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 486D2C433EF for ; Sat, 4 Jun 2022 02:47:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232220AbiFDCrx (ORCPT ); Fri, 3 Jun 2022 22:47:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58614 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231513AbiFDCrx (ORCPT ); Fri, 3 Jun 2022 22:47:53 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id E81E41DA63 for ; Fri, 3 Jun 2022 19:47:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1654310871; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Cqh4lNnb8LUprz/k7VVRsZMriLZ9YvGxKq09h6b6YYk=; b=Zf+QEeWfXLxS/vSJlzrKJtdHkrfBSIF/gs4eYGyZhbPk7UBvRmYvtasUKIa0qd6+CgzNqT nVV1UhFOG8ELLrO6lY+WMRalHs8Dimac3iR/jQvs5Z0bujsktF2CZNBWJPHRc2VqvIrnfJ 0x2XX+5fvWMurUnosRDnhkwovJbwCgc= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-656-wm0ujGPvM8e41O88O94wtA-1; Fri, 03 Jun 2022 22:47:49 -0400 X-MC-Unique: wm0ujGPvM8e41O88O94wtA-1 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1FB7C802809; Sat, 4 Jun 2022 02:47:49 +0000 (UTC) Received: from [10.22.11.59] (unknown [10.22.11.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id D0EB4492C3B; Sat, 4 Jun 2022 02:47:48 +0000 (UTC) Message-ID: <9fe80bd8-7733-066e-d8eb-5e5bab221e45@redhat.com> Date: Fri, 3 Jun 2022 22:47:48 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 Subject: Re: [PATCH v6 1/3] blk-cgroup: Correctly free percpu iostat_cpu in blkg on error exit Content-Language: en-US To: Ming Lei Cc: Tejun Heo , Jens Axboe , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220602192020.166940-1-longman@redhat.com> <20220602192020.166940-2-longman@redhat.com> From: Waiman Long In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.85 on 10.11.54.9 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 6/3/22 22:08, Ming Lei wrote: > On Thu, Jun 02, 2022 at 03:20:18PM -0400, Waiman Long wrote: >> Commit f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup >> rstat") changes block cgroup IO stats to use the rstat APIs. It added >> a new percpu iostat_cpu field into blkg. The blkg_alloc() was modified >> to allocate the new percpu iostat_cpu but didn't free it when an error >> happened. Fix this by freeing the percpu iostat_cpu on error exit. >> >> Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") >> Signed-off-by: Waiman Long >> Acked-by: Tejun Heo >> --- >> block/blk-cgroup.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c >> index 40161a3f68d0..acd9b0aa8dc8 100644 >> --- a/block/blk-cgroup.c >> +++ b/block/blk-cgroup.c >> @@ -219,11 +219,11 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, >> return NULL; >> >> if (percpu_ref_init(&blkg->refcnt, blkg_release, 0, gfp_mask)) >> - goto err_free; >> + goto err_free_blkg; >> >> blkg->iostat_cpu = alloc_percpu_gfp(struct blkg_iostat_set, gfp_mask); >> if (!blkg->iostat_cpu) >> - goto err_free; >> + goto err_free_blkg; >> >> if (!blk_get_queue(q)) >> goto err_free; >> @@ -259,6 +259,9 @@ static struct blkcg_gq *blkg_alloc(struct blkcg *blkcg, struct request_queue *q, >> return blkg; >> >> err_free: >> + free_percpu(blkg->iostat_cpu); >> + >> +err_free_blkg: >> blkg_free(blkg); > Hi Waiman, > > But blkg_free() frees blkg->iostat_cpu via blkg_free_workfn(), so I am > confused where the leak is in failure path? Yes, you are right. I have overlooked that. So this patch isn't really necessary. Thanks for correcting me. Cheers, Longman