Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751512AbbKJAQ7 (ORCPT ); Mon, 9 Nov 2015 19:16:59 -0500 Received: from g9t1613g.houston.hp.com ([15.240.0.71]:36698 "EHLO g9t1613g.houston.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750863AbbKJAQ6 (ORCPT ); Mon, 9 Nov 2015 19:16:58 -0500 Message-ID: <1447114369.21443.37.camel@hpe.com> Subject: Re: [PATCH] x86/mm: fix regression with huge pages on PAE From: Toshi Kani To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, bp@alien8.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, jgross@suse.com, konrad.wilk@oracle.com, elliott@hpe.com, boris.ostrovsky@oracle.com Date: Mon, 09 Nov 2015 17:12:49 -0700 In-Reply-To: <20151109235728.GA7813@node.shutemov.name> References: <1447111090-8526-1-git-send-email-kirill.shutemov@linux.intel.com> <1447112591.21443.35.camel@hpe.com> <20151109235728.GA7813@node.shutemov.name> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.16.5 (3.16.5-3.fc22) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2504 Lines: 55 On Tue, 2015-11-10 at 01:57 +0200, Kirill A. Shutemov wrote: > On Mon, Nov 09, 2015 at 04:43:11PM -0700, Toshi Kani wrote: > > On Tue, 2015-11-10 at 01:18 +0200, Kirill A. Shutemov wrote: > > > Recent PAT patchset has caused issue on 32-bit PAE machines: > > : > > > The problem is in pmd_pfn_mask() and pmd_flags_mask(). These helpers use > > > PMD_PAGE_MASK to calculate resulting mask. PMD_PAGE_MASK is 'unsigned > > > long', not 'unsigned long long' as physaddr_t. As result upper bits of > > > resulting mask is truncated. > > > > > > The patch reworks code to use PMD_SHIFT as base of mask calculation > > > instead of PMD_PAGE_MASK. > > > > > > pud_pfn_mask() and pud_flags_mask() aren't problematic since we don't > > > have PUD page table level on 32-bit systems, but they reworked too to be > > > consistent with PMD counterpart. > > > > > > Signed-off-by: Kirill A. Shutemov > > > Reported-and-Tested-by: Boris Ostrovsky > > > Fixes: f70abb0fc3da ("x86/asm: Fix pud/pmd interfaces to handle large PAT > > > bit") > > > Cc: Toshi Kani > > > --- > > > arch/x86/include/asm/pgtable_types.h | 14 ++++---------- > > > 1 file changed, 4 insertions(+), 10 deletions(-) > > > > > > diff --git a/arch/x86/include/asm/pgtable_types.h > > > b/arch/x86/include/asm/pgtable_types.h > > > index dd5b0aa9dd2f..c1e797266ce9 100644 > > > --- a/arch/x86/include/asm/pgtable_types.h > > > +++ b/arch/x86/include/asm/pgtable_types.h > > > @@ -279,17 +279,14 @@ static inline pmdval_t native_pmd_val(pmd_t pmd) > > > static inline pudval_t pud_pfn_mask(pud_t pud) > > > { > > > if (native_pud_val(pud) & _PAGE_PSE) > > > - return PUD_PAGE_MASK & PHYSICAL_PAGE_MASK; > > > + return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK; > > > > Thanks for the fix! Should we fix the PMD/PUD MASK/SIZE macros, so that we > > do not hit the same issue again when they are used? > > I don't this so. PAGE_SIZE is not 'unsigned long long'. And all *PAGE_MASK > are usually applied to virtual addresses which are 'unsigned long'. > I think it's safer to leave them as they are. Thanks for the explanation! That makes sense. Reviewed-by: Toshi Kani -Toshi -- 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/