From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753514AbcHPRkB (ORCPT <rfc822;w@1wt.eu>);
	Tue, 16 Aug 2016 13:40:01 -0400
Received: from gum.cmpxchg.org ([85.214.110.215]:58292 "EHLO gum.cmpxchg.org"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S1752041AbcHPRjs (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 16 Aug 2016 13:39:48 -0400
Date: Tue, 16 Aug 2016 13:36:03 -0400
From: Johannes Weiner <hannes@cmpxchg.org>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Brenden Blanco <bblanco@plumgrid.com>, Michal Hocko <mhocko@kernel.org>,
        Vladimir Davydov <vdavydov@virtuozzo.com>,
        linux-kernel@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subject: Re: uprobes: memory leak in enable/disable loop
Message-ID: <20160816173603.GA18078@cmpxchg.org>
References: <20160815205810.GA22619@gmail.com>
 <20160816141350.GA17006@redhat.com>
 <20160816142511.GB17006@redhat.com>
 <20160816143407.GC17006@redhat.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20160816143407.GC17006@redhat.com>
User-Agent: Mutt/1.6.2 (2016-07-01)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Tue, Aug 16, 2016 at 04:34:08PM +0200, Oleg Nesterov wrote:
> @@ -172,8 +172,10 @@ static int __replace_page(struct vm_area
>  	mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
>  	err = -EAGAIN;
>  	ptep = page_check_address(page, mm, addr, &ptl, 0);
> -	if (!ptep)
> +	if (!ptep) {
> +		mem_cgroup_cancel_charge(kpage, memcg, false);
>  		goto unlock;
> +	}
>  
>  	get_page(kpage);
>  	page_add_new_anon_rmap(kpage, vma, addr, false);
> @@ -200,7 +202,6 @@ static int __replace_page(struct vm_area
>  
>  	err = 0;
>   unlock:
> -	mem_cgroup_cancel_charge(kpage, memcg, false);

Ouch. I must have mistaken this for an exclusive error path.

The patch looks good, thank you.

Reviewed-by: Johannes Weiner <hannes@cmpxchg.org>
Fixes: 00501b531c47 ("mm: memcontrol: rewrite charge API")
Cc: stable@vger.kernel.org # 3.17+