Commit f87fb599 authored Jun 04, 2014 by Oleg Nesterov Committed by Linus Torvalds Jun 04, 2014

memcg: mm_update_next_owner() should skip kthreads



"Search through everything else" in mm_update_next_owner() can hit a
kthread which adopted this "mm" via use_mm(), it should not be used as
mm->owner.  Add the PF_KTHREAD check.

While at it, change this code to use for_each_process_thread() instead
of deprecated do_each_thread/while_each_thread.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Peter Chiang <pchiang@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent f7e2f7e8

kernel/exit.c

+4 −6

Original line number	Diff line number	Diff line
		@@ -395,14 +395,12 @@ void mm_update_next_owner(struct mm_struct *mm)
		}

		/*
		* Search through everything else. We should not get
		* here often
		* Search through everything else, we should not get here often.
		*/
		do_each_thread(g, c) {
		if (c->mm == mm)
		for_each_process_thread(g, c) {
		if (!(c->flags & PF_KTHREAD) && c->mm == mm)
		goto assign_new_owner;
		} while_each_thread(g, c);

		}
		read_unlock(&tasklist_lock);
		/*
		* We found no owner yet mm_users > 1: this implies that we are