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Commit ad962441 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

oom_kill: has_intersects_mems_allowed() needs rcu_read_lock() 



At least out_of_memory() calls has_intersects_mems_allowed() without
even rcu_read_lock(), this is obviously buggy.

Add the necessary rcu_read_lock().  This means that we can not simply
return from the loop, we need "bool ret" and "break".

While at it, swap the names of task_struct's (the argument and the
local).  This cleans up the code a little bit and avoids the unnecessary
initialization.

Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarSergey Dyasly <dserrg@gmail.com>
Tested-by: default avatarSergey Dyasly <dserrg@gmail.com>
Reviewed-by: default avatarSameer Nanda <snanda@chromium.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mandeep Singh Baines <msb@chromium.org>
Cc: "Ma, Xindong" <xindong.ma@intel.com>
Reviewed-by: default avatarMichal Hocko <mhocko@suse.cz>
Cc: "Tu, Xiaobing" <xiaobing.tu@intel.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 1da4db0c

mm/oom_kill.c

+11 −8
Original line number Diff line number Diff line
@@ -47,18 +47,20 @@ static DEFINE_SPINLOCK(zone_scan_lock); 
#ifdef CONFIG_NUMA

/**

 * has_intersects_mems_allowed() - check task eligiblity for kill

 * @tsk: task struct of which task to consider

 * @start: task struct of which task to consider

 * @mask: nodemask passed to page allocator for mempolicy ooms

 *

 * Task eligibility is determined by whether or not a candidate task, @tsk,

 * shares the same mempolicy nodes as current if it is bound by such a policy

 * and whether or not it has the same set of allowed cpuset nodes.

 */

static bool has_intersects_mems_allowed(struct task_struct *tsk,

static bool has_intersects_mems_allowed(struct task_struct *start,

					const nodemask_t *mask)

{

	struct task_struct *start = tsk;

	struct task_struct *tsk;

	bool ret = false;



	rcu_read_lock();

	for_each_thread(start, tsk) {

		if (mask) {

			/*
@@ -67,19 +69,20 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, 
			 * mempolicy intersects current, otherwise it may be

			 * needlessly killed.

			 */

			if (mempolicy_nodemask_intersects(tsk, mask))

				return true;

			ret = mempolicy_nodemask_intersects(tsk, mask);

		} else {

			/*

			 * This is not a mempolicy constrained oom, so only

			 * check the mems of tsk's cpuset.

			 */

			if (cpuset_mems_allowed_intersects(current, tsk))

				return true;

			ret = cpuset_mems_allowed_intersects(current, tsk);

		}

		if (ret)

			break;

	}

	rcu_read_unlock();



	return false;

	return ret;

}

#else

static bool has_intersects_mems_allowed(struct task_struct *tsk,