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 81004C433F5 for ; Fri, 1 Apr 2022 10:28:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S245580AbiDAK3t (ORCPT ); Fri, 1 Apr 2022 06:29:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245560AbiDAK3p (ORCPT ); Fri, 1 Apr 2022 06:29:45 -0400 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5E1C526E54C; Fri, 1 Apr 2022 03:27:55 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id C53F01FCFF; Fri, 1 Apr 2022 10:27:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1648808873; 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=gfxNY8pkD4wG9bo/byknp9EmBiK4BnZ+HIjHLRJmYLM=; b=OYDInG951v/Tn30EwmyxCwQRTkzdj4fVyrjoLBkVB76VU4DZF9pI5NaKlQGjkCxXX9/TFs 0+QAH5RD2O7D6UnJP6jetX0v3nsL+4PtFe8bsiRwBLw1xtBQ24SoJy0lFrDKQp01RIsMCj JieM1Fs3tqwGdZzLPXuWdqnGdOmYZO8= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1648808873; 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=gfxNY8pkD4wG9bo/byknp9EmBiK4BnZ+HIjHLRJmYLM=; b=TdKHCYWkmP88CgSXAG2i3wBJ6Utm5z+jXSFCdBu+uZyjK/aYeOExocq9argQt338vqi4Gt qPlAZVoOyuWEbmDg== 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 A4262A3B89; Fri, 1 Apr 2022 10:27:53 +0000 (UTC) Received: by quack3.suse.cz (Postfix, from userid 1000) id 7C797A0618; Fri, 1 Apr 2022 12:27:52 +0200 (CEST) From: Jan Kara To: Paolo Valente Cc: , Jens Axboe , "yukuai (C)" , Jan Kara , stable@vger.kernel.org Subject: [PATCH 2/9] bfq: Avoid merging queues with different parents Date: Fri, 1 Apr 2022 12:27:43 +0200 Message-Id: <20220401102752.8599-2-jack@suse.cz> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220401102325.17617-1-jack@suse.cz> References: <20220401102325.17617-1-jack@suse.cz> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2934; h=from:subject; bh=7tmFPjV8M2Lx3B/gsex9ygtAi4GAyO2CUR5hzaPWmrY=; b=owEBbQGS/pANAwAIAZydqgc/ZEDZAcsmYgBiRtOfsoOxGQACw0FePTNQ42iGCUudqsPksxx2yZ3J SOKN4lSJATMEAAEIAB0WIQSrWdEr1p4yirVVKBycnaoHP2RA2QUCYkbTnwAKCRCcnaoHP2RA2aPMB/ 9LGTA72k9Xo0pW2lCEEkqTs2Y75Vyi3qFmfiiYCZtJOseGMXarUSESGp1AkQ63NRm9s8ztqfmA7A+a hjpnJgANwJ7jr00iR2kVUv7G1Qiyrmrxapbs6qrzYKCIrdPXc/NQBrq07zeY31kRY9l7mhRNYdglSP omJL7N7ASa0vofKfdWDFoP5cjLCOKIuvYfzs8GgiUIfFO050TUlI5L1BiRh0BiVKhd1t6/tW8LA2Qv qhbfiiYusxxmlDZtq6Mm6Fm9VSAtvmgmmsdjLE0OJ+ejc+dqFxIBLldkyLlGAsPmpjKcHg2mAAp+xT 7mvI2HARGmj5DI41cSvzHqQAqTbMda X-Developer-Key: i=jack@suse.cz; a=openpgp; fpr=93C6099A142276A28BBE35D815BC833443038D8C Content-Transfer-Encoding: 8bit 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") Tested-by: "yukuai (C)" 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); -- 2.34.1