From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 9613A6B02C4 for ; Tue, 2 May 2017 10:21:09 -0400 (EDT) Received: by mail-pg0-f71.google.com with SMTP id 7so11625455pgg.19 for ; Tue, 02 May 2017 07:21:09 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTPS id s10si8210486pgs.322.2017.05.02.07.21.08 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 May 2017 07:21:08 -0700 (PDT) From: "Christopherson, Sean J" Subject: RE: [PATCH 0/2] mm/memcontrol: fix reclaim bugs in mem_cgroup_iter Date: Tue, 2 May 2017 14:20:45 +0000 Message-ID: <37306EFA9975BE469F115FDE982C075B9B704A9A@ORSMSX108.amr.corp.intel.com> References: <1493416547-19212-1-git-send-email-sean.j.christopherson@intel.com> <20170502140357.GL14593@dhcp22.suse.cz> In-Reply-To: <20170502140357.GL14593@dhcp22.suse.cz> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: 'Michal Hocko' Cc: "hannes@cmpxchg.org" , "vdavydov.dev@gmail.com" , "cgroups@vger.kernel.org" , "linux-mm@kvack.org" Michal Hocko wrote: > On Fri 28-04-17 14:55:45, Sean Christopherson wrote: > > This patch set contains two bug fixes for mem_cgroup_iter(). The bugs > > were found by code inspection and were confirmed via synthetic testing > > that forcefully setup the failing conditions. >=20 > I assume that you added some artificial sleeps to make those races more > probable, right? Or did you manage to hit those issue solely from the > userspace? I will have a look at those patches. It has been some time > since I've had it cached. It is pretty subtle code so I would like to > understand the urgency before I dive into this further. > --=20 > Michal Hocko > SUSE Labs The code to prove the bugs is completely artificial, it's basically a unit test for mem_cgroup_iter() that uses a thread barrier to all but guarantee two threads will call mem_cgroup_iter() simultaneously. I haven't even attempted to hit this via the actual userspace flow. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org