From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx167.postini.com [74.125.245.167]) by kanga.kvack.org (Postfix) with SMTP id 484616B005D for ; Sat, 5 Jan 2013 21:59:54 -0500 (EST) Received: by mail-ie0-f176.google.com with SMTP id 13so21426037iea.35 for ; Sat, 05 Jan 2013 18:59:53 -0800 (PST) Message-ID: <1357441197.9001.6.camel@kernel.cn.ibm.com> Subject: Re: [PATCH 0/2] pageattr fixes for pmd/pte_present From: Simon Jeons Date: Sat, 05 Jan 2013 20:59:57 -0600 In-Reply-To: <1355767224-13298-1-git-send-email-aarcange@redhat.com> References: <1355767224-13298-1-git-send-email-aarcange@redhat.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: linux-mm@kvack.org, Andi Kleen , Andrew Morton , Shaohua Li , "H. Peter Anvin" , Mel Gorman , Hugh Dickins What's the status of these two patches? On Mon, 2012-12-17 at 19:00 +0100, Andrea Arcangeli wrote: > Hi, > > I got a report for a minor regression introduced by commit > 027ef6c87853b0a9df53175063028edb4950d476. > > So the problem is, pageattr creates kernel pagetables (pte and pmds) > that breaks pte_present/pmd_present and the patch above exposed this > invariant breakage for pmd_present. > > The same problem already existed for the pte and pte_present and it > was fixed by commit 660a293ea9be709b893d371fbc0328fcca33c33a (if it > wasn't for that commit, it wouldn't even be a regression). That fix > avoids the pagefault to use pte_present. I could follow through by > stopping using pmd_present/pmd_huge too. > > However I think it's more robust to fix pageattr and to clear the > PSE/GLOBAL bitflags too in addition to the present bitflag. So the > kernel page fault can keep using the regular > pte_present/pmd_present/pmd_huge. > > The confusion arises because _PAGE_GLOBAL and _PAGE_PROTNONE are > sharing the same bit, and in the pmd case we pretend _PAGE_PSE to be > set only in present pmds (to facilitate split_huge_page final tlb > flush). > > Andrea Arcangeli (2): > Revert "x86, mm: Make spurious_fault check explicitly check the > PRESENT bit" > pageattr: prevent PSE and GLOABL leftovers to confuse pmd/pte_present > and pmd_huge > > arch/x86/mm/fault.c | 8 +------ > arch/x86/mm/pageattr.c | 50 +++++++++++++++++++++++++++++++++++++++++++++-- > 2 files changed, 48 insertions(+), 10 deletions(-) > > -- > 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 -- 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