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oom_kill: change oom_kill.c to use for_each_thread()

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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: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Sergey Dyasly <dserrg@gmail.com>
Tested-by: Sergey Dyasly <dserrg@gmail.com>
Reviewed-by: Sameer 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: Michal Hocko <mhocko@suse.cz>
Cc: "Tu, Xiaobing" <xiaobing.tu@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Oleg Nesterov 2014-01-21 15:49:58 -08:00 committed by Linus Torvalds
parent 0c740d0afc
commit 1da4db0cd5
1 changed files with 10 additions and 10 deletions
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20
mm/oom_kill.c
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@ -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();