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Commit 1da4db0c authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
Browse files

oom_kill: change oom_kill.c to use for_each_thread() 



Change oom_kill.c to use for_each_thread() rather than the racy
while_each_thread() which can loop forever if we race with exit.

Note also that most users were buggy even if while_each_thread() was
fine, the task can exit even _before_ rcu_read_lock().

Fortunately the new for_each_thread() only requires the stable
task_struct, so this change fixes both problems.

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 0c740d0a

mm/oom_kill.c

+10 −10
Original line number Original line Diff line number Diff line
@@ -59,7 +59,7 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, 
{

{

	struct task_struct *start = tsk;

	struct task_struct *start = tsk;





	do {

	for_each_thread(start, tsk) {

		if (mask) {

		if (mask) {

			/*

			/*

			 * If this is a mempolicy constrained oom, tsk's

			 * If this is a mempolicy constrained oom, tsk's
@@ -77,7 +77,7 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, 
			if (cpuset_mems_allowed_intersects(current, tsk))

			if (cpuset_mems_allowed_intersects(current, tsk))

				return true;

				return true;

		}

		}

	} while_each_thread(start, tsk);

	}





	return false;

	return false;

}

}
@@ -97,14 +97,14 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, 
 */

 */

struct task_struct *find_lock_task_mm(struct task_struct *p)

struct task_struct *find_lock_task_mm(struct task_struct *p)

{

{

	struct task_struct *t = p;

	struct task_struct *t;





	do {

	for_each_thread(p, t) {

		task_lock(t);

		task_lock(t);

		if (likely(t->mm))

		if (likely(t->mm))

			return t;

			return t;

		task_unlock(t);

		task_unlock(t);

	} while_each_thread(p, t);

	}





	return NULL;

	return NULL;

}

}
@@ -301,7 +301,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, 
	unsigned long chosen_points = 0;

	unsigned long chosen_points = 0;





	rcu_read_lock();

	rcu_read_lock();

	do_each_thread(g, p) {

	for_each_process_thread(g, p) {

		unsigned int points;

		unsigned int points;





		switch (oom_scan_process_thread(p, totalpages, nodemask,

		switch (oom_scan_process_thread(p, totalpages, nodemask,
@@ -323,7 +323,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, 
			chosen = p;

			chosen = p;

			chosen_points = points;

			chosen_points = points;

		}

		}

	} while_each_thread(g, p);

	}

	if (chosen)

	if (chosen)

		get_task_struct(chosen);

		get_task_struct(chosen);

	rcu_read_unlock();

	rcu_read_unlock();
@@ -406,7 +406,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 
{

{

	struct task_struct *victim = p;

	struct task_struct *victim = p;

	struct task_struct *child;

	struct task_struct *child;

	struct task_struct *t = p;

	struct task_struct *t;

	struct mm_struct *mm;

	struct mm_struct *mm;

	unsigned int victim_points = 0;

	unsigned int victim_points = 0;

	static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,

	static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL,
@@ -437,7 +437,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 
	 * still freeing memory.

	 * still freeing memory.

	 */

	 */

	read_lock(&tasklist_lock);

	read_lock(&tasklist_lock);

	do {

	for_each_thread(p, t) {

		list_for_each_entry(child, &t->children, sibling) {

		list_for_each_entry(child, &t->children, sibling) {

			unsigned int child_points;

			unsigned int child_points;
@@ -455,7 +455,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 
				get_task_struct(victim);

				get_task_struct(victim);

			}

			}

		}

		}

	} while_each_thread(p, t);

	}

	read_unlock(&tasklist_lock);

	read_unlock(&tasklist_lock);





	rcu_read_lock();

	rcu_read_lock();