From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: [PATCH 8/8] hwpoison: prevent /dev/kcore from accessing hwpoison pages Date: Wed, 13 Jan 2010 21:53:13 +0800 Message-ID: <20100113135958.291404947@intel.com> References: <20100113135305.013124116@intel.com> Return-path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 5C8616B0071 for ; Wed, 13 Jan 2010 09:00:35 -0500 (EST) Content-Disposition: inline; filename=hwpoison-kcore.patch Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Wu Fengguang , LKML , Ingo Molnar , Andi Kleen , Pekka Enberg , KAMEZAWA Hiroyuki , Nick Piggin , Hugh Dickins , Linux Memory Management List List-Id: linux-mm.kvack.org Silently fill buffer with zeros when encounter hwpoison pages (accessing the hwpoison page content is deadly). This patch does not cover X86_32 - which has a dumb kern_addr_valid(). It is unlikely anyone run a 32bit kernel will care about the hwpoison feature - its usable memory is limited. CC: Ingo Molnar CC: Andi Kleen CC: Pekka Enberg Signed-off-by: Wu Fengguang --- arch/x86/mm/init_64.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- linux-mm.orig/arch/x86/mm/init_64.c 2010-01-13 21:23:04.000000000 +0800 +++ linux-mm/arch/x86/mm/init_64.c 2010-01-13 21:25:32.000000000 +0800 @@ -825,6 +825,7 @@ int __init reserve_bootmem_generic(unsig int kern_addr_valid(unsigned long addr) { unsigned long above = ((long)addr) >> __VIRTUAL_MASK_SHIFT; + unsigned long pfn; pgd_t *pgd; pud_t *pud; pmd_t *pmd; @@ -845,14 +846,23 @@ int kern_addr_valid(unsigned long addr) if (pmd_none(*pmd)) return 0; - if (pmd_large(*pmd)) - return pfn_valid(pmd_pfn(*pmd)); + if (pmd_large(*pmd)) { + pfn = pmd_pfn(*pmd); + pfn += pte_index(addr); + goto check_pfn; + } pte = pte_offset_kernel(pmd, addr); if (pte_none(*pte)) return 0; - return pfn_valid(pte_pfn(*pte)); + pfn = pte_pfn(*pte); +check_pfn: + if (!pfn_valid(pfn)) + return 0; + if (PageHWPoison(pfn_to_page(pfn))) + return 0; + return 1; } /* -- 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