From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ee0-f53.google.com (mail-ee0-f53.google.com [74.125.83.53]) by kanga.kvack.org (Postfix) with ESMTP id B15CE6B0082 for ; Tue, 3 Dec 2013 18:46:41 -0500 (EST) Received: by mail-ee0-f53.google.com with SMTP id b57so1900054eek.26 for ; Tue, 03 Dec 2013 15:46:41 -0800 (PST) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTP id o46si4687415eef.107.2013.12.03.15.46.40 for ; Tue, 03 Dec 2013 15:46:40 -0800 (PST) Date: Tue, 3 Dec 2013 23:46:37 +0000 From: Mel Gorman Subject: Re: [PATCH 14/15] mm: numa: Flush TLB if NUMA hinting faults race with PTE scan update Message-ID: <20131203234637.GS11295@suse.de> References: <1386060721-3794-1-git-send-email-mgorman@suse.de> <1386060721-3794-15-git-send-email-mgorman@suse.de> <529E641A.7040804@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <529E641A.7040804@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Rik van Riel Cc: Alex Thorlton , Linux-MM , LKML On Tue, Dec 03, 2013 at 06:07:06PM -0500, Rik van Riel wrote: > On 12/03/2013 03:52 AM, Mel Gorman wrote: > > NUMA PTE updates and NUMA PTE hinting faults can race against each other. The > > setting of the NUMA bit defers the TLB flush to reduce overhead. NUMA > > hinting faults do not flush the TLB as X86 at least does not cache TLB > > entries for !present PTEs. However, in the event that the two race a NUMA > > hinting fault may return with the TLB in an inconsistent state between > > different processors. This patch detects potential for races between the > > NUMA PTE scanner and fault handler and will flush the TLB for the affected > > range if there is a race. > > > > Signed-off-by: Mel Gorman > > > diff --git a/mm/migrate.c b/mm/migrate.c > > index 5dfd552..ccc814b 100644 > > --- a/mm/migrate.c > > +++ b/mm/migrate.c > > @@ -1662,6 +1662,39 @@ void wait_migrate_huge_page(struct anon_vma *anon_vma, pmd_t *pmd) > > smp_rmb(); > > } > > > > +unsigned long numa_fault_prepare(struct mm_struct *mm) > > +{ > > + /* Paired with task_numa_work */ > > + smp_rmb(); > > + return mm->numa_next_reset; > > +} > > The patch that introduces mm->numa_next_reset, and the > patch that increments it, seem to be missing from your > series... > Damn. s/numa_next_reset/numa_next_scan/ in that patch -- Mel Gorman SUSE Labs -- 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