From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39174C54EBE for ; Mon, 16 Jan 2023 16:07:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232116AbjAPQHZ (ORCPT ); Mon, 16 Jan 2023 11:07:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232064AbjAPQGq (ORCPT ); Mon, 16 Jan 2023 11:06:46 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 526BA26588 for ; Mon, 16 Jan 2023 08:05:03 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E3C7860C1B for ; Mon, 16 Jan 2023 16:05:02 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 025CFC433EF; Mon, 16 Jan 2023 16:05:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1673885102; bh=uu30+jzKJ531bnNqhlr7Q2wziYBZBi1edgJbw7q4IVQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RTPCX3trUoOjNB0EE1UurjRHTBuU90s0acSQNt8cXCVQzL4e60770LmLmE/m3hzRS RBOuUzJqCQNq7PXnDdosIQ/Ay3RgEbxBb23YCy3r4ui2qUR467l5IIhuKhGJui0Mzu NRiItsli3iEavocXngAi5vphuuJEM0RuKUsFpwFk= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pavel Begunkov , Jens Axboe , Sasha Levin , syzbot+6805087452d72929404e@syzkaller.appspotmail.com Subject: [PATCH 5.15 76/86] io_uring: lock overflowing for IOPOLL Date: Mon, 16 Jan 2023 16:51:50 +0100 Message-Id: <20230116154750.210435869@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230116154747.036911298@linuxfoundation.org> References: <20230116154747.036911298@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Pavel Begunkov commit 544d163d659d45a206d8929370d5a2984e546cb7 upstream. syzbot reports an issue with overflow filling for IOPOLL: WARNING: CPU: 0 PID: 28 at io_uring/io_uring.c:734 io_cqring_event_overflow+0x1c0/0x230 io_uring/io_uring.c:734 CPU: 0 PID: 28 Comm: kworker/u4:1 Not tainted 6.2.0-rc3-syzkaller-16369-g358a161a6a9e #0 Workqueue: events_unbound io_ring_exit_work Call trace:  io_cqring_event_overflow+0x1c0/0x230 io_uring/io_uring.c:734  io_req_cqe_overflow+0x5c/0x70 io_uring/io_uring.c:773  io_fill_cqe_req io_uring/io_uring.h:168 [inline]  io_do_iopoll+0x474/0x62c io_uring/rw.c:1065  io_iopoll_try_reap_events+0x6c/0x108 io_uring/io_uring.c:1513  io_uring_try_cancel_requests+0x13c/0x258 io_uring/io_uring.c:3056  io_ring_exit_work+0xec/0x390 io_uring/io_uring.c:2869  process_one_work+0x2d8/0x504 kernel/workqueue.c:2289  worker_thread+0x340/0x610 kernel/workqueue.c:2436  kthread+0x12c/0x158 kernel/kthread.c:376  ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:863 There is no real problem for normal IOPOLL as flush is also called with uring_lock taken, but it's getting more complicated for IOPOLL|SQPOLL, for which __io_cqring_overflow_flush() happens from the CQ waiting path. Reported-and-tested-by: syzbot+6805087452d72929404e@syzkaller.appspotmail.com Cc: stable@vger.kernel.org # 5.10+ Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- io_uring/io_uring.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index c587221a289c..9a01188ff45a 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -2477,12 +2477,26 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events, io_init_req_batch(&rb); while (!list_empty(done)) { + struct io_uring_cqe *cqe; + unsigned cflags; + req = list_first_entry(done, struct io_kiocb, inflight_entry); list_del(&req->inflight_entry); - - io_fill_cqe_req(req, req->result, io_put_rw_kbuf(req)); + cflags = io_put_rw_kbuf(req); (*nr_events)++; + cqe = io_get_cqe(ctx); + if (cqe) { + WRITE_ONCE(cqe->user_data, req->user_data); + WRITE_ONCE(cqe->res, req->result); + WRITE_ONCE(cqe->flags, cflags); + } else { + spin_lock(&ctx->completion_lock); + io_cqring_event_overflow(ctx, req->user_data, + req->result, cflags); + spin_unlock(&ctx->completion_lock); + } + if (req_ref_put_and_test(req)) io_req_free_batch(&rb, req, &ctx->submit_state); } -- 2.35.1