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authorPavel Begunkov <asml.silence@gmail.com>2021-05-23 15:48:39 +0100
committerJens Axboe <axboe@kernel.dk>2021-05-25 19:39:58 -0600
commit17a91051fe63b40ec651b80097c9fff5b093fdc5 (patch)
tree2ff23057d8bb5cbbed0b123eb9a8b3dd803c1586 /fs/io_uring.c
parentba5ef6dc8a827a904794210a227cdb94828e8ae7 (diff)
downloadlinux-17a91051fe63b40ec651b80097c9fff5b093fdc5.tar.bz2
io_uring/io-wq: close io-wq full-stop gap
There is an old problem with io-wq cancellation where requests should be killed and are in io-wq but are not discoverable, e.g. in @next_hashed or @linked vars of io_worker_handle_work(). It adds some unreliability to individual request canellation, but also may potentially get __io_uring_cancel() stuck. For instance: 1) An __io_uring_cancel()'s cancellation round have not found any request but there are some as desribed. 2) __io_uring_cancel() goes to sleep 3) Then workers wake up and try to execute those hidden requests that happen to be unbound. As we already cancel all requests of io-wq there, set IO_WQ_BIT_EXIT in advance, so preventing 3) from executing unbound requests. The workers will initially break looping because of getting a signal as they are threads of the dying/exec()'ing user task. Cc: stable@vger.kernel.org Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Link: https://lore.kernel.org/r/abfcf8c54cb9e8f7bfbad7e9a0cc5433cc70bdc2.1621781238.git.asml.silence@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'fs/io_uring.c')
-rw-r--r--fs/io_uring.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5f82954004f6..6af8ca0cb01c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9078,6 +9078,9 @@ static void io_uring_cancel_sqpoll(struct io_sq_data *sqd)
if (!current->io_uring)
return;
+ if (tctx->io_wq)
+ io_wq_exit_start(tctx->io_wq);
+
WARN_ON_ONCE(!sqd || sqd->thread != current);
atomic_inc(&tctx->in_idle);
@@ -9112,6 +9115,9 @@ void __io_uring_cancel(struct files_struct *files)
DEFINE_WAIT(wait);
s64 inflight;
+ if (tctx->io_wq)
+ io_wq_exit_start(tctx->io_wq);
+
/* make sure overflow events are dropped */
atomic_inc(&tctx->in_idle);
do {