Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752843AbbKJNxJ (ORCPT ); Tue, 10 Nov 2015 08:53:09 -0500 Received: from mail-wm0-f41.google.com ([74.125.82.41]:36011 "EHLO mail-wm0-f41.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751998AbbKJNxH (ORCPT ); Tue, 10 Nov 2015 08:53:07 -0500 Date: Tue, 10 Nov 2015 15:53:03 +0200 From: "Kirill A. Shutemov" To: Borislav Petkov Cc: "Kirill A. Shutemov" , hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, akpm@linux-foundation.org, 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, Toshi Kani Subject: Re: [PATCH] x86/mm: fix regression with huge pages on PAE Message-ID: <20151110135303.GA11246@node.shutemov.name> References: <1447111090-8526-1-git-send-email-kirill.shutemov@linux.intel.com> <20151110123429.GE19187@pd.tnic> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20151110123429.GE19187@pd.tnic> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2662 Lines: 57 On Tue, Nov 10, 2015 at 01:34:29PM +0100, Borislav Petkov wrote: > On Tue, Nov 10, 2015 at 01:18:10AM +0200, Kirill A. Shutemov wrote: > > 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; > > In file included from ./arch/x86/include/asm/boot.h:5:0, > from ./arch/x86/boot/boot.h:26, > from arch/x86/realmode/rm/wakemain.c:2: > ./arch/x86/include/asm/pgtable_types.h: In function ‘pud_pfn_mask’: > ./arch/x86/include/asm/pgtable_types.h:282:10: warning: large integer implicitly truncated to unsigned type [-Woverflow] > return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK; > ^ > ./arch/x86/include/asm/pgtable_types.h: In function ‘pmd_pfn_mask’: > ./arch/x86/include/asm/pgtable_types.h:300:10: warning: large integer implicitly truncated to unsigned type [-Woverflow] > return ~((1ULL << PMD_SHIFT) - 1) & PHYSICAL_PAGE_MASK; > ^ > In file included from ./arch/x86/include/asm/boot.h:5:0, > from arch/x86/realmode/rm/../../boot/boot.h:26, > from arch/x86/realmode/rm/../../boot/video-mode.c:18, > from arch/x86/realmode/rm/video-mode.c:1: > ./arch/x86/include/asm/pgtable_types.h: In function ‘pud_pfn_mask’: > ./arch/x86/include/asm/pgtable_types.h:282:10: warning: large integer implicitly truncated to unsigned type [-Woverflow] > return ~((1ULL << PUD_SHIFT) - 1) & PHYSICAL_PAGE_MASK; > ^ > ... > > That's a 64-bit config. Oh.. pmdval_t/pudval_t is 'unsinged long' on 64 bit. But realmode code uses -m16 which makes 'unsigned long' 32-bit therefore truncation warning. These helpers not really used in realmode code. I see few ways out: - convert helpers to macros to avoid their translation; - wrap the code into not-for-realmode ifdef. (Do we have any?); - convert pudval_t/pmdval_t to u64 for 64-bit. I'm not sure what side effects would it have. Any opinions? -- Kirill A. Shutemov -- 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/