From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ie0-f181.google.com (mail-ie0-f181.google.com [209.85.223.181]) by kanga.kvack.org (Postfix) with ESMTP id AA92C6B0035 for ; Mon, 30 Jun 2014 22:02:47 -0400 (EDT) Received: by mail-ie0-f181.google.com with SMTP id rl12so81868iec.40 for ; Mon, 30 Jun 2014 19:02:47 -0700 (PDT) Received: from smtp.codeaurora.org (smtp.codeaurora.org. [198.145.11.231]) by mx.google.com with ESMTPS id r10si32036975ico.103.2014.06.30.19.02.46 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Jun 2014 19:02:46 -0700 (PDT) Message-ID: <53B216C5.8020503@codeaurora.org> Date: Mon, 30 Jun 2014 19:02:45 -0700 From: Laura Abbott 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> <53B209BA.8010106@lge.com> In-Reply-To: <53B209BA.8010106@lge.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Gioh Kim , Michal Nazarewicz , Marek Szyprowski , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Joonsoo Kim , Mel Gorman , =?UTF-8?B?7J206rG07Zi4?= , Hugh Dickins On 6/30/2014 6:07 PM, Gioh Kim wrote: > 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? > > __evict_bh_lru is called via on_each_cpu_cond which I believe will disable irqs. I based the code on the existing invalidate_bh_lru which did not take the bh_lru_lock either. It's possible I missed something though. Thanks, Laura -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- 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