From patchwork Mon Aug 16 13:01:38 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 498757 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham 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 1B1D0C43216 for ; Mon, 16 Aug 2021 13:16:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0846563321 for ; Mon, 16 Aug 2021 13:16:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239992AbhHPNQh (ORCPT ); Mon, 16 Aug 2021 09:16:37 -0400 Received: from mail.kernel.org ([198.145.29.99]:37186 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240299AbhHPNPE (ORCPT ); Mon, 16 Aug 2021 09:15:04 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 16AD3632D8; Mon, 16 Aug 2021 13:12:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1629119544; bh=wIIjKmFH0euQgXstQ8ky9Kw/RhFBEoQ27fKrn1QOueE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YfrAMFeVwXKMVE5m6vJVndS10oHi8RyRazeEhGuyVenrZtHb7g2a+Pi/nOcBlgghp qbqLPTmEGxiIufEOUTfykRPkp6ArZNKcpv9t6ibmeQebLdCeN/0puQDD4tcDBRTGK6 7OjXh08p0hkBnirrus0KxjcnRN0T0S6UsxCmd1+g= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jens Axboe , Pavel Begunkov , Nadav Amit , Sasha Levin Subject: [PATCH 5.13 068/151] io_uring: clear TIF_NOTIFY_SIGNAL when running task work Date: Mon, 16 Aug 2021 15:01:38 +0200 Message-Id: <20210816125446.308819084@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210816125444.082226187@linuxfoundation.org> References: <20210816125444.082226187@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nadav Amit [ Upstream commit ef98eb0409c31c39ab55ff46b2721c3b4f84c122 ] When using SQPOLL, the submission queue polling thread calls task_work_run() to run queued work. However, when work is added with TWA_SIGNAL - as done by io_uring itself - the TIF_NOTIFY_SIGNAL remains set afterwards and is never cleared. Consequently, when the submission queue polling thread checks whether signal_pending(), it may always find a pending signal, if task_work_add() was ever called before. The impact of this bug might be different on different kernel versions. It appears that on 5.14 it would only cause unnecessary calculation and prevent the polling thread from sleeping. On 5.13, where the bug was found, it stops the polling thread from finding newly submitted work. Instead of task_work_run(), use tracehook_notify_signal() that clears TIF_NOTIFY_SIGNAL. Test for TIF_NOTIFY_SIGNAL in addition to current->task_works to avoid a race in which task_works is cleared but the TIF_NOTIFY_SIGNAL is set. Fixes: 685fe7feedb96 ("io-wq: eliminate the need for a manager thread") Cc: Jens Axboe Cc: Pavel Begunkov Signed-off-by: Nadav Amit Link: https://lore.kernel.org/r/20210808001342.964634-2-namit@vmware.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- fs/io_uring.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 32f3df13a812..8a8507cab580 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -78,6 +78,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -2250,9 +2251,9 @@ static inline unsigned int io_put_rw_kbuf(struct io_kiocb *req) static inline bool io_run_task_work(void) { - if (current->task_works) { + if (test_thread_flag(TIF_NOTIFY_SIGNAL) || current->task_works) { __set_current_state(TASK_RUNNING); - task_work_run(); + tracehook_notify_signal(); return true; }