This is a note to let you know that I've just added the patch titled
io_uring: remove poll entry from list when canceling all
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-remove-poll-entry-from-list-when-canceling-all.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 Thu Sep 1 11:59:31 AM CEST 2022
From: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Mon, 29 Aug 2022 14:30:20 +0100
Subject: io_uring: remove poll entry from list when canceling all
To: stable@xxxxxxxxxxxxxxx
Cc: Jens Axboe <axboe@xxxxxxxxx>, asml.silence@xxxxxxxxx, Dylan Yudaken <dylany@xxxxxx>
Message-ID: <83da9963edf6789d744c4e6db4a3943e58ce8c0b.1661594698.git.asml.silence@xxxxxxxxx>
From: Jens Axboe <axboe@xxxxxxxxx>
[ upstream commmit 61bc84c4008812d784c398cfb54118c1ba396dfc ]
When the ring is exiting, as part of the shutdown, poll requests are
removed. But io_poll_remove_all() does not remove entries when finding
them, and since completions are done out-of-band, we can find and remove
the same entry multiple times.
We do guard the poll execution by poll ownership, but that does not
exclude us from reissuing a new one once the previous removal ownership
goes away.
This can race with poll execution as well, where we then end up seeing
req->apoll be NULL because a previous task_work requeue finished the
request.
Remove the poll entry when we find it and get ownership of it. This
prevents multiple invocations from finding it.
Fixes: aa43477b0402 ("io_uring: poll rework")
Reported-by: Dylan Yudaken <dylany@xxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
[pavel: backport]
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/io_uring.c | 1 +
1 file changed, 1 insertion(+)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -5720,6 +5720,7 @@ static bool io_poll_remove_all(struct io
list = &ctx->cancel_hash[i];
hlist_for_each_entry_safe(req, tmp, list, hash_node) {
if (io_match_task_safe(req, tsk, cancel_all)) {
+ hlist_del_init(&req->hash_node);
io_poll_cancel_req(req);
found = true;
}
Patches currently in stable-queue which might be from asml.silence@xxxxxxxxx are
queue-5.15/io_uring-fix-wrong-arm_poll-error-handling.patch
queue-5.15/io_uring-poll-rework.patch
queue-5.15/io_uring-remove-unused-function-req_ref_put.patch
queue-5.15/io_uring-fail-links-when-poll-fails.patch
queue-5.15/io_uring-inline-io_poll_complete.patch
queue-5.15/io_uring-bump-poll-refs-to-full-31-bits.patch
queue-5.15/io_uring-clean-cqe-filling-functions.patch
queue-5.15/io_uring-fix-uaf-due-to-missing-pollfree-handling.patch
queue-5.15/io_uring-correct-fill-events-helpers-types.patch
queue-5.15/io_uring-refactor-poll-update.patch
queue-5.15/io_uring-kill-poll-linking-optimisation.patch
queue-5.15/io_uring-remove-poll-entry-from-list-when-canceling-all.patch
queue-5.15/io_uring-move-common-poll-bits.patch
