From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754423AbZHYEqV (ORCPT ); Tue, 25 Aug 2009 00:46:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754379AbZHYEqT (ORCPT ); Tue, 25 Aug 2009 00:46:19 -0400 Received: from mail-iw0-f204.google.com ([209.85.223.204]:57086 "EHLO mail-iw0-f204.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752342AbZHYEqS convert rfc822-to-8bit (ORCPT ); Tue, 25 Aug 2009 00:46:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=s0/t3lOzy45yKvkvUOog/3eVS1uZiKHffY5DV4BguI4bVMkRYWeSAMixroMGL/LFkq 2q/iDgn9xDMx1bZz7A2Vyx6rLowQxHiw7CXlKgc2G/2+da9o8gJUOvJPSkLTqXDojtF8 yjqgo+43VZKkRP34KSznrmeBqj+nwz2DmLkgs= MIME-Version: 1.0 In-Reply-To: <2f11576a0908232113w71676aatf22eb6d431501fd0@mail.gmail.com> References: <82e12e5f0908220954p7019fb3dg15f9b99bb7e55a8c@mail.gmail.com> <28c262360908231844o3df95b14v15b2d4424465f033@mail.gmail.com> <20090824105139.c2ab8403.kamezawa.hiroyu@jp.fujitsu.com> <2f11576a0908232113w71676aatf22eb6d431501fd0@mail.gmail.com> Date: Tue, 25 Aug 2009 13:46:19 +0900 Message-ID: <82e12e5f0908242146uad0f314hcbb02fcc999a1d32@mail.gmail.com> Subject: Re: [PATCH] mm: make munlock fast when mlock is canceled by sigkill From: Hiroaki Wakabayashi To: KOSAKI Motohiro Cc: KAMEZAWA Hiroyuki , Minchan Kim , Andrew Morton , LKML , linux-mm@kvack.org, Paul Menage , Ying Han , Pekka Enberg , Lee Schermerhorn Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thank you for reviews. >>> > @@ -254,6 +254,7 @@ static inline void >>> > mminit_validate_memmodel_limits(unsigned long *start_pfn, >>> >  #define GUP_FLAGS_FORCE                  0x2 >>> >  #define GUP_FLAGS_IGNORE_VMA_PERMISSIONS 0x4 >>> >  #define GUP_FLAGS_IGNORE_SIGKILL         0x8 >>> > +#define GUP_FLAGS_ALLOW_NULL             0x10 >>> > >>> >>> I am worried about adding new flag whenever we need it. >>> But I think this case makes sense to me. >>> In addition, I guess ZERO page can also use this flag. >>> >>> Kame. What do you think about it? >>> >> I do welcome this ! >> Then, I don't have to take care of mlock/munlock in ZERO_PAGE patch. >> >> And without this patch, munlock() does copy-on-write just for unpinning memory. >> So, this patch shows some right direction, I think. >> >> One concern is flag name, ALLOW_NULL sounds not very good. >> >>  GUP_FLAGS_NOFAULT ? >> >> I wonder we can remove a hack of FOLL_ANON for core-dump by this flag, too. > > Yeah, GUP_FLAGS_NOFAULT is better. Me too. I will change this flag name. > Plus, this patch change __get_user_pages() return value meaning IOW. > after this patch, it can return following value, > >  return value: 3 >  pages[0]: hoge-page >  pages[1]: null >  pages[2]: fuga-page > > but, it can be > >  return value: 2 >  pages[0]: hoge-page >  pages[1]: fuga-page > > no? I did misunderstand mean of get_user_pages()'s return value. When I try to change __get_user_pages(), I got problem. If remove NULLs from pages, __mlock_vma_pages_range() cannot know how long __get_user_pages() readed. So, I have to get the virtual address of the page from vma and page. Because __mlock_vma_pages_range() have to call __get_user_pages() many times with different `start' argument. I try to use page_address_in_vma(), but it failed. (page_address_in_vma() returned -EFAULT) I cannot find way to solve this problem. Are there good ideas? Please give me some ideas. Thanks. -- Hiroaki Wakabayashi