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Commit b52723c5 authored by KOSAKI Motohiro's avatar KOSAKI Motohiro Committed by Linus Torvalds
Browse files

oom: fix tasklist_lock leak 



Commit 0aad4b31 ("oom: fold __out_of_memory into out_of_memory")
introduced a tasklist_lock leak.  Then it caused following obvious
danger warnings and panic.

    ================================================
    [ BUG: lock held when returning to user space! ]
    ------------------------------------------------
    rsyslogd/1422 is leaving the kernel with locks still held!
    1 lock held by rsyslogd/1422:
     #0:  (tasklist_lock){.+.+.+}, at: [<ffffffff810faf64>] out_of_memory+0x164/0x3f0
    BUG: scheduling while atomic: rsyslogd/1422/0x00000002
    INFO: lockdep is turned off.

This patch fixes it.

Signed-off-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: default avatarMinchan Kim <minchan.kim@gmail.com>
Acked-by: default avatarDavid Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent be71cf22

mm/oom_kill.c

+6 −3
Original line number Diff line number Diff line
@@ -646,6 +646,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, 
	unsigned long freed = 0;

	unsigned int points;

	enum oom_constraint constraint = CONSTRAINT_NONE;

	int killed = 0;



	blocking_notifier_call_chain(&oom_notify_list, 0, &freed);

	if (freed > 0)
@@ -683,7 +684,7 @@ void out_of_memory(struct zonelist *zonelist, gfp_t gfp_mask, 
		if (!oom_kill_process(current, gfp_mask, order, 0, totalpages,

				NULL, nodemask,

				"Out of memory (oom_kill_allocating_task)"))

			return;

			goto out;

	}



retry:
@@ -691,7 +692,7 @@ retry: 
			constraint == CONSTRAINT_MEMORY_POLICY ? nodemask :

								 NULL);

	if (PTR_ERR(p) == -1UL)

		return;

		goto out;



	/* Found nothing?!?! Either we hang forever, or we panic. */

	if (!p) {
@@ -703,13 +704,15 @@ retry: 
	if (oom_kill_process(p, gfp_mask, order, points, totalpages, NULL,

				nodemask, "Out of memory"))

		goto retry;

	killed = 1;

out:

	read_unlock(&tasklist_lock);



	/*

	 * Give "p" a good chance of killing itself before we

	 * retry to allocate memory unless "p" is current

	 */

	if (!test_thread_flag(TIF_MEMDIE))

	if (killed && !test_thread_flag(TIF_MEMDIE))

		schedule_timeout_uninterruptible(1);

}