From patchwork Sat Mar 21 09:45:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Valente X-Patchwork-Id: 11450811 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id A5DBD14B4 for ; Sat, 21 Mar 2020 09:45:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 835C92076F for ; Sat, 21 Mar 2020 09:45:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="g0wF+ou+" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728376AbgCUJpQ (ORCPT ); Sat, 21 Mar 2020 05:45:16 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:46975 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728238AbgCUJpP (ORCPT ); Sat, 21 Mar 2020 05:45:15 -0400 Received: by mail-wr1-f65.google.com with SMTP id j17so6896121wru.13 for ; Sat, 21 Mar 2020 02:45:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=3aRXmKaWpCikyhPB1r1OmE2K1u3/BRFi1kHB95qxuFw=; b=g0wF+ou+Z581+cBmPEU9Ede5RC7dNifbbFNqvzLutBgtLAn120kUaMH0t4rxT+JlH4 Mn5DNctfVE8t7kUofJeoSEOlHwMPXgyE/bb36JYczb2ot/a5MmIk1EYpkCa7wHjaHmYF DutIkIG2KE7GqcdZfou7rHwDDJouipWqQP4BNLdoA17IK5NxsFaudtxDUgXdfaNnVzUD OLRV6jOj9B6USC7AWKqnBQQDwoL+bTGXklYXJkqC8JVh/0+NDTjXpvSotK4Z02cqIqhE FDm8fEyv1A0lnRbI/pSBaUlLnd+iyciDalVskfkqUK2I2WK95UIwAw3hXJ1lcIdQzSuM OV4w== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=3aRXmKaWpCikyhPB1r1OmE2K1u3/BRFi1kHB95qxuFw=; b=GfLf5TJzlnt2XM5B4Z1pYpEcL0dMtvKUdPPECzx7FUBAJ2sdU5r834HV2xjMePoGkl aUCF9N29fbV+HT+I3TJh6SOTNocP1rYkjv0jDHkA/lqTEcPGuxboArrMDsTsMIF1L/de UsU/RDvllmnykkP2kV7LtK6/vF7FbZ0V2tec7rK7G2NgTsTnbBxLt/CX3ywI0Unxqkzb NCGzoJWAtxVhmvT7Eoua8D476TfbIrz4Ax7/COgtq4tszrlWAWgAYCLZjgXZ9BwkQY8k +jlSUoPEMJ/fHyYup6RrJbTw0zDj2px4BtRfKxQryAmj4UQRIYKWGhMzVOq8bZwQ4zTs xDIA== X-Gm-Message-State: ANhLgQ3hodm663y+6V+Cqc+ckk8+slZk+X9UnnPTpb5RFXT6jeG/g640 tWQnggBUcq/iXau3X8LwZC40dw== X-Google-Smtp-Source: ADFU+vt6T6nUeI6bl3t9eRMr9wGqBkGoytGMG7fogvZ6K4Vx2wN+9uT8zFhopeIu3DiGK0gsaJu5Nw== X-Received: by 2002:a5d:5106:: with SMTP id s6mr15497200wrt.24.1584783913506; Sat, 21 Mar 2020 02:45:13 -0700 (PDT) Received: from localhost.localdomain ([84.33.129.193]) by smtp.gmail.com with ESMTPSA id z203sm5396378wmg.12.2020.03.21.02.45.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 21 Mar 2020 02:45:12 -0700 (PDT) From: Paolo Valente To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, bfq-iosched@googlegroups.com, oleksandr@natalenko.name, rasibley@redhat.com, vkabatov@redhat.com, xzhou@redhat.com, jstancek@redhat.com, Paolo Valente , cki-project@redhat.com Subject: [PATCH BUGFIX 1/4] block, bfq: move forward the getting of an extra ref in bfq_bfqq_move Date: Sat, 21 Mar 2020 10:45:18 +0100 Message-Id: <20200321094521.85986-2-paolo.valente@linaro.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200321094521.85986-1-paolo.valente@linaro.org> References: <20200321094521.85986-1-paolo.valente@linaro.org> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Commit ecedd3d7e199 ("block, bfq: get extra ref to prevent a queue from being freed during a group move") gets an extra reference to a bfq_queue before possibly deactivating it (temporarily), in bfq_bfqq_move(). This prevents the bfq_queue from disappearing before being reactivated in its new group. Yet, the bfq_queue may also be expired (i.e., its service may be stopped) before the bfq_queue is deactivated. And also an expiration may lead to a premature freeing. This commit fixes this issue by simply moving forward the getting of the extra reference already introduced by commit ecedd3d7e199 ("block, bfq: get extra ref to prevent a queue from being freed during a group move"). Reported-by: cki-project@redhat.com Tested-by: cki-project@redhat.com Signed-off-by: Paolo Valente --- block/bfq-cgroup.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index f0ff6654af28..9d963ed518d1 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -642,6 +642,12 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, { struct bfq_entity *entity = &bfqq->entity; + /* + * Get extra reference to prevent bfqq from being freed in + * next possible expire or deactivate. + */ + bfqq->ref++; + /* If bfqq is empty, then bfq_bfqq_expire also invokes * bfq_del_bfqq_busy, thereby removing bfqq and its entity * from data structures related to current group. Otherwise we @@ -652,12 +658,6 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, bfq_bfqq_expire(bfqd, bfqd->in_service_queue, false, BFQQE_PREEMPTED); - /* - * get extra reference to prevent bfqq from being freed in - * next possible deactivate - */ - bfqq->ref++; - if (bfq_bfqq_busy(bfqq)) bfq_deactivate_bfqq(bfqd, bfqq, false, false); else if (entity->on_st_or_in_serv) @@ -677,7 +677,7 @@ void bfq_bfqq_move(struct bfq_data *bfqd, struct bfq_queue *bfqq, if (!bfqd->in_service_queue && !bfqd->rq_in_driver) bfq_schedule_dispatch(bfqd); - /* release extra ref taken above */ + /* release extra ref taken above, bfqq may happen to be freed now */ bfq_put_queue(bfqq); }