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 991F8C43334 for ; Sat, 4 Jun 2022 02:09:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347939AbiFDCJF (ORCPT ); Fri, 3 Jun 2022 22:09:05 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345631AbiFDCJF (ORCPT ); Fri, 3 Jun 2022 22:09:05 -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 703B835DC0 for ; Fri, 3 Jun 2022 19:09:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1654308543; 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: in-reply-to:in-reply-to:references:references; bh=Wz/tZ37kUmFWQ6HkHJXHebNCC4sxDl8GdAywmW5KYk4=; b=MNga+XtkH9p7T+NhF4oxv2IK8/pYV/PgftB0WY92yt/pkAcHD6iBtkxDbQfxzkghkRrjpr yvbjSXELj9y3NcmjDTdhQAli3u6Fjl7KwzU0sDi8ZGferDFJHuC5Rtnu7OZi5sarORM6qC /781PpEOQFs9szpKr6OhNDEct+KQ694= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-50-AGSMn1-FMN2cGsQOaJpppg-1; Fri, 03 Jun 2022 22:08:58 -0400 X-MC-Unique: AGSMn1-FMN2cGsQOaJpppg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id C57431C0513E; Sat, 4 Jun 2022 02:08:57 +0000 (UTC) Received: from T590 (ovpn-8-17.pek2.redhat.com [10.72.8.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 9D3E02166B26; Sat, 4 Jun 2022 02:08:53 +0000 (UTC) Date: Sat, 4 Jun 2022 10:08:48 +0800 From: Ming Lei To: Waiman Long Cc: Tejun Heo , Jens Axboe , cgroups@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v6 1/3] blk-cgroup: Correctly free percpu iostat_cpu in blkg on error exit Message-ID: References: <20220602192020.166940-1-longman@redhat.com> <20220602192020.166940-2-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220602192020.166940-2-longman@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org 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? Thanks Ming