FAILED: patch "[PATCH] epoll: ep_autoremove_wake_function should use" failed to apply to 5.4-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y
git checkout FETCH_HEAD
git cherry-pick -x 2192bba03d80f829233bfa34506b428f71e531e7
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023061737-smartness-mummify-9865@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2192bba03d80f829233bfa34506b428f71e531e7 Mon Sep 17 00:00:00 2001
From: Benjamin Segall <bsegall@google.com>
Date: Tue, 30 May 2023 11:32:28 -0700
Subject: [PATCH] epoll: ep_autoremove_wake_function should use
 list_del_init_careful

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@google.com: add comment]
  Link: https://lkml.kernel.org/r/xm26bki0ulsr.fsf_-_@google.com
Link: https://lkml.kernel.org/r/xm26pm6hvfer.fsf@google.com
Fixes: a16ceb139610 ("epoll: autoremove wakers even more aggressively")
Signed-off-by: Ben Segall <bsegall@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 980483455cc0..266d45c7685b 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -1805,7 +1805,11 @@ 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;
 }