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=-19.4 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,USER_AGENT_GIT autolearn=unavailable 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 A1A74C11F81 for ; Mon, 12 Jul 2021 08:34:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B818611C2 for ; Mon, 12 Jul 2021 08:34:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1377616AbhGLIgL (ORCPT ); Mon, 12 Jul 2021 04:36:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:35402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349299AbhGLHuK (ORCPT ); Mon, 12 Jul 2021 03:50:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 854D3619A7; Mon, 12 Jul 2021 07:43:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626075806; bh=e9KFX+wBWaKEFsGUc51MWBQ9n9ZLQfknFXe1xWLDusc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k7/GOvCpWL39LPlZAoScxRXn7rV29cykAzf1s7uVe/CYCmpygGwNHwG4pz8MnxdZI v3Sub0I7uD0zzyDACkq5IfxR7Z77kAsKqVDQrPFd3x3PDMWt7vl6/vNsCb1Qz0KJ08 6qgQ0UP/aU1GxjbXqKpyK3YqxNJNuzGi9W/GF/Zs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zhang Yi , Jens Axboe , Sasha Levin Subject: [PATCH 5.13 371/800] blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled() Date: Mon, 12 Jul 2021 08:06:34 +0200 Message-Id: <20210712061006.529310849@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zhang Yi [ Upstream commit 1d0903d61e9645c6330b94247b96dd873dfc11c8 ] Now that we disable wbt by simply zero out rwb->wb_normal in wbt_disable_default() when switch elevator to bfq, but it's not safe because it will become false positive if we change queue depth. If it become false positive between wbt_wait() and wbt_track() when submit write request, it will lead to drop rqw->inflight to -1 in wbt_done(), which will end up trigger IO hung. Fix this issue by introduce a new state which mean the wbt was disabled. Fixes: a79050434b45 ("blk-rq-qos: refactor out common elements of blk-wbt") Signed-off-by: Zhang Yi Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com Signed-off-by: Jens Axboe Signed-off-by: Sasha Levin --- block/blk-wbt.c | 5 +++-- block/blk-wbt.h | 1 + 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/block/blk-wbt.c b/block/blk-wbt.c index 42aed0160f86..b098ac6a84f0 100644 --- a/block/blk-wbt.c +++ b/block/blk-wbt.c @@ -77,7 +77,8 @@ enum { static inline bool rwb_enabled(struct rq_wb *rwb) { - return rwb && rwb->wb_normal != 0; + return rwb && rwb->enable_state != WBT_STATE_OFF_DEFAULT && + rwb->wb_normal != 0; } static void wb_timestamp(struct rq_wb *rwb, unsigned long *var) @@ -702,7 +703,7 @@ void wbt_disable_default(struct request_queue *q) rwb = RQWB(rqos); if (rwb->enable_state == WBT_STATE_ON_DEFAULT) { blk_stat_deactivate(rwb->cb); - rwb->wb_normal = 0; + rwb->enable_state = WBT_STATE_OFF_DEFAULT; } } EXPORT_SYMBOL_GPL(wbt_disable_default); diff --git a/block/blk-wbt.h b/block/blk-wbt.h index 16bdc85b8df9..2eb01becde8c 100644 --- a/block/blk-wbt.h +++ b/block/blk-wbt.h @@ -34,6 +34,7 @@ enum { enum { WBT_STATE_ON_DEFAULT = 1, WBT_STATE_ON_MANUAL = 2, + WBT_STATE_OFF_DEFAULT }; struct rq_wb { -- 2.30.2