From 76fef140a395cfceb7d6595249f77333a4b0c0af Mon Sep 17 00:00:00 2001
From: Wu Fengguang <fengguang.wu@intel.com>
Date: Wed, 16 Dec 2009 12:19:59 +0100
Subject: [PATCH] --- yaml --- r: 177627 b: refs/heads/master c:
 31d3d3484f9bd263925ecaa341500ac2df3a5d9b h: refs/heads/master i:   177625:
 cac2a114419c02583ababfe53d1078c9cc9085be   177623:
 2ec5357f2241e9378ceb17a983a97da7c2a12611 v: v3

---
 [refs]                              |  2 +-
 trunk/Documentation/vm/hwpoison.txt |  3 ++-
 trunk/mm/hwpoison-inject.c          | 41 +++++++++++++++++++++++++++--
 trunk/mm/internal.h                 |  2 ++
 4 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 9d02c849a199..13b28db28423 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 7c116f2b0dbac4a1dd051c7a5e8cef37701cafd4
+refs/heads/master: 31d3d3484f9bd263925ecaa341500ac2df3a5d9b
diff --git a/trunk/Documentation/vm/hwpoison.txt b/trunk/Documentation/vm/hwpoison.txt
index fdf580464324..4ef7bb30d15c 100644
--- a/trunk/Documentation/vm/hwpoison.txt
+++ b/trunk/Documentation/vm/hwpoison.txt
@@ -103,7 +103,8 @@ hwpoison-inject module through debugfs
 
 corrupt-pfn
 
-Inject hwpoison fault at PFN echoed into this file.
+Inject hwpoison fault at PFN echoed into this file. This does
+some early filtering to avoid corrupted unintended pages in test suites.
 
 unpoison-pfn
 
diff --git a/trunk/mm/hwpoison-inject.c b/trunk/mm/hwpoison-inject.c
index ac692a9b766c..2b6b3200fa65 100644
--- a/trunk/mm/hwpoison-inject.c
+++ b/trunk/mm/hwpoison-inject.c
@@ -3,16 +3,53 @@
 #include <linux/debugfs.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
 #include "internal.h"
 
 static struct dentry *hwpoison_dir;
 
 static int hwpoison_inject(void *data, u64 val)
 {
+	unsigned long pfn = val;
+	struct page *p;
+	int err;
+
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
-	printk(KERN_INFO "Injecting memory failure at pfn %Lx\n", val);
-	return __memory_failure(val, 18, 0);
+
+	if (!pfn_valid(pfn))
+		return -ENXIO;
+
+	p = pfn_to_page(pfn);
+	/*
+	 * This implies unable to support free buddy pages.
+	 */
+	if (!get_page_unless_zero(p))
+		return 0;
+
+	if (!PageLRU(p))
+		shake_page(p);
+	/*
+	 * This implies unable to support non-LRU pages.
+	 */
+	if (!PageLRU(p))
+		return 0;
+
+	/*
+	 * 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).
+	 * We temporarily take page lock for try_get_mem_cgroup_from_page().
+	 * __memory_failure() will redo the check reliably inside page lock.
+	 */
+	lock_page(p);
+	err = hwpoison_filter(p);
+	unlock_page(p);
+	if (err)
+		return 0;
+
+	printk(KERN_INFO "Injecting memory failure at pfn %lx\n", pfn);
+	return __memory_failure(pfn, 18, MF_COUNT_INCREASED);
 }
 
 static int hwpoison_unpoison(void *data, u64 val)
diff --git a/trunk/mm/internal.h b/trunk/mm/internal.h
index 814da335f050..04bbce8b8ba6 100644
--- a/trunk/mm/internal.h
+++ b/trunk/mm/internal.h
@@ -251,5 +251,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 #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;