From patchwork Wed Mar 30 12:42:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Kara X-Patchwork-Id: 12795785 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 047B8C433EF for ; Wed, 30 Mar 2022 12:47:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241881AbiC3MtN (ORCPT ); Wed, 30 Mar 2022 08:49:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34400 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345436AbiC3Mqy (ORCPT ); Wed, 30 Mar 2022 08:46:54 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 980B77DE18; Wed, 30 Mar 2022 05:43:02 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 32D311F7AD; Wed, 30 Mar 2022 12:43:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1648644181; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=t33HL+ZUEFlbU34WO0KCc7WMDxCOogLnEO2lgYt7GyI=; b=tPra7vJ/PLkZjLoyJyJtYoj60GHLORHRUm26M/lmRqA7bZunT1JZDwpKQfeAz+pBHyRfwM TysElPdleLJn+lH0oQcRnEpnasA4mH5PxFj/ecNnbdu86K3OGzqFeeXAmGoFe2ZABANdvq CqQO/U3cQBP5FYGShhkrHj7GpWKUtME= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1648644181; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=t33HL+ZUEFlbU34WO0KCc7WMDxCOogLnEO2lgYt7GyI=; b=nOd1pPT6XfPDMMyWbG1wD1lHIGcuMJEOipfq0GGkICTFCaMTzS2NEw1ZgHHTzRxNGxHpTe CLOqcoEqNYhf/hAw== Received: from quack3.suse.cz (unknown [10.163.28.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 19C7FA3B87; Wed, 30 Mar 2022 12:43:01 +0000 (UTC) Received: by quack3.suse.cz (Postfix, from userid 1000) id 6D76CA0618; Wed, 30 Mar 2022 14:42:56 +0200 (CEST) From: Jan Kara To: Cc: Paolo Valente , Jens Axboe , "yukuai (C)" , Jan Kara , stable@vger.kernel.org Subject: [PATCH 2/9] bfq: Avoid merging queues with different parents Date: Wed, 30 Mar 2022 14:42:45 +0200 Message-Id: <20220330124255.24581-2-jack@suse.cz> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220330123438.32719-1-jack@suse.cz> References: <20220330123438.32719-1-jack@suse.cz> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2888; h=from:subject; bh=YqBlQaGG2lClN376Ajy30o6ZjdZ8iHsmFLLyoJCVJMo=; b=owEBbQGS/pANAwAIAZydqgc/ZEDZAcsmYgBiRFBFfmNBeD3h5JnQFvzsn+bZ+enOfvA9fnQFJLLh 6qs1mlWJATMEAAEIAB0WIQSrWdEr1p4yirVVKBycnaoHP2RA2QUCYkRQRQAKCRCcnaoHP2RA2SNqCA DLTF+x5XZWnpGNEd85aBZ7N00LIP8HRX74AP2CYrngUXsmkSErYh/j8UOjn9V0jivuHPQDSyt7/pvg 1JxCle30Fy0AGnFU28aadcquqQ8ZiEUoKN/uBLuVvsV9WDM6toKq83EEWr7cc7BVGPxb757Z7j4JVb DK2T1WktV+wMN46dg9g7f+7u+oipSegsHp3FzGErkc11KgXB4wRNopS2gzs7i4HGmKdLsk8EOat0qv FBBRHjA1SuUGeV2XcAPXI5i/fy7NiS/+FDB1UjIneZ908+cAetJKk2Nf7n9oKsh66f+YOyHybrbRBg lV+6MCfLXQ4ariBmU7NfJqaBSo0Kxx X-Developer-Key: i=jack@suse.cz; a=openpgp; fpr=93C6099A142276A28BBE35D815BC833443038D8C Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org It can happen that the parent of a bfqq changes between the moment we decide two queues are worth to merge (and set bic->stable_merge_bfqq) and the moment bfq_setup_merge() is called. This can happen e.g. because the process submitted IO for a different cgroup and thus bfqq got reparented. It can even happen that the bfqq we are merging with has parent cgroup that is already offline and going to be destroyed in which case the merge can lead to use-after-free issues such as: BUG: KASAN: use-after-free in __bfq_deactivate_entity+0x9cb/0xa50 Read of size 8 at addr ffff88800693c0c0 by task runc:[2:INIT]/10544 CPU: 0 PID: 10544 Comm: runc:[2:INIT] Tainted: G E 5.15.2-0.g5fb85fd-default #1 openSUSE Tumbleweed (unreleased) f1f3b891c72369aebecd2e43e4641a6358867c70 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 Call Trace: dump_stack_lvl+0x46/0x5a print_address_description.constprop.0+0x1f/0x140 ? __bfq_deactivate_entity+0x9cb/0xa50 kasan_report.cold+0x7f/0x11b ? __bfq_deactivate_entity+0x9cb/0xa50 __bfq_deactivate_entity+0x9cb/0xa50 ? update_curr+0x32f/0x5d0 bfq_deactivate_entity+0xa0/0x1d0 bfq_del_bfqq_busy+0x28a/0x420 ? resched_curr+0x116/0x1d0 ? bfq_requeue_bfqq+0x70/0x70 ? check_preempt_wakeup+0x52b/0xbc0 __bfq_bfqq_expire+0x1a2/0x270 bfq_bfqq_expire+0xd16/0x2160 ? try_to_wake_up+0x4ee/0x1260 ? bfq_end_wr_async_queues+0xe0/0xe0 ? _raw_write_unlock_bh+0x60/0x60 ? _raw_spin_lock_irq+0x81/0xe0 bfq_idle_slice_timer+0x109/0x280 ? bfq_dispatch_request+0x4870/0x4870 __hrtimer_run_queues+0x37d/0x700 ? enqueue_hrtimer+0x1b0/0x1b0 ? kvm_clock_get_cycles+0xd/0x10 ? ktime_get_update_offsets_now+0x6f/0x280 hrtimer_interrupt+0x2c8/0x740 Fix the problem by checking that the parent of the two bfqqs we are merging in bfq_setup_merge() is the same. Link: https://lore.kernel.org/linux-block/20211125172809.GC19572@quack2.suse.cz/ CC: stable@vger.kernel.org Fixes: 430a67f9d616 ("block, bfq: merge bursts of newly-created queues") Signed-off-by: Jan Kara --- block/bfq-iosched.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/block/bfq-iosched.c b/block/bfq-iosched.c index 6d122c28086e..7d00b21ebe5d 100644 --- a/block/bfq-iosched.c +++ b/block/bfq-iosched.c @@ -2758,6 +2758,14 @@ bfq_setup_merge(struct bfq_queue *bfqq, struct bfq_queue *new_bfqq) if (process_refs == 0 || new_process_refs == 0) return NULL; + /* + * Make sure merged queues belong to the same parent. Parents could + * have changed since the time we decided the two queues are suitable + * for merging. + */ + if (new_bfqq->entity.parent != bfqq->entity.parent) + return NULL; + bfq_log_bfqq(bfqq->bfqd, bfqq, "scheduling merge with queue %d", new_bfqq->pid);