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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 F0FD1C4CEC4 for ; Mon, 16 Sep 2019 01:53:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD2AC2067D for ; Mon, 16 Sep 2019 01:53:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728040AbfIPBxy (ORCPT ); Sun, 15 Sep 2019 21:53:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46776 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727415AbfIPBxy (ORCPT ); Sun, 15 Sep 2019 21:53:54 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C90F318CB8F5; Mon, 16 Sep 2019 01:53:53 +0000 (UTC) Received: from [10.72.12.58] (ovpn-12-58.pek2.redhat.com [10.72.12.58]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3A573600CD; Mon, 16 Sep 2019 01:53:48 +0000 (UTC) Subject: Re: [RFC PATCH] blk-mq: Avoid memory reclaim when allocating request map To: Ming Lei Cc: josef@toxicpanda.com, axboe@kernel.dk, mchristi@redhat.com, linux-block@vger.kernel.org, Gabriel Krisman Bertazi References: <20190915122656.11376-1-xiubli@redhat.com> <20190916014915.GB5162@ming.t460p> From: Xiubo Li Message-ID: <4a0a4ffb-3e5e-4fea-6436-1720c52243aa@redhat.com> Date: Mon, 16 Sep 2019 09:53:46 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20190916014915.GB5162@ming.t460p> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.63]); Mon, 16 Sep 2019 01:53:53 +0000 (UTC) Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 2019/9/16 9:49, Ming Lei wrote: > On Sun, Sep 15, 2019 at 05:56:56PM +0530, xiubli@redhat.com wrote: >> From: Xiubo Li >> >> For some storage drivers, such as the nbd, when there has new socket >> connections added, it will update the hardware queue number by calling >> blk_mq_update_nr_hw_queues(), in which it will freeze all the queues >> first. And then tries to do the hardware queue updating stuff. >> >> But int blk_mq_alloc_rq_map()-->blk_mq_init_tags(), when allocating >> memory for tags, it may cause the mm do the memories direct reclaiming, >> since the queues has been freezed, so if needs to flush the page cache >> to disk, it will stuck in generic_make_request()-->blk_queue_enter() by >> waiting the queues to be unfreezed and then cause deadlock here. >> >> Since the memory size requested here is a small one, which will make >> it not that easy to happen with a large size, but in theory this could >> happen when the OS is running in pressure and out of memory. >> >> Gabriel Krisman Bertazi has hit the similar issue by fixing it in >> commit 36e1f3d10786 ("blk-mq: Avoid memory reclaim when remapping >> queues"), but might forget this part. >> >> Signed-off-by: Xiubo Li >> CC: Gabriel Krisman Bertazi >> --- >> block/blk-mq-tag.c | 5 +++-- >> block/blk-mq-tag.h | 5 ++++- >> block/blk-mq.c | 3 ++- >> 3 files changed, 9 insertions(+), 4 deletions(-) >> >> diff --git a/block/blk-mq-tag.c b/block/blk-mq-tag.c >> index 008388e82b5c..04ee0e4c3fa1 100644 >> --- a/block/blk-mq-tag.c >> +++ b/block/blk-mq-tag.c >> @@ -462,7 +462,8 @@ static struct blk_mq_tags *blk_mq_init_bitmap_tags(struct blk_mq_tags *tags, >> >> struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, >> unsigned int reserved_tags, >> - int node, int alloc_policy) >> + int node, int alloc_policy, >> + gfp_t flags) >> { >> struct blk_mq_tags *tags; >> >> @@ -471,7 +472,7 @@ struct blk_mq_tags *blk_mq_init_tags(unsigned int total_tags, >> return NULL; >> } >> >> - tags = kzalloc_node(sizeof(*tags), GFP_KERNEL, node); >> + tags = kzalloc_node(sizeof(*tags), flags, node); >> if (!tags) >> return NULL; >> >> diff --git a/block/blk-mq-tag.h b/block/blk-mq-tag.h >> index 61deab0b5a5a..296e0bc97126 100644 >> --- a/block/blk-mq-tag.h >> +++ b/block/blk-mq-tag.h >> @@ -22,7 +22,10 @@ struct blk_mq_tags { >> }; >> >> >> -extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, unsigned int reserved_tags, int node, int alloc_policy); >> +extern struct blk_mq_tags *blk_mq_init_tags(unsigned int nr_tags, >> + unsigned int reserved_tags, >> + int node, int alloc_policy, >> + gfp_t flags); >> extern void blk_mq_free_tags(struct blk_mq_tags *tags); >> >> extern unsigned int blk_mq_get_tag(struct blk_mq_alloc_data *data); >> diff --git a/block/blk-mq.c b/block/blk-mq.c >> index 240416057f28..9c52e4dfe132 100644 >> --- a/block/blk-mq.c >> +++ b/block/blk-mq.c >> @@ -2090,7 +2090,8 @@ struct blk_mq_tags *blk_mq_alloc_rq_map(struct blk_mq_tag_set *set, >> node = set->numa_node; >> >> tags = blk_mq_init_tags(nr_tags, reserved_tags, node, >> - BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags)); >> + BLK_MQ_FLAG_TO_ALLOC_POLICY(set->flags), >> + GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY); > Now, there are three uses on 'GFP_NOIO | __GFP_NOWARN | __GFP_NORETRY', > and code gets cleaner if you make it as one const variable in > blk_mq_alloc_rq_map. @Ming Lei Yeah, this makes sense and will post a V2 to fix it. Thanks very much. BRs Xiubo > Otherwise, looks fine: > > Reviewed-by: Ming Lei > > > thanks, > Ming