From mboxrd@z Thu Jan 1 00:00:00 1970 From: Guenter Roeck Subject: Re: mmotm 2015-01-22-15-04: qemu failure due to 'mm: memcontrol: remove unnecessary soft limit tree node test' Date: Fri, 23 Jan 2015 08:59:51 -0800 Message-ID: <54C27E07.6000908@roeck-us.net> References: <54c1822d.RtdGfWPekQVAw8Ly%akpm@linux-foundation.org> <20150123050802.GB22751@roeck-us.net> <20150123141817.GA22926@phnom.home.cmpxchg.org> <20150123160204.GA32592@phnom.home.cmpxchg.org> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: akpm@linux-foundation.org, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-next@vger.kernel.org, Stephen Rothwell , mhocko@suse.cz To: Johannes Weiner , Christoph Lameter Return-path: In-Reply-To: <20150123160204.GA32592@phnom.home.cmpxchg.org> Sender: linux-next-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On 01/23/2015 08:02 AM, Johannes Weiner wrote: > On Fri, Jan 23, 2015 at 09:17:44AM -0600, Christoph Lameter wrote: >> On Fri, 23 Jan 2015, Johannes Weiner wrote: >> >>> Is the assumption of this patch wrong? Does the specified node have >>> to be online for the fallback to work? >> >> Nodes that are offline have no control structures allocated and thus >> allocations will likely segfault when the address of the controls >> structure for the node is accessed. >> >> If we wanted to prevent that then every allocation would have to add a >> check to see if the nodes are online which would impact performance. > > Okay, that makes sense, thank you. > > Andrew, can you please drop this patch? > Problem is that there are three patches. 2537ffb mm: memcontrol: consolidate swap controller code 2f9b346 mm: memcontrol: consolidate memory controller initialization a40d0d2 mm: memcontrol: remove unnecessary soft limit tree node test Reverting (or dropping) a40d0d2 alone is not possible since it modifies mem_cgroup_soft_limit_tree_init which is removed by 2f9b346. Guenter