From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: Re: [PATCH v6 1/3] blk-cgroup: Correctly free percpu iostat_cpu in blkg on error exit Date: Sat, 4 Jun 2022 10:08:48 +0800 Message-ID: References: <20220602192020.166940-1-longman@redhat.com> <20220602192020.166940-2-longman@redhat.com> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1654308539; 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=SpoAaKQoX+B91ClagWDPNP/91degqU/dkisaqEVEXC4yRxO+SeK6ReIt0uK90+mpqh48Gu pMX8r6BraWgv4h6sbbwr4oBGF1hJqizYDyHjE1AHhZ/3nqFprBTMBa0FQzuUG+ss/xIlc3 3OsyoMqTqjkynDy34XT5BjtysTG8s40= Content-Disposition: inline In-Reply-To: <20220602192020.166940-2-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Waiman Long Cc: Tejun Heo , Jens Axboe , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.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