable(1);
- }
return true;
}
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1993894..cfe0997 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2871,20 +2871,32 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order,
goto out;
}
/* Exhausted what can be done so it's blamo time */
- if (out_of_memory(&oc) || WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
+ if (out_of_memory(&oc)) {
+ mutex_unlock(&oom_lock);
+ *did_some_progress = 1;
+ /*
+ * Give the killed process a good chance to exit before trying
+ * to allocate memory again. We should sleep after releasing
+ * oom_lock because current thread might be SCHED_IDLE priority
+ * which can sleep for minutes when preempted by other threads
+ * with !SCHED_IDLE priority running on the same CPU.
+ */
+ schedule_timeout_killable(1);
+ return NULL;
+ }
+ if (WARN_ON_ONCE(gfp_mask & __GFP_NOFAIL)) {
*did_some_progress = 1;
- if (gfp_mask & __GFP_NOFAIL) {
+ page = get_page_from_freelist(gfp_mask, order,
+ ALLOC_NO_WATERMARKS|ALLOC_CPUSET,
+ ac);
+ /*
+ * fallback to ignore cpuset restriction if our nodes
+ * are depleted
+ */
+ if (!page)
page = get_page_from_freelist(gfp_mask, order,
- ALLOC_NO_WATERMARKS|ALLOC_CPUSET, ac);
- /*
- * fallback to ignore cpuset restriction if our nodes
- * are depleted
- */
- if (!page)
- page = get_page_from_freelist(gfp_mask, order,
- ALLOC_NO_WATERMARKS, ac);
- }
+ ALLOC_NO_WATERMARKS, ac);
}
out:
mutex_unlock(&oom_lock);
--
1.8.3.1
--
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