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 B35A8C433F5 for ; Tue, 5 Apr 2022 09:32:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238806AbiDEJcw (ORCPT ); Tue, 5 Apr 2022 05:32:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51456 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239718AbiDEIUf (ORCPT ); Tue, 5 Apr 2022 04:20:35 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7290E1C6; Tue, 5 Apr 2022 01:18:37 -0700 (PDT) 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 ams.source.kernel.org (Postfix) with ESMTPS id 225A0B81A32; Tue, 5 Apr 2022 08:18:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 89A98C385A0; Tue, 5 Apr 2022 08:18:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649146714; bh=tY0kWrVK2ImjRBv09UVGDLJkPT0jzUKnZ6CYAiVMoiE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jYELWuXmlpQ3nED/QNXjr90f/XR+BF52vkFkkAehTuUU+4EiP/VWvxcDGVfQ8Qqch R9ksdJbhlr0K2ZuPcistqI/mCfMqL+cBSDzshqyzBoa2SA2o94PUttyQ2DzmvgHG1s RInjIB4nLK9kGUMW470x1Y4XU7/Nl+4u712C4S0o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Holger=20Hoffst=C3=A4tte?= , Paolo Valente , Jens Axboe , Sasha Levin Subject: [PATCH 5.17 0862/1126] Revert "Revert "block, bfq: honor already-setup queue merges"" Date: Tue, 5 Apr 2022 09:26:49 +0200 Message-Id: <20220405070432.841496884@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070407.513532867@linuxfoundation.org> References: <20220405070407.513532867@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Paolo Valente [ Upstream commit 15729ff8143f8135b03988a100a19e66d7cb7ecd ] A crash [1] happened to be triggered in conjunction with commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges"). The latter was then reverted by commit ebc69e897e17 ("Revert "block, bfq: honor already-setup queue merges""). Yet, the reverted commit was not the one introducing the bug. In fact, it actually triggered a UAF introduced by a different commit, and now fixed by commit d29bd41428cf ("block, bfq: reset last_bfqq_created on group change"). So, there is no point in keeping commit 2d52c58b9c9b ("block, bfq: honor already-setup queue merges") out. This commit restores it. [1] https://bugzilla.kernel.org/show_bug.cgi?id=214503 Reported-by: Holger Hoffstätte Signed-off-by: Paolo Valente Link: https://lore.kernel.org/r/20211125181510.15004-1-paolo.valente@linaro.org Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/bfq-iosched.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 8735f075230f..1dff82d34b44 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2782,6 +2782,15 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) * are likely to increase the throughput. */ bfqq->new_bfqq = new_bfqq; + /* + * The above assignment schedules the following redirections: + * each time some I/O for bfqq arrives, the process that + * generated that I/O is disassociated from bfqq and + * associated with new_bfqq. Here we increases new_bfqq->ref + * in advance, adding the number of processes that are + * expected to be associated with new_bfqq as they happen to + * issue I/O. + */ new_bfqq->ref += process_refs; return new_bfqq; } @@ -2844,6 +2853,10 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, { struct bfq_queue *in_service_bfqq, *new_bfqq; + /* if a merge has already been setup, then proceed with that first */ + if (bfqq->new_bfqq) + return bfqq->new_bfqq; + /* * Check delayed stable merge for rotational or non-queueing * devs. For this branch to be executed, bfqq must not be @@ -2945,9 +2958,6 @@ bfq_setup_cooperator(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (bfq_too_late_for_merging(bfqq)) return NULL; - if (bfqq->new_bfqq) - return bfqq->new_bfqq; - if (!io_struct || unlikely(bfqq == &bfqd->oom_bfqq)) return NULL; -- 2.34.1