Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752728AbZIKLMu (ORCPT ); Fri, 11 Sep 2009 07:12:50 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752590AbZIKLMt (ORCPT ); Fri, 11 Sep 2009 07:12:49 -0400 Received: from mail-iw0-f178.google.com ([209.85.223.178]:33674 "EHLO mail-iw0-f178.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751920AbZIKLMt convert rfc822-to-8bit (ORCPT ); Fri, 11 Sep 2009 07:12:49 -0400 X-Greylist: delayed 338 seconds by postgrey-1.27 at vger.kernel.org; Fri, 11 Sep 2009 07:12:48 EDT 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=C3bLTXaQQ8NG1LqjymLCD3u/9W+c3C3aBmzQKLw9MgosLkSHfg00/lZvqBXAVEWRyv MoyQXXIwAUw6lgOE8bi0dy7xIXbhXdracbWcxWtZJhn+SPVRPHJDUiTSfRmHys300/yz aV0Hm524gRznCqOWQ6xU2WSobLU3q5ZvT6JXk= MIME-Version: 1.0 In-Reply-To: References: Date: Fri, 11 Sep 2009 20:07:13 +0900 Message-ID: <82e12e5f0909110407h178ab6e0hbd6ac9e204738ae7@mail.gmail.com> Subject: Re: [PATCH 1/8] mm: munlock use follow_page From: Hiroaki Wakabayashi To: Hugh Dickins Cc: Andrew Morton , Lee Schermerhorn , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Linus Torvalds , Nick Piggin , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org 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 Content-Length: 1605 Lines: 35 2009/9/8 Hugh Dickins : > 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? ?That 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 Reviewed-by: Hiroaki Wakabayashi It very simple and so cool! I have learned something. -- Thanks, Hiroaki Wakabayashi -- 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/