UPSTREAM: io_uring: fix tw losing poll events

[ upstream commit 539bcb57 ]

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@vger.kernel.org
Fixes: aa43477b ("io_uring: poll rework")
Change-Id: I523ad04db17bdb27151e992083bbaaec1b6f851f
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/00344d60f8b18907171178d7cf598de71d127b0b.1668710222.git.asml.silence@gmail.com


Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit cd1981a8)
Bug: 268174392
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>