From patchwork Tue Nov 8 18:10:29 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Khazhy Kumykov X-Patchwork-Id: 13036646 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 54932C4332F for ; Tue, 8 Nov 2022 18:10:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234738AbiKHSKt (ORCPT ); Tue, 8 Nov 2022 13:10:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59098 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234733AbiKHSKs (ORCPT ); Tue, 8 Nov 2022 13:10:48 -0500 Received: from mail-pl1-x62e.google.com (mail-pl1-x62e.google.com [IPv6:2607:f8b0:4864:20::62e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2CCCA50F1D for ; Tue, 8 Nov 2022 10:10:44 -0800 (PST) Received: by mail-pl1-x62e.google.com with SMTP id u6so14855276plq.12 for ; Tue, 08 Nov 2022 10:10:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=eWhULAO1PGhpQ+ChwOYcLNZC3f58WMaAVvC3B9Ax33I=; b=OgzPo8mpGNo5exrre/OhRCO+v816mE1waYy6787p/nQN/NFFZsxn5irwVZFL5r59nK x7EWvXlhyznmWuDdfthA2yb4OyR11IASvIamkj1DwgqiZa+qLYaOJi2eEilaUrVEKzk8 BmUYdSjxJ+fmBVou4WlXk29qTxMPYZ11FG5aI= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=eWhULAO1PGhpQ+ChwOYcLNZC3f58WMaAVvC3B9Ax33I=; b=wAhgeFAozBLmHEgcGxnNEs1KmMOjxwdTcYlywA1Rf46NDgx9ttO/HMMllbJVA6JLar u8CbqvklueKNgmnj6btnuw1CIxOpcvml1Q93svpA+BhL11XWpl432xRvmXtflVeHJ2g2 h14XK39brCMHJerjzKhdxQwbhQMEG5ZIoYX4EqqRr2TxxChuN1BLPQpbnSbJt39l+SmF m+NU6Z+fRZfW9seunsSDZ3k36K7NKBIB57pBMbD4MDf9R8wQdQUGKThh0YV1crIUPC9i hHsQNYhUcCfP8CHwX2pVsOqOkZhwP0o4lWiZtRkvOQpLfMk41L9WdMP4bnxg/5Vd0P2Q kYYQ== X-Gm-Message-State: ACrzQf1eGAU1D/EjQtG/nvec6zyQVxpR9Ovpxd80UiEhMkmekSjz/X1v G3s97MdxyywPTzxevkT9hdjJfw== X-Google-Smtp-Source: AMsMyM5JdjlJDsuzUS3rfn2V0Wd1PJvEuFBmM2cCCPRZeXudLibia2TOoUKOYyUhYKZB+L6OntvxEg== X-Received: by 2002:a17:902:ecc1:b0:186:b57e:d229 with SMTP id a1-20020a170902ecc100b00186b57ed229mr58084545plh.167.1667931043637; Tue, 08 Nov 2022 10:10:43 -0800 (PST) Received: from khazhy-linux.svl.corp.google.com ([2620:15c:2d4:203:21f:525:beef:f928]) by smtp.gmail.com with ESMTPSA id h3-20020a63df43000000b0046fd180640asm6048754pgj.24.2022.11.08.10.10.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 08 Nov 2022 10:10:43 -0800 (PST) From: Khazhismel Kumykov X-Google-Original-From: Khazhismel Kumykov To: Paolo Valente , Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Yu Kuai , Jan Kara , Khazhismel Kumykov Subject: [PATCH 1/2] bfq: fix waker_bfqq inconsistency crash Date: Tue, 8 Nov 2022 10:10:29 -0800 Message-Id: <20221108181030.1611703-1-khazhy@google.com> X-Mailer: git-send-email 2.38.1.431.g37b22c650d-goog In-Reply-To: <20221103013937.603626-1-khazhy@google.com> References: <20221103013937.603626-1-khazhy@google.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This fixes crashes in bfq_add_bfqq_busy due to waker_bfqq being NULL, but woken_list_node still being hashed. This would happen when bfq_init_rq() expects a brand new allocated queue to be returned from bfq_get_bfqq_handle_split() and unconditionally updates waker_bfqq without resetting woken_list_node. Since we can always return oom_bfqq when attempting to allocate, we cannot assume waker_bfqq starts as NULL. Avoid setting woken_bfqq for oom_bfqq entirely, as it's not useful. Crashes would have a stacktrace like: [160595.656560] bfq_add_bfqq_busy+0x110/0x1ec [160595.661142] bfq_add_request+0x6bc/0x980 [160595.666602] bfq_insert_request+0x8ec/0x1240 [160595.671762] bfq_insert_requests+0x58/0x9c [160595.676420] blk_mq_sched_insert_request+0x11c/0x198 [160595.682107] blk_mq_submit_bio+0x270/0x62c [160595.686759] __submit_bio_noacct_mq+0xec/0x178 [160595.691926] submit_bio+0x120/0x184 [160595.695990] ext4_mpage_readpages+0x77c/0x7c8 [160595.701026] ext4_readpage+0x60/0xb0 [160595.705158] filemap_read_page+0x54/0x114 [160595.711961] filemap_fault+0x228/0x5f4 [160595.716272] do_read_fault+0xe0/0x1f0 [160595.720487] do_fault+0x40/0x1c8 Tested by injecting random failures into bfq_get_queue, crashes go away completely. Fixes: 8ef3fc3a043c ("block, bfq: make shared queues inherit wakers") Signed-off-by: Khazhismel Kumykov Reviewed-by: Jan Kara --- block/bfq-iosched.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 7ea427817f7f..ca04ec868c40 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -6784,6 +6784,12 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) bfqq = bfq_get_bfqq_handle_split(bfqd, bic, bio, true, is_sync, NULL); + if (unlikely(bfqq == &bfqd->oom_bfqq)) + bfqq_already_existing = true; + } else + bfqq_already_existing = true; + + if (!bfqq_already_existing) { bfqq->waker_bfqq = old_bfqq->waker_bfqq; bfqq->tentative_waker_bfqq = NULL; @@ -6797,8 +6803,7 @@ static struct bfq_queue *bfq_init_rq(struct request *rq) if (bfqq->waker_bfqq) hlist_add_head(&bfqq->woken_list_node, &bfqq->waker_bfqq->woken_list); - } else - bfqq_already_existing = true; + } } }