From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qe0-f46.google.com (mail-qe0-f46.google.com [209.85.128.46]) by kanga.kvack.org (Postfix) with ESMTP id D69436B00B4 for ; Mon, 9 Dec 2013 11:00:25 -0500 (EST) Received: by mail-qe0-f46.google.com with SMTP id a11so2862693qen.5 for ; Mon, 09 Dec 2013 08:00:25 -0800 (PST) Received: from b232-35.smtp-out.amazonses.com (b232-35.smtp-out.amazonses.com. [199.127.232.35]) by mx.google.com with ESMTP id 2si3778593qcp.80.2013.12.09.08.00.24 for ; Mon, 09 Dec 2013 08:00:25 -0800 (PST) Date: Mon, 9 Dec 2013 16:00:24 +0000 From: Christoph Lameter Subject: Re: [PATCH 14/15] mm: fix TLB flush race between migration, and change_protection_range In-Reply-To: <52A29278.9000609@redhat.com> Message-ID: <00000142d816866f-615798f8-74d8-401c-b35a-88aa1dbc8eb5-000000@email.amazonses.com> References: <1386060721-3794-1-git-send-email-mgorman@suse.de> <1386060721-3794-15-git-send-email-mgorman@suse.de> <529E641A.7040804@redhat.com> <20131203234637.GS11295@suse.de> <529F3D51.1090203@redhat.com> <20131204160741.GC11295@suse.de> <20131206141331.10880d2b@annuminas.surriel.com> <00000142c99cf5b0-69cc9987-aa36-4889-af6a-1a45032d0d13-000000@email.amazonses.com> <52A23FD1.3040102@redhat.com> <00000142ca7218fe-a5566a24-0ef5-4545-8a98-d33116b7d703-000000@email.amazonses.com> <52A29278.9000609@redhat.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Mel Gorman , Alex Thorlton , Linux-MM , LKML On Fri, 6 Dec 2013, Rik van Riel wrote: > > Ok then what are you trying to fix? > > It would help if you had actually read the patch. I read the patch. Please update the documentation to accurately describe the race. >>From what I can see this race affects only huge pages and the basic issue seems to be that huge pages do not use migration entries but directly replace the pmd (migrate_misplaced_transhuge_page() f.e.). That is not safe and there may be multiple other races as we add more general functionality to huge pages. An intermediate stage is needed that allows the clearing out of remote tlb entries before the new tlb entry becomes visible. Then you wont need this code anymore. -- 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