Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753701AbbBSXJF (ORCPT ); Thu, 19 Feb 2015 18:09:05 -0500 Received: from mail-la0-f51.google.com ([209.85.215.51]:39836 "EHLO mail-la0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752308AbbBSXJD (ORCPT ); Thu, 19 Feb 2015 18:09:03 -0500 MIME-Version: 1.0 In-Reply-To: <54E5DFED.9050700@citrix.com> References: <54E5DFED.9050700@citrix.com> Date: Thu, 19 Feb 2015 15:09:01 -0800 X-Google-Sender-Auth: a6zT1AaffdXTz2fZGaIaDTmN1uU Message-ID: Subject: Re: NUMA_BALANCING and Xen PV guest regression in 3.20-rc0 From: Linus Torvalds To: David Vrabel Cc: Mel Gorman , "linux-kernel@vger.kernel.org" , "Xen-devel@lists.xen.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1030 Lines: 22 On Thu, Feb 19, 2015 at 5:06 AM, David Vrabel wrote: > > The NUMA_BALANCING series beginning with 5d833062139d (mm: numa: do not > dereference pmd outside of the lock during NUMA hinting fault) and > specifically 8a0516ed8b90 (mm: convert p[te|md]_numa users to > p[te|md]_protnone_numa) breaks Xen 64-bit PV guests. > > Any fault on a present userspace mapping (e.g., a write to a read-only > mapping) is being misinterpreted as a NUMA hinting fault and not handled > correctly. All userspace programs end up continuously faulting. > > This is because the hypervisor sets _PAGE_GLOBAL (== _PAGE_PROTNONE) on > all present userspace page table entries. That's some crazy stuff, but whatever. The patch is clearly good. Applied, Linus -- 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/