Messages in this thread | | | Subject | Re: rcu_read_lock/unlock protect find_task_by_vpid call in migrate_pages | From | Peter Zijlstra <> | Date | Thu, 25 Nov 2010 09:42:21 +0100 |
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On Thu, 2010-11-25 at 09:50 +0900, KOSAKI Motohiro wrote: > Hi > > > Signed-off-by: Dave Jones <davej@redhat.com> > > > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > > index 4a57f13..2f0f55b 100644 > > --- a/mm/mempolicy.c > > +++ b/mm/mempolicy.c > > @@ -1308,6 +1308,7 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, > > > > /* Find the mm_struct */ > > read_lock(&tasklist_lock); > > + rcu_read_lock(); > > task = pid ? find_task_by_vpid(pid) : current; > > if (!task) { > > read_unlock(&tasklist_lock); > > @@ -1315,6 +1316,7 @@ SYSCALL_DEFINE4(migrate_pages, pid_t, pid, unsigned long, maxnode, > > goto out; > > } > > mm = get_task_mm(task); > > + rcu_read_unlock(); > > read_unlock(&tasklist_lock); > > > > err = -EINVAL; > > Thanks reporting. but mmotm seems already has the same patch.
Another one,... again:
Do we still need the tasklist_lock in this case?
Also, why is that think complaining, surely the tasklist_lock pins any and all PID objects?
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