3 files changed, 43 insertions, 3 deletions

diff --git a/Documentation/vm/hwpoison.txt b/Documentation/vm/hwpoison.txt
index fdf580464324..4ef7bb30d15c 100644
--- a/Documentation/vm/hwpoison.txt
+++ b/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/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index ac692a9b766c..2b6b3200fa65 100644
--- a/mm/hwpoison-inject.c
+++ b/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/mm/internal.h b/mm/internal.h
index 814da335f050..04bbce8b8ba6 100644
--- a/mm/internal.h
+++ b/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;