HWPOISON: limit hwpoison injector to known page types

[sfrench/cifs-2.6.git] / mm / hwpoison-inject.c

diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index e1d85137f0864ba459609f8b26b0a95ffc97eedd..2b6b3200fa65fd5a4b154d4b9717e1d459905e02 100644 (file)
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -3,18 +3,65 @@
 #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, *corrupt_pfn;
+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)
+{
+       if (!capable(CAP_SYS_ADMIN))
+               return -EPERM;
+
+       return unpoison_memory(val);
 }
 
 DEFINE_SIMPLE_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
+DEFINE_SIMPLE_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");
 
 static void pfn_inject_exit(void)
 {
@@ -24,16 +71,41 @@ static void pfn_inject_exit(void)
 
 static int pfn_inject_init(void)
 {
+       struct dentry *dentry;
+
        hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
        if (hwpoison_dir == NULL)
                return -ENOMEM;
-       corrupt_pfn = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
+
+       /*
+        * Note that the below poison/unpoison interfaces do not involve
+        * hardware status change, hence do not require hardware support.
+        * They are mainly for testing hwpoison in software level.
+        */
+       dentry = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
                                          NULL, &hwpoison_fops);
-       if (corrupt_pfn == NULL) {
-               pfn_inject_exit();
-               return -ENOMEM;
-       }
+       if (!dentry)
+               goto fail;
+
+       dentry = debugfs_create_file("unpoison-pfn", 0600, hwpoison_dir,
+                                    NULL, &unpoison_fops);
+       if (!dentry)
+               goto fail;
+
+       dentry = debugfs_create_u32("corrupt-filter-dev-major", 0600,
+                                   hwpoison_dir, &hwpoison_filter_dev_major);
+       if (!dentry)
+               goto fail;
+
+       dentry = debugfs_create_u32("corrupt-filter-dev-minor", 0600,
+                                   hwpoison_dir, &hwpoison_filter_dev_minor);
+       if (!dentry)
+               goto fail;
+
        return 0;
+fail:
+       pfn_inject_exit();
+       return -ENOMEM;
 }
 
 module_init(pfn_inject_init);