From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: [PATCH 16/24] HWPOISON: limit hwpoison injector to known page types Date: Wed, 02 Dec 2009 11:12:47 +0800 Message-ID: <20091202043045.711553780@intel.com> References: <20091202031231.735876003@intel.com> Return-path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 7973C6007B8 for ; Tue, 1 Dec 2009 23:37:38 -0500 (EST) Content-Disposition: inline; filename=hwpoison-filter-limit-scope.patch Sender: owner-linux-mm@kvack.org To: Andi Kleen Cc: Andrew Morton , Haicheng Li , Wu Fengguang , Nick Piggin , linux-mm@kvack.org, LKML List-Id: linux-mm.kvack.org __memory_failure()'s workflow is set PG_hwpoison //... unset PG_hwpoison if didn't pass hwpoison filter That could kill unrelated process if it happens to page fault on the page with the (temporary) PG_hwpoison. The race should be big enough to appear in stress tests. Fix it by grabbing the page and checking filter at inject time. This also avoids the very noisy "Injecting memory failure..." messages. - we don't touch madvise() based injection, because the filters are generally not necessary for it. - if we want to apply the filters to h/w aided injection, we'd better to rearrange the logic in __memory_failure() instead of this patch. CC: Haicheng Li CC: Andi Kleen Signed-off-by: Wu Fengguang --- mm/hwpoison-inject.c | 27 ++++++++++++++++++++++++++- mm/internal.h | 2 ++ 2 files changed, 28 insertions(+), 1 deletion(-) --- linux-mm.orig/mm/hwpoison-inject.c 2009-11-30 20:44:41.000000000 +0800 +++ linux-mm/mm/hwpoison-inject.c 2009-11-30 20:58:20.000000000 +0800 @@ -3,16 +3,41 @@ #include #include #include +#include #include "internal.h" static struct dentry *hwpoison_dir; static int hwpoison_inject(void *data, u64 val) { + unsigned long pfn = val; + struct page *p; + if (!capable(CAP_SYS_ADMIN)) return -EPERM; + + if (!pfn_valid(pfn)) + return -ENXIO; + + /* + * This implies unable to support free buddy pages. + */ + p = pfn_to_page(pfn); + if (!get_page_unless_zero(p)) + return 0; + + if (!PageLRU(p)) + lru_add_drain_all(); + /* + * do a racy check with elevated page count, to make sure PG_hwpoison + * will only be set for the targeted owner (or on a free page). + * __memory_failure() will redo the check reliably inside page lock. + */ + if (hwpoison_filter(p)) + return 0; + printk(KERN_INFO "Injecting memory failure at pfn %Lx\n", val); - return __memory_failure(val, 18, 0); + return __memory_failure(val, 18, 1); } static int hwpoison_forget(void *data, u64 val) --- linux-mm.orig/mm/internal.h 2009-11-30 20:44:41.000000000 +0800 +++ linux-mm/mm/internal.h 2009-11-30 20:52:11.000000000 +0800 @@ -264,5 +264,7 @@ int __get_user_pages(struct task_struct #define ZONE_RECLAIM_SUCCESS 1 #endif +extern int hwpoison_filter(struct page *p); + extern u32 hwpoison_filter_dev_major; extern u32 hwpoison_filter_dev_minor; -- 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