This is a note to let you know that I've just added the patch titled
epoll: ep_autoremove_wake_function should use list_del_init_careful
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
epoll-ep_autoremove_wake_function-should-use-list_de.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit dfb0850769b96ff66a480cf0d2982de5fd5d9122
Author: Benjamin Segall <bsegall@xxxxxxxxxx>
Date: Tue May 30 11:32:28 2023 -0700
epoll: ep_autoremove_wake_function should use list_del_init_careful
[ Upstream commit 2192bba03d80f829233bfa34506b428f71e531e7 ]
autoremove_wake_function uses list_del_init_careful, so should epoll's
more aggressive variant. It only doesn't because it was copied from an
older wait.c rather than the most recent.
[bsegall@xxxxxxxxxx: add comment]
Link: https://lkml.kernel.org/r/xm26bki0ulsr.fsf_-_@xxxxxxxxxx
Link: https://lkml.kernel.org/r/xm26pm6hvfer.fsf@xxxxxxxxxx
Fixes: a16ceb139610 ("epoll: autoremove wakers even more aggressively")
Signed-off-by: Ben Segall <bsegall@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Christian Brauner <brauner@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 877f9f61a4e8d..8c0e94183186f 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1814,7 +1814,11 @@ static int ep_autoremove_wake_function(struct wait_queue_entry *wq_entry,
{
int ret = default_wake_function(wq_entry, mode, sync, key);
- list_del_init(&wq_entry->entry);
+ /*
+ * Pairs with list_empty_careful in ep_poll, and ensures future loop
+ * iterations see the cause of this wakeup.
+ */
+ list_del_init_careful(&wq_entry->entry);
return ret;
}
