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mempolicy: remove tasklist_lock from migrate_pages

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Today, tasklist_lock in migrate_pages doesn't protect anything.
rcu_read_lock() provide enough protection from pid hash walk.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KOSAKI Motohiro 2011-01-13 15:46:14 -08:00 committed by Linus Torvalds
parent 53a7706d5e
commit 1e50df39f6
1 changed files with 0 additions and 3 deletions
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3
mm/mempolicy.c
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@ -1310,16 +1310,13 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode,
/* Find the mm_struct */
rcu_read_lock();
read_lock(&tasklist_lock);
task = pid ? find_task_by_vpid(pid) : current;
if (!task) {
read_unlock(&tasklist_lock);
rcu_read_unlock();
err = -ESRCH;
goto out;
}
mm = get_task_mm(task);
read_unlock(&tasklist_lock);
rcu_read_unlock();
err = -EINVAL;