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 X-Spam-Level: X-Spam-Status: No, score=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 255A3C4338F for ; Wed, 18 Aug 2021 01:09:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B13860FD7 for ; Wed, 18 Aug 2021 01:09:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237398AbhHRBKY (ORCPT ); Tue, 17 Aug 2021 21:10:24 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:45127 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237387AbhHRBKY (ORCPT ); Tue, 17 Aug 2021 21:10:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629248990; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=RCCWvDjY3Q5IUVIs6QPft/4AsaIoSIpdIehWy1LmRPw=; b=KVIlxSHlxcIMo90i6tn1bknsi0b7R2emGgsTPjFMxQpxWC/+1fpPXthsx4rtlOk9WBJwsM iEq7lO7+NgYLpD+UOuZBDlItPioApbQhzD3GY9vnrp9GZtY0Q/mhIisg4a6lt0s5aMxM2X YigYfaHbA6An7Jg4vhXZB+UkOWE9Fy4= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-595-EplxXfUgPSybCuxqFm9pLA-1; Tue, 17 Aug 2021 21:09:46 -0400 X-MC-Unique: EplxXfUgPSybCuxqFm9pLA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4EFF5760C0; Wed, 18 Aug 2021 01:09:45 +0000 (UTC) Received: from localhost (ovpn-8-28.pek2.redhat.com [10.72.8.28]) by smtp.corp.redhat.com (Postfix) with ESMTP id DCFD91B46B; Wed, 18 Aug 2021 01:09:39 +0000 (UTC) From: Ming Lei To: Jens Axboe Cc: linux-block@vger.kernel.org, Christoph Hellwig , Bart Van Assche , John Garry , Ming Lei , "Blank-Burian, Markus, Dr." , Yufen Yu Subject: [PATCH] blk-mq: fix is_flush_rq Date: Wed, 18 Aug 2021 09:09:25 +0800 Message-Id: <20210818010925.607383-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org is_flush_rq() is called from bt_iter()/bt_tags_iter(), and runs the following check: hctx->fq->flush_rq == req but the passed hctx from bt_iter()/bt_tags_iter() may be NULL because: 1) memory re-order in blk_mq_rq_ctx_init(): rq->mq_hctx = data->hctx; ... refcount_set(&rq->ref, 1); OR 2) tag re-use and ->rqs[] isn't updated with new request. Fix the issue by re-writing is_flush_rq() as: return rq->end_io == flush_end_io; which turns out simpler to follow and immune to data race since we have ordered WRITE rq->end_io and refcount_set(&rq->ref, 1). Fixes: 2e315dc07df0 ("blk-mq: grab rq->refcount before calling ->fn in blk_mq_tagset_busy_iter") Cc: "Blank-Burian, Markus, Dr." Cc: Yufen Yu Signed-off-by: Ming Lei --- block/blk-flush.c | 5 +++++ block/blk-mq.c | 2 +- block/blk.h | 6 +----- 3 files changed, 7 insertions(+), 6 deletions(-) diff --git a/block/blk-flush.c b/block/blk-flush.c index 4912c8dbb1d8..4201728bf3a5 100644 --- a/block/blk-flush.c +++ b/block/blk-flush.c @@ -262,6 +262,11 @@ static void flush_end_io(struct request *flush_rq, blk_status_t error) spin_unlock_irqrestore(&fq->mq_flush_lock, flags); } +bool is_flush_rq(struct request *rq) +{ + return rq->end_io == flush_end_io; +} + /** * blk_kick_flush - consider issuing flush request * @q: request_queue being kicked diff --git a/block/blk-mq.c b/block/blk-mq.c index b5237211ccb7..6d7395ad6d94 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -911,7 +911,7 @@ static bool blk_mq_req_expired(struct request *rq, unsigned long *next) void blk_mq_put_rq_ref(struct request *rq) { - if (is_flush_rq(rq, rq->mq_hctx)) + if (is_flush_rq(rq)) rq->end_io(rq, 0); else if (refcount_dec_and_test(&rq->ref)) __blk_mq_free_request(rq); diff --git a/block/blk.h b/block/blk.h index 56f33fbcde59..d4fb5b72d12b 100644 --- a/block/blk.h +++ b/block/blk.h @@ -44,11 +44,7 @@ static inline void __blk_get_queue(struct request_queue *q) kobject_get(&q->kobj); } -static inline bool -is_flush_rq(struct request *req, struct blk_mq_hw_ctx *hctx) -{ - return hctx->fq->flush_rq == req; -} +bool is_flush_rq(struct request *req); struct blk_flush_queue *blk_alloc_flush_queue(int node, int cmd_size, gfp_t flags); -- 2.31.1