Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756155AbbGTTjP (ORCPT ); Mon, 20 Jul 2015 15:39:15 -0400 Received: from kanga.kvack.org ([205.233.56.17]:34775 "EHLO kanga.kvack.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752290AbbGTTjN (ORCPT ); Mon, 20 Jul 2015 15:39:13 -0400 Date: Mon, 20 Jul 2015 15:39:12 -0400 From: Benjamin LaHaise To: Oleg Nesterov Cc: Jeff Moyer , Andrew Morton , Joonsoo Kim , Fengguang Wu , Johannes Weiner , Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix Message-ID: <20150720193912.GJ21558@kvack.org> References: <20150716231405.GA25147@redhat.com> <20150716162444.26425f5e227387f1166a6d16@linux-foundation.org> <20150716235227.GA26551@redhat.com> <20150717140615.GA2779@kvack.org> <20150717223147.GA13259@redhat.com> <20150720173311.GA4379@redhat.com> <20150720175145.GH21558@kvack.org> <20150720183150.GA6868@redhat.com> <20150720192440.GA20573@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150720192440.GA20573@redhat.com> User-Agent: Mutt/1.4.2.2i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1545 Lines: 41 On Mon, Jul 20, 2015 at 09:24:40PM +0200, Oleg Nesterov wrote: > On 07/20, Oleg Nesterov wrote: > > > > But again, again, please ignore. This all is off-topic and my understanding > > is very limited. > > Yes, yes, but sorry for noise and let me repeat... > > This memory lives in page-cache/lru, it is visible for shrinker which > will unmap these pages for no reason on memory shortage. IOW, aio fools > the kernel, this memory looks reclaimable but it is not. And we only do > this for migration. And we have the same problem with O_DIRECT. Given the size of the LRU in a modern system, I highly doubt a handful of pages getting scanned is a major problem. If you want to improve this, go ahead, but we need to retain support for page migration as people have run into the need for it. > Even if this is not a problem, this does not look right. So perhaps at > least mapping_set_unevictable() makes sense. But I simply do not know > if migration will work with this change. Nor do I know if that will work. > And I should have changes the subject a long ago... So what do you think > we should do with the build failure? I honestly don't care what of the options you do -- please just don't go about adding BUG()s. -ben > Oleg. -- "Thought is the essence of where you are now." -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/