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Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks

From Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Newsgroups linux.kernel
Subject Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks
Date 2015-09-22 07:40 +0200
Message-ID <qbot3-4wd-5@gated-at.bofh.it> (permalink)
References <qa6HV-7Th-75@gated-at.bofh.it> <qa7kB-pY-3@gated-at.bofh.it> <qalQB-4Aq-7@gated-at.bofh.it> <qart0-48K-15@gated-at.bofh.it> <qbiQF-4KR-11@gated-at.bofh.it>
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David Rientjes wrote:
> Your proposal, which I mostly agree with, tries to kill additional 
> processes so that they allocate and drop the lock that the original victim 
> depends on.  My approach, from 
> http://marc.info/?l=linux-kernel&m=144010444913702, is the same, but 
> without the killing.  It's unecessary to kill every process on the system 
> that is depending on the same lock, and we can't know which processes are 
> stalling on that lock and which are not.

Would you try your approach with below program?
(My reproducers are tested on XFS on a VM with 4 CPUs / 2048MB RAM.)

---------- oom-depleter3.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>

static int zero_fd = EOF;
static char *buf = NULL;
static unsigned long size = 0;

static int dummy(void *unused)
{
	static char buffer[4096] = { };
	int fd = open("/tmp/file", O_WRONLY | O_CREAT | O_APPEND, 0600);
	while (write(fd, buffer, sizeof(buffer) == sizeof(buffer)) &&
	       fsync(fd) == 0);
	return 0;
}

static int trigger(void *unused)
{
	read(zero_fd, buf, size); /* Will cause OOM due to overcommit */
	return 0;
}

int main(int argc, char *argv[])
{
        unsigned long i;
	zero_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;
	}
	/*
	 * Create many child threads in order to enlarge time lag between
	 * the OOM killer sets TIF_MEMDIE to thread group leader and
	 * the OOM killer sends SIGKILL to that thread.
	 */
	for (i = 0; i < 1000; i++) {
		clone(dummy, malloc(1024) + 1024, CLONE_SIGHAND | CLONE_VM,
		      NULL);
	}
	/* Let a child thread trigger the OOM killer. */
	clone(trigger, malloc(4096)+ 4096, CLONE_SIGHAND | CLONE_VM, NULL);
	/* Deplete all memory reserve using the time lag. */
	for (i = size; i; i -= 4096)
		buf[i - 1] = 1;
	return * (char *) NULL; /* Kill all threads. */
}
---------- oom-depleter3.c end ----------

uptime > 350 of http://I-love.SAKURA.ne.jp/tmp/serial-20150922-1.txt.xz
shows that the memory reserves completely depleted and
uptime > 42 of http://I-love.SAKURA.ne.jp/tmp/serial-20150922-2.txt.xz
shows that the memory reserves was not used at all.
Is this result what you expected?
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Thread

[PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Kyle Walker <kwalker@redhat.com> - 2015-09-17 20:10 +0200
  Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Oleg Nesterov <oleg@redhat.com> - 2015-09-17 21:30 +0200
    Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Christoph Lameter <cl@linux.com> - 2015-09-18 17:50 +0200
      Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Oleg Nesterov <oleg@redhat.com> - 2015-09-18 18:30 +0200
        Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-18 18:50 +0200
          Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Oleg Nesterov <oleg@redhat.com> - 2015-09-18 19:00 +0200
        Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Christoph Lameter <cl@linux.com> - 2015-09-18 19:10 +0200
          Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Oleg Nesterov <oleg@redhat.com> - 2015-09-18 21:20 +0200
            Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Christoph Lameter <cl@linux.com> - 2015-09-18 21:20 +0200
              Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Christoph Lameter <cl@linux.com> - 2015-09-19 00:10 +0200
          Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Michal Hocko <mhocko@kernel.org> - 2015-09-19 10:40 +0200
            Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-19 16:40 +0200
              Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Michal Hocko <mhocko@kernel.org> - 2015-09-19 18:00 +0200
              Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks David Rientjes <rientjes@google.com> - 2015-09-22 01:40 +0200
                Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-22 07:40 +0200
                Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks David Rientjes <rientjes@google.com> - 2015-09-23 01:40 +0200
                Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Kyle Walker <kwalker@redhat.com> - 2015-09-23 14:10 +0200
                Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-24 14:00 +0200
            Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Oleg Nesterov <oleg@redhat.com> - 2015-09-19 16:50 +0200
          Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks David Rientjes <rientjes@google.com> - 2015-09-22 01:30 +0200
      Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Michal Hocko <mhocko@kernel.org> - 2015-09-19 10:30 +0200
  Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks Michal Hocko <mhocko@kernel.org> - 2015-09-19 10:30 +0200
    Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks David Rientjes <rientjes@google.com> - 2015-09-22 01:10 +0200
  can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-19 17:10 +0200
    Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-19 17:20 +0200
    Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-09-19 18:00 +0200
      Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-20 15:20 +0200
    Re: can't oom-kill zap the victim's memory? Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-20 00:30 +0200
      Re: can't oom-kill zap the victim's memory? Raymond Jennings <shentino@gmail.com> - 2015-09-20 01:10 +0200
        Re: can't oom-kill zap the victim's memory? Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-20 01:20 +0200
      Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-09-20 11:40 +0200
        Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-20 15:10 +0200
      Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-20 15:10 +0200
        Re: can't oom-kill zap the victim's memory? Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-20 20:10 +0200
          Re: can't oom-kill zap the victim's memory? Raymond Jennings <shentino@gmail.com> - 2015-09-20 21:10 +0200
            Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-21 16:10 +0200
          Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-21 15:50 +0200
            Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-09-21 16:30 +0200
              Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-21 17:40 +0200
                Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-09-21 18:20 +0200
                Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-22 18:10 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-23 01:10 +0200
                Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-09-23 23:00 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-24 23:20 +0200
                Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-09-25 11:40 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-25 18:20 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-28 18:20 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-29 00:30 +0200
                Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-10-02 14:40 +0200
                Re: can't oom-kill zap the victim's memory? Linus Torvalds <torvalds@linux-foundation.org> - 2015-10-02 21:10 +0200
                Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-10-05 16:50 +0200
                Can't we use timeout based OOM warning/killing? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-03 08:10 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-29 00:30 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-29 10:00 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-30 01:00 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-30 06:30 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-30 12:30 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-30 23:20 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-01 14:20 +0200
                Re: can't oom-kill zap the victim's memory? Michal Hocko <mhocko@kernel.org> - 2015-10-01 16:50 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-10-02 15:10 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-21 19:00 +0200
                Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-22 14:50 +0200
                Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-22 16:40 +0200
                Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-22 16:50 +0200
                Re: can't oom-kill zap the victim's memory? David Rientjes <rientjes@google.com> - 2015-09-22 01:50 +0200
            Re: can't oom-kill zap the victim's memory? Linus Torvalds <torvalds@linux-foundation.org> - 2015-09-21 19:00 +0200
    Re: can't oom-kill zap the victim's memory? Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> - 2015-09-20 17:00 +0200
      Re: can't oom-kill zap the victim's memory? Oleg Nesterov <oleg@redhat.com> - 2015-09-20 17:00 +0200

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