From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id B7E506B004F for ; Wed, 9 Sep 2009 11:59:57 -0400 (EDT) Received: by ywh32 with SMTP id 32so3499432ywh.11 for ; Wed, 09 Sep 2009 08:59:56 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: Date: Thu, 10 Sep 2009 00:59:56 +0900 Message-ID: <28c262360909090859l6e94c0eekc38bd2670d7fc79e@mail.gmail.com> Subject: Re: [PATCH 1/8] mm: munlock use follow_page From: Minchan Kim Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Hugh Dickins Cc: Andrew Morton , Hiroaki Wakabayashi , Lee Schermerhorn , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Linus Torvalds , Nick Piggin , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tue, Sep 8, 2009 at 6:29 AM, Hugh Dickins w= rote: > Hiroaki Wakabayashi points out that when mlock() has been interrupted > by SIGKILL, the subsequent munlock() takes unnecessarily long because > its use of __get_user_pages() insists on faulting in all the pages > which mlock() never reached. > > It's worse than slowness if mlock() is terminated by Out Of Memory kill: > the munlock_vma_pages_all() in exit_mmap() insists on faulting in all the > pages which mlock() could not find memory for; so innocent bystanders are > killed too, and perhaps the system hangs. > > __get_user_pages() does a lot that's silly for munlock(): so remove the > munlock option from __mlock_vma_pages_range(), and use a simple loop of > follow_page()s in munlock_vma_pages_range() instead; ignoring absent > pages, and not marking present pages as accessed or dirty. > > (Change munlock() to only go so far as mlock() reached? =A0That does not > work out, given the convention that mlock() claims complete success even > when it has to give up early - in part so that an underlying file can be > extended later, and those pages locked which earlier would give SIGBUS.) > > Signed-off-by: Hugh Dickins > Cc: stable@kernel.org Reviewed-by: Minchan Kim It looks better than old Hiroaki's one. --=20 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/ . Don't email: email@kvack.org