From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 267992808C6 for ; Thu, 9 Mar 2017 07:20:34 -0500 (EST) Received: by mail-wr0-f197.google.com with SMTP id u48so19527243wrc.0 for ; Thu, 09 Mar 2017 04:20:34 -0800 (PST) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id x19si8503692wrd.260.2017.03.09.04.20.32 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 09 Mar 2017 04:20:32 -0800 (PST) Date: Thu, 9 Mar 2017 13:20:30 +0100 From: Michal Hocko Subject: Re: [PATCH 6/7] mm: convert generic code to 5-level paging Message-ID: <20170309122030.GH11592@dhcp22.suse.cz> References: <20170306204514.1852-1-kirill.shutemov@linux.intel.com> <20170306204514.1852-7-kirill.shutemov@linux.intel.com> <20170308135734.GA11034@dhcp22.suse.cz> <20170308152129.sknp75d5usdu4vne@black.fi.intel.com> <20170309095415.GE11592@dhcp22.suse.cz> <20170309114716.e6ll7tsykz5iimnn@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170309114716.e6ll7tsykz5iimnn@node.shutemov.name> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: "Kirill A. Shutemov" , Linus Torvalds , Andrew Morton , x86@kernel.org, Thomas Gleixner , Ingo Molnar , Arnd Bergmann , "H. Peter Anvin" , Andi Kleen , Dave Hansen , Andy Lutomirski , linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org On Thu 09-03-17 14:47:16, Kirill A. Shutemov wrote: > On Thu, Mar 09, 2017 at 10:54:15AM +0100, Michal Hocko wrote: > > On Wed 08-03-17 18:21:30, Kirill A. Shutemov wrote: [...] > > > We can drop the hack once all architectures that support kasan would be > > > converted to pgtable-nop4d.h -- amd64 and x86 at the moment. > > > > But those architectures even do not enable kasan > > $ git grep "select *HAVE_ARCH_KASAN" > > arch/arm64/Kconfig: select HAVE_ARCH_KASAN if SPARSEMEM_VMEMMAP && !(ARM64_16K_PAGES && ARM64_VA_BITS_48) > > arch/x86/Kconfig: select HAVE_ARCH_KASAN if X86_64 && SPARSEMEM_VMEMMAP > > > > both arm64 and x86 (64b) do compile fine without the ifdef... So I guess > > we should be fine without it. > > Have you build the image to the final linking? lm_alias() hides the error > until later. > > x86-64 allmodconfig without the #ifndef: > > MODPOST vmlinux.o > mm/built-in.o: In function `kasan_populate_zero_shadow': > (.init.text+0xb72b): undefined reference to `kasan_zero_p4d' > Makefile:983: recipe for target 'vmlinux' failed > make: *** [vmlinux] Error 1 Interesting arm64 cross compile: $ grep CONFIG_KASAN .config CONFIG_KASAN=y CONFIG_KASAN_OUTLINE=y # CONFIG_KASAN_INLINE is not set Compiling for arm64 with aarch64-linux using gcc 4.9.0 [...] LD vmlinux.o MODPOST vmlinux.o KSYM .tmp_kallsyms1.o KSYM .tmp_kallsyms2.o LD vmlinux SORTEX vmlinux SYSMAP System.map x86_64 crosscompile with the same version to rule out gcc version changes $ grep CONFIG_KASAN .config CONFIG_KASAN_SHADOW_OFFSET=0xdffffc0000000000 CONFIG_KASAN=y CONFIG_KASAN_OUTLINE=y # CONFIG_KASAN_INLINE is not set [...] LD init/built-in.o LD vmlinux.o MODPOST vmlinux.o mm/built-in.o: In function `kasan_populate_zero_shadow': (.init.text+0x84e5): undefined reference to `kasan_zero_p4d' Makefile:983: recipe for target 'vmlinux' failed no idea why arm64 build was OK. Anyway I am not insisting on removing this ifdef it is just too ugly to spread __ARCH_HAS_5LEVEL_HACK outside of the arch code. We have few more in the mm code but those look much more understandable. Maybe a short comment explaining the ifdef would be better. Thanks! -- Michal Hocko 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