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 6.0-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-6.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 539bcb57da2f58886d7d5c17134236b0ec9cd15d Mon Sep 17 00:00:00 2001
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Thu, 17 Nov 2022 18:40:15 +0000
Subject: io_uring: fix tw losing poll events
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
commit 539bcb57da2f58886d7d5c17134236b0ec9cd15d upstream.
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>
---
io_uring/poll.c | 7 +++++++
1 file changed, 7 insertions(+)
--- a/io_uring/poll.c
+++ b/io_uring/poll.c
@@ -226,6 +226,13 @@ static int io_poll_check_events(struct i
return IOU_POLL_DONE;
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->cqe.res = 0;
/* the mask was stashed in __io_poll_execute */
if (!req->cqe.res) {
Patches currently in stable-queue which might be from asml.silence@xxxxxxxxx are
queue-6.0/io_uring-update-res-mask-in-io_poll_check_events.patch
queue-6.0/io_uring-fix-multishot-recv-request-leaks.patch
queue-6.0/io_uring-fix-tw-losing-poll-events.patch
queue-6.0/io_uring-fix-multishot-accept-request-leaks.patch
queue-6.0/io_uring-poll-fix-double-poll-req-flags-races.patch
queue-6.0/io_uring-disallow-self-propelled-ring-polling.patch
