From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751526AbaJBTnS (ORCPT ); Thu, 2 Oct 2014 15:43:18 -0400 Received: from mail-ob0-f169.google.com ([209.85.214.169]:37286 "EHLO mail-ob0-f169.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750945AbaJBTnR (ORCPT ); Thu, 2 Oct 2014 15:43:17 -0400 Date: Thu, 2 Oct 2014 12:41:30 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@eggly.anvils To: Mel Gorman cc: Andrew Morton , Rik van Riel , Peter Zijlstra , Hugh Dickins , Linux Kernel , linux-mm@kvack.org Subject: Re: [PATCH] mm: mempolicy: Skip inaccessible VMAs when setting MPOL_MF_LAZY In-Reply-To: <20141002191703.GN17501@suse.de> Message-ID: References: <20141002191703.GN17501@suse.de> User-Agent: Alpine 2.11 (LSU 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2 Oct 2014, Mel Gorman wrote: > PROT_NUMA VMAs are skipped to avoid problems distinguishing between > present, prot_none and special entries. MPOL_MF_LAZY is not visible from > userspace since commit a720094ded8c ("mm: mempolicy: Hide MPOL_NOOP and > MPOL_MF_LAZY from userspace for now") but it should still skip VMAs the > same way task_numa_work does. > > Signed-off-by: Mel Gorman > Acked-by: Rik van Riel Acked-by: Hugh Dickins Yes, this is much the same as the patch I wrote for Linus two days ago, then discovered that we don't need until MPOL_MF_LAZY gets brought back into MPOL_MF_VALID. (As a bonus, my patch did also remove the currently bogus paragraph of comment above change_prot_numa(); and I would prefer a code comment to make clear that we never exercise this path at present.) > --- > mm/mempolicy.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index 8f5330d..a5877ce 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -683,7 +683,9 @@ queue_pages_range(struct mm_struct *mm, unsigned long start, unsigned long end, > } > > if (flags & MPOL_MF_LAZY) { > - change_prot_numa(vma, start, endvma); > + /* Similar to task_numa_work, skip inaccessible VMAs */ > + if (vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE)) > + change_prot_numa(vma, start, endvma); > goto next; > } >