From patchwork Thu Apr 14 13:11:39 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 561819 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 125DEC4332F for ; Thu, 14 Apr 2022 13:34:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244885AbiDNNg3 (ORCPT ); Thu, 14 Apr 2022 09:36:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49982 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343498AbiDNN3W (ORCPT ); Thu, 14 Apr 2022 09:29:22 -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 6B4EB95A3C; Thu, 14 Apr 2022 06:24:17 -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 1A597B82984; Thu, 14 Apr 2022 13:24:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 83744C385A5; Thu, 14 Apr 2022 13:24:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649942654; bh=8eD3NBqN/q0rqhEJ4PrIDbklKcrEr68iBunmR+/7aRM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gy1FJe8RokNYsGpEfZHKdSiX3s0lgkhQS+BKEkQk6kiKbqfEHg9uo8yc1vLeVcwHY 805cXOErTrWO4l2otdfv0Hdirug++G/5lNk+rMgoAYGUtokqjdqHhooohkFdaI09Te JovFTxNSkRUoeMTps33OUcyIZ0KVpAd68fnpDZNM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?utf-8?q?Holger_Hoffst=C3=A4tte?= , Paolo Valente , Jens Axboe , Sasha Levin Subject: [PATCH 4.19 196/338] Revert "Revert "block, bfq: honor already-setup queue merges"" Date: Thu, 14 Apr 2022 15:11:39 +0200 Message-Id: <20220414110844.475505816@linuxfoundation.org> X-Mailer: git-send-email 2.35.2 In-Reply-To: <20220414110838.883074566@linuxfoundation.org> References: <20220414110838.883074566@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@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 dfd55037dc6f..a9f42df92ea3 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2155,6 +2155,15 @@ 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; } @@ -2214,6 +2223,10 @@ 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; + /* * Prevent bfqq from being merged if it has been created too * long ago. The idea is that true cooperating processes, and @@ -2228,9 +2241,6 @@ 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;