From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx189.postini.com [74.125.245.189]) by kanga.kvack.org (Postfix) with SMTP id BB61F6B004D for ; Thu, 10 May 2012 20:49:59 -0400 (EDT) Message-ID: <4FAC623E.7090209@kernel.org> Date: Fri, 11 May 2012 09:50:06 +0900 From: Minchan Kim MIME-Version: 1.0 Subject: Re: [PATCH 2/2 v3] drm/exynos: added userptr feature. References: <1335188594-17454-4-git-send-email-inki.dae@samsung.com> <1336544259-17222-1-git-send-email-inki.dae@samsung.com> <1336544259-17222-3-git-send-email-inki.dae@samsung.com> <001501cd2e4d$c7dbc240$579346c0$%dae@samsung.com> <4FAB4AD8.2010200@kernel.org> <002401cd2e7a$1e8b0ed0$5ba12c70$%dae@samsung.com> <4FAB68CF.8000404@kernel.org> <4FAB782C.306@kernel.org> <003301cd2e89$13f78c00$3be6a400$%dae@samsung.com> <4FAC0091.7070606@gmail.com> In-Reply-To: <4FAC0091.7070606@gmail.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: Inki Dae , 'InKi Dae' , 'Jerome Glisse' , airlied@linux.ie, dri-devel@lists.freedesktop.org, kyungmin.park@samsung.com, sw0312.kim@samsung.com, linux-mm@kvack.org Hi KOSAKI, On 05/11/2012 02:53 AM, KOSAKI Motohiro wrote: >>>> let's assume that one application want to allocate user space memory >>>> region using malloc() and then write something on the region. as you >>>> may know, user space buffer doen't have real physical pages once >>>> malloc() call so if user tries to access the region then page fault >>>> handler would be triggered >>> >>> >>> Understood. >>> >>>> and then in turn next process like swap in to fill physical frame >>>> number >>> into entry of the page faulted. >>> >>> >>> Sorry, I can't understand your point due to my poor English. >>> Could you rewrite it easiliy? :) >>> >> >> Simply saying, handle_mm_fault would be called to update pte after >> finding >> vma and checking access right. and as you know, there are many cases to >> process page fault such as COW or demand paging. > > Hmm. If I understand correctly, you guys misunderstand mlock. it doesn't > page pinning > nor prevent pfn change. It only guarantee to don't make swap out. e.g. Symantic point of view, you're right but the implementation makes sure page pinning. > memory campaction > feature may automatically change page physical address. I tried it last year but decided drop by realtime issue. https://lkml.org/lkml/2011/8/29/295 so I think mlock is a kind of page pinning. If elsewhere I don't realized is doing, that place should be fixed. Or my above patch should go ahead. > > > -- > 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/ . > Fight unfair telecom internet charges in Canada: sign > http://stopthemeter.ca/ > Don't email: email@kvack.org > -- Kind regards, Minchan Kim -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org