From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f54.google.com (mail-pa0-f54.google.com [209.85.220.54]) by kanga.kvack.org (Postfix) with ESMTP id 2E1336B0035 for ; Mon, 30 Jun 2014 21:07:10 -0400 (EDT) Received: by mail-pa0-f54.google.com with SMTP id et14so9650818pad.27 for ; Mon, 30 Jun 2014 18:07:09 -0700 (PDT) Received: from lgeamrelo02.lge.com (lgeamrelo02.lge.com. [156.147.1.126]) by mx.google.com with ESMTP id go6si25017679pac.116.2014.06.30.18.07.08 for ; Mon, 30 Jun 2014 18:07:09 -0700 (PDT) Message-ID: <53B209BA.8010106@lge.com> Date: Tue, 01 Jul 2014 10:07:06 +0900 From: Gioh Kim MIME-Version: 1.0 Subject: Re: [RFC] CMA page migration failure due to buffers on bh_lru References: <53A8D092.4040801@lge.com> <53ACAB82.6020201@lge.com> <53B06DD0.8030106@codeaurora.org> In-Reply-To: <53B06DD0.8030106@codeaurora.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: Laura Abbott , Michal Nazarewicz , Marek Szyprowski , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Joonsoo Kim , Mel Gorman , =?UTF-8?B?7J206rG07Zi4?= , Hugh Dickins Hi,Laura. I have a question. Does the __evict_bh_lru() not need bh_lru_lock()? The get_cpu_var() has already preenpt_disable() and can prevent other thread. But get_cpu_var cannot prevent IRQ context such like page-fault. I think if a page-fault occured and a file is read in IRQ context it can change cpu-lru. Is my concern correct? 2014-06-30 i??i ? 4:49, Laura Abbott i?' e,?: > (cc-ing Hugh since he had comments on the patch before) > > On 6/26/2014 4:23 PM, Gioh Kim wrote: >> >> >> 2014-06-27 i??i ? 12:57, Michal Nazarewicz i?' e,?: >>> On Tue, Jun 24 2014, Gioh Kim wrote: >>>> Hello, >>>> >>>> I am trying to apply CMA feature for my platform. >>>> My kernel version, 3.10.x, is not allocating memory from CMA area so that I applied >>>> a Joonsoo Kim's patch (https://lkml.org/lkml/2014/5/28/64). >>>> Now my platform can use CMA area effectively. >>>> >>>> But I have many failures to allocate memory from CMA area. >>>> I found the same situation to Laura Abbott's patch descrbing, >>>> https://lkml.org/lkml/2012/8/31/313, >>>> that releases buffer-heads attached at CPU's LRU list. >>>> >>>> If Joonsoo's patch is applied and/or CMA feature is applied more and more, >>>> buffer-heads problem is going to be serious definitely. >>>> >>>> Please look into the Laura's patch again. >>>> I think it must be applied with Joonsoo's patch. >>> >>> Just to make sure I understood you correctly, you're saying Laura's >>> patch at fixes your issue? >>> >> >> Yes, it is. > > I submitted this before and it was suggested that this was more > related to filesystems > > http://marc.info/?l=linaro-mm-sig&m=137645770708817&w=2 > > I never saw more discussion and pushed this into the 'CMA hacks' pile. > So far we've been keeping the patch out of tree and it's useful to know > that others have found the same problem. I'm willing to resubmit the > patch for further discussion. > > Thanks, > Laura > -- 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