This is a note to let you know that I've just added the patch titled
io_uring: fix tw losing poll events
to the 5.15-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:
io_uring-fix-tw-losing-poll-events.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Sat Dec 3 02:18:58 PM CET 2022
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Fri, 2 Dec 2022 14:27:12 +0000
Subject: io_uring: fix tw losing poll events
To: stable@xxxxxxxxxxxxxxx
Cc: Jens Axboe <axboe@xxxxxxxxx>, asml.silence@xxxxxxxxx
Message-ID: <f802e6ca1e75aca0d42a4febe8088527d9b3bd93.1669990799.git.asml.silence@xxxxxxxxx>
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
[ upstream commit 539bcb57da2f58886d7d5c17134236b0ec9cd15d ]
We may never try to process a poll wake and its mask if there was
multiple wake ups racing for queueing up a tw. Force
io_poll_check_events() to update the mask by vfs_poll().
Cc: stable@xxxxxxxxxxxxxxx
Fixes: aa43477b04025 ("io_uring: poll rework")
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Link: https://lore.kernel.org/r/00344d60f8b18907171178d7cf598de71d127b0b.1668710222.git.asml.silence@xxxxxxxxx
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5440,6 +5440,13 @@ static int io_poll_check_events(struct i
return 0;
if (v & IO_POLL_CANCEL_FLAG)
return -ECANCELED;
+ /*
+ * cqe.res contains only events of the first wake up
+ * and all others are be lost. Redo vfs_poll() to get
+ * up to date state.
+ */
+ if ((v & IO_POLL_REF_MASK) != 1)
+ req->result = 0;
if (!req->result) {
struct poll_table_struct pt = { ._key = poll->events };
Patches currently in stable-queue which might be from asml.silence@xxxxxxxxx are
queue-5.15/io_uring-fix-tw-losing-poll-events.patch
queue-5.15/io_uring-make-poll-refs-more-robust.patch
queue-5.15/io_uring-cmpxchg-for-poll-arm-refs-release.patch
queue-5.15/io_uring-poll-fix-poll_refs-race-with-cancelation.patch
queue-5.15/io_uring-update-res-mask-in-io_poll_check_events.patch
