[PATCH mm] epoll: fix suspicious RCU usage in ep_poll_callback

[Eric Wong <normalperson@yhbt.net>]

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The commit "epoll: use RCU to protect wakeup_source in epitem"
introduced the ep_pm_stay_awake_rcu function for ep_poll_callback
use, but I left it unused on accident.  ep->mtx cannot be held in
ep_poll_callback, so RCU should be used here.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Oleg Nesterov <oleg@redhat.com>
---
  Oops :x

 fs/eventpoll.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index a4e4ad7..a81f0ea 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1028,7 +1028,7 @@ static int ep_poll_callback(wait_queue_t *wait, unsigned mode, int sync, void *k
 	/* If this file is already in the ready list we exit soon */
 	if (!ep_is_linked(&epi->rdllink)) {
 		list_add_tail(&epi->rdllink, &ep->rdllist);
-		ep_pm_stay_awake(epi);
+		ep_pm_stay_awake_rcu(epi);
 	}
 
 	/*
-- 
Eric Wong