This is a note to let you know that I've just added the patch titled io_uring: fix cancel of deferred reqs with ->files to the 5.8-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-cancel-of-deferred-reqs-with-files.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit dccc1613d34c85c432bb33580cf5f97242eb6ac2 Author: Pavel Begunkov <asml.silence@xxxxxxxxx> Date: Sun Sep 6 00:45:14 2020 +0300 io_uring: fix cancel of deferred reqs with ->files [ Upstream commit b7ddce3cbf010edbfac6c6d8cc708560a7bcd7a4 ] While trying to cancel requests with ->files, it also should look for requests in ->defer_list, otherwise it might end up hanging a thread. Cancel all requests in ->defer_list up to the last request there with matching ->files, that's needed to follow drain ordering semantics. 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 38f3ec15ba3b1..5f627194d0920 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -7675,12 +7675,38 @@ static void io_attempt_cancel(struct io_ring_ctx *ctx, struct io_kiocb *req) io_timeout_remove_link(ctx, req); } +static void io_cancel_defer_files(struct io_ring_ctx *ctx, + struct files_struct *files) +{ + struct io_kiocb *req = NULL; + LIST_HEAD(list); + + spin_lock_irq(&ctx->completion_lock); + list_for_each_entry_reverse(req, &ctx->defer_list, list) { + if ((req->flags & REQ_F_WORK_INITIALIZED) + && req->work.files == files) { + list_cut_position(&list, &ctx->defer_list, &req->list); + break; + } + } + spin_unlock_irq(&ctx->completion_lock); + + while (!list_empty(&list)) { + req = list_first_entry(&list, struct io_kiocb, list); + list_del_init(&req->list); + req_set_fail_links(req); + io_cqring_add_event(req, -ECANCELED); + io_double_put_req(req); + } +} + static void io_uring_cancel_files(struct io_ring_ctx *ctx, struct files_struct *files) { if (list_empty_careful(&ctx->inflight_list)) return; + io_cancel_defer_files(ctx, files); /* cancel all at once, should be faster than doing it one by one*/ io_wq_cancel_cb(ctx->io_wq, io_wq_files_match, files, true);