This is a note to let you know that I've just added the patch titled
io_uring: don't set COMP_LOCKED if won't put
to the 5.9-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-don-t-set-comp_locked-if-won-t-put.patch
and it can be found in the queue-5.9 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 6ad6d8e2917f309e12ba92f001536d2d05409d01
Author: Pavel Begunkov <asml.silence@xxxxxxxxx>
Date: Tue Oct 13 09:43:56 2020 +0100
io_uring: don't set COMP_LOCKED if won't put
[ Upstream commit 368c5481ae7c6a9719c40984faea35480d9f4872 ]
__io_kill_linked_timeout() sets REQ_F_COMP_LOCKED for a linked timeout
even if it can't cancel it, e.g. it's already running. It not only races
with io_link_timeout_fn() for ->flags field, but also leaves the flag
set and so io_link_timeout_fn() may find it and decide that it holds the
lock. Hopefully, the second problem is potential.
Signed-off-by: Pavel Begunkov <asml.silence@xxxxxxxxx>
Signed-off-by: Jens Axboe <axboe@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 59ab8c5c2aaaa..50a7a99dad4ca 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -1650,6 +1650,7 @@ static bool io_link_cancel_timeout(struct io_kiocb *req)
ret = hrtimer_try_to_cancel(&req->io->timeout.timer);
if (ret != -1) {
+ req->flags |= REQ_F_COMP_LOCKED;
io_cqring_fill_event(req, -ECANCELED);
io_commit_cqring(ctx);
req->flags &= ~REQ_F_LINK_HEAD;
@@ -1672,7 +1673,6 @@ static bool __io_kill_linked_timeout(struct io_kiocb *req)
return false;
list_del_init(&link->link_list);
- link->flags |= REQ_F_COMP_LOCKED;
wake_ev = io_link_cancel_timeout(link);
req->flags &= ~REQ_F_LINK_TIMEOUT;
return wake_ev;
