From patchwork Tue Nov 29 03:01:40 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kemeng Shi X-Patchwork-Id: 13058149 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 CCF38C4332F for ; Tue, 29 Nov 2022 03:02:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235307AbiK2DB4 (ORCPT ); Mon, 28 Nov 2022 22:01:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235291AbiK2DBy (ORCPT ); Mon, 28 Nov 2022 22:01:54 -0500 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1509845097; Mon, 28 Nov 2022 19:01:54 -0800 (PST) Received: from kwepemi500016.china.huawei.com (unknown [172.30.72.57]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4NLnCt1XVRz15MpD; Tue, 29 Nov 2022 11:01:14 +0800 (CST) Received: from huawei.com (10.174.178.129) by kwepemi500016.china.huawei.com (7.221.188.220) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Tue, 29 Nov 2022 11:01:51 +0800 From: Kemeng Shi To: , , CC: , , , Subject: [PATCH v2 03/10] blk-throttle: ignore cgroup without io queued in blk_throtl_cancel_bios Date: Tue, 29 Nov 2022 11:01:40 +0800 Message-ID: <20221129030147.27400-4-shikemeng@huawei.com> X-Mailer: git-send-email 2.14.1.windows.1 In-Reply-To: <20221129030147.27400-1-shikemeng@huawei.com> References: <20221129030147.27400-1-shikemeng@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.174.178.129] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To kwepemi500016.china.huawei.com (7.221.188.220) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org Ignore cgroup without io queued in blk_throtl_cancel_bios for two reasons: 1. Save cpu cycle for trying to dispatch cgroup which is no io queued. 2. Avoid non-consistent state that cgroup is inserted to service queue without THROTL_TG_PENDING set as tg_update_disptime will unconditional re-insert cgroup to service queue. If we are on the default hierarchy, IO dispatched from child in tg_dispatch_one_bio will trigger inserting cgroup to service queue without erase first and ruin the tree. Signed-off-by: Kemeng Shi Acked-by: Tejun Heo --- block/blk-throttle.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/block/blk-throttle.c b/block/blk-throttle.c index d516a37e82fb..ee7dc1a0adfd 100644 --- a/block/blk-throttle.c +++ b/block/blk-throttle.c @@ -1738,7 +1738,18 @@ void blk_throtl_cancel_bios(struct gendisk *disk) * Set the flag to make sure throtl_pending_timer_fn() won't * stop until all throttled bios are dispatched. */ - blkg_to_tg(blkg)->flags |= THROTL_TG_CANCELING; + tg->flags |= THROTL_TG_CANCELING; + + /* + * Do not dispatch cgroup without THROTL_TG_PENDING or cgroup + * will be inserted to service queue without THROTL_TG_PENDING + * set in tg_update_disptime below. Then IO dispatched from + * child in tg_dispatch_one_bio will trigger double insertion + * and corrupt the tree. + */ + if (!(tg->flags & THROTL_TG_PENDING)) + continue; + /* * Update disptime after setting the above flag to make sure * throtl_select_dispatch() won't exit without dispatching.