From patchwork Mon Aug 10 15:20:55 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 266614 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C2C88C433E0 for ; Mon, 10 Aug 2020 15:40:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9428320825 for ; Mon, 10 Aug 2020 15:40:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597074051; bh=YPDX0crp7GERTlrl95GtvjvBnhsR8R4/6rjI44AeOc0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ydFS7TUpD6ivCnnXMRJ/qAcU5bEyynkuUDnDgYPfqSFsB+Zzalo7/hxoIkduxLzOP qrR0KKumvsAt7JxsW7g90huk2EMSwHgJ3SOgyGViEIfJ9PcJ+p0iZmUvsuaaq5uFUJ KG0p/foE2QIbwpLeyvxAPHrLmTeLhADK93TRoVfc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727982AbgHJPX5 (ORCPT ); Mon, 10 Aug 2020 11:23:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:56198 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728392AbgHJPXy (ORCPT ); Mon, 10 Aug 2020 11:23:54 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BCD8020782; Mon, 10 Aug 2020 15:23:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1597073034; bh=YPDX0crp7GERTlrl95GtvjvBnhsR8R4/6rjI44AeOc0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WgF4qe7ZetUpdcCbeISChIHyzaWi2EcWPbBUtLCwY7qSXNHqE2RRFDomjOGCYbEcl hZ/LQlPce91Us8SR/T30Bvvtm2ogPo1pisE+5ORnzpy9ZIT6e7sy6n/vSXEDkvzrHZ C6P3dG3/mLJLKs86x0kQ1HzzTjc53uoLsrvwUphI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pavel Begunkov , Jens Axboe , Sasha Levin Subject: [PATCH 5.7 36/79] io_uring: fix lockup in io_fail_links() Date: Mon, 10 Aug 2020 17:20:55 +0200 Message-Id: <20200810151814.064738321@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200810151812.114485777@linuxfoundation.org> References: <20200810151812.114485777@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Pavel Begunkov [ Upstream commit 4ae6dbd683860b9edc254ea8acf5e04b5ae242e5 ] io_fail_links() doesn't consider REQ_F_COMP_LOCKED leading to nested spin_lock(completion_lock) and lockup. [ 197.680409] rcu: INFO: rcu_preempt detected expedited stalls on CPUs/tasks: { 6-... } 18239 jiffies s: 1421 root: 0x40/. [ 197.680411] rcu: blocking rcu_node structures: [ 197.680412] Task dump for CPU 6: [ 197.680413] link-timeout R running task 0 1669 1 0x8000008a [ 197.680414] Call Trace: [ 197.680420] ? io_req_find_next+0xa0/0x200 [ 197.680422] ? io_put_req_find_next+0x2a/0x50 [ 197.680423] ? io_poll_task_func+0xcf/0x140 [ 197.680425] ? task_work_run+0x67/0xa0 [ 197.680426] ? do_exit+0x35d/0xb70 [ 197.680429] ? syscall_trace_enter+0x187/0x2c0 [ 197.680430] ? do_group_exit+0x43/0xa0 [ 197.680448] ? __x64_sys_exit_group+0x18/0x20 [ 197.680450] ? do_syscall_64+0x52/0xa0 [ 197.680452] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 4e09af1d5d223..fb9dc865c9eaa 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4260,10 +4260,9 @@ static void io_poll_task_handler(struct io_kiocb *req, struct io_kiocb **nxt) hash_del(&req->hash_node); io_poll_complete(req, req->result, 0); - req->flags |= REQ_F_COMP_LOCKED; - io_put_req_find_next(req, nxt); spin_unlock_irq(&ctx->completion_lock); + io_put_req_find_next(req, nxt); io_cqring_ev_posted(ctx); }