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oom_kill: has_intersects_mems_allowed() needs rcu_read_lock()

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commit ad96244179 upstream.

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: 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>
Cc: Li Zefan <lizefan@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Oleg Nesterov
2014-01-21 15:50:00 -08:00
committed by Greg Kroah-Hartman
parent 4940a48e7d
commit a214c050ee
1 changed files with 11 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

19
mm/oom_kill.c
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@@ -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,