From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758699Ab3BZXkY (ORCPT ); Tue, 26 Feb 2013 18:40:24 -0500 Received: from terminus.zytor.com ([198.137.202.10]:47806 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756234Ab3BZXkX (ORCPT ); Tue, 26 Feb 2013 18:40:23 -0500 Message-ID: <512D478C.4030503@zytor.com> Date: Tue, 26 Feb 2013 15:38:52 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130219 Thunderbird/17.0.3 MIME-Version: 1.0 To: Boris Ostrovsky CC: tglx@linutronix.de, mingo@redhat.com, konrad.wilk@oracle.com, xen-devel@lists.xen.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/x86: Flush lazy MMU when DEBUG_PAGEALLOC is set References: <1361919370-18058-1-git-send-email-boris.ostrovsky@oracle.com> In-Reply-To: <1361919370-18058-1-git-send-email-boris.ostrovsky@oracle.com> X-Enigmail-Version: 1.5 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/26/2013 02:56 PM, Boris Ostrovsky wrote: > When CONFIG_DEBUG_PAGEALLOC is set page table updates made by > kernel_map_pages() are not made visible (via TLB flush) immediately if lazy > MMU is on. In environments that support lazy MMU (e.g. Xen) this may lead to > fatal page faults, for example, when zap_pte_range() needs to allocate pages > in __tlb_remove_page() -> tlb_next_batch(). > > Signed-off-by: Boris Ostrovsky > --- > arch/x86/mm/pageattr.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index ca1f1c2..7b3216e 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -1369,6 +1369,8 @@ void kernel_map_pages(struct page *page, int numpages, int enable) > * but that can deadlock->flush only current cpu: > */ > __flush_tlb_all(); > + > + arch_flush_lazy_mmu_mode(); > } > > #ifdef CONFIG_HIBERNATION > This sounds like a critical fix, i.e. a -stable candidate. Am I correct? -hpa