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   1 /* Inject a hwpoison memory failure on a arbitary pfn */
   2 #include <linux/module.h>
   3 #include <linux/debugfs.h>
   4 #include <linux/kernel.h>
   5 #include <linux/mm.h>
   6 #include <linux/swap.h>
   7 #include <linux/pagemap.h>
   8 #include "internal.h"
   9
  10 static struct dentry *hwpoison_dir;
  11
  12 static int hwpoison_inject(void *data, u64 val)
  13 {
  14         unsigned long pfn = val;
  15         struct page *p;
  16         int err;
  17
  18         if (!capable(CAP_SYS_ADMIN))
  19                 return -EPERM;
  20
  21         if (!pfn_valid(pfn))
  22                 return -ENXIO;
  23
  24         p = pfn_to_page(pfn);
  25         /*
  26          * This implies unable to support free buddy pages.
  27          */
  28         if (!get_page_unless_zero(p))
  29                 return 0;
  30
  31         if (!PageLRU(p))
  32                 shake_page(p);
  33         /*
  34          * This implies unable to support non-LRU pages.
  35          */
  36         if (!PageLRU(p))
  37                 return 0;
  38
  39         /*
  40          * do a racy check with elevated page count, to make sure PG_hwpoison
  41          * will only be set for the targeted owner (or on a free page).
  42          * We temporarily take page lock for try_get_mem_cgroup_from_page().
  43          * __memory_failure() will redo the check reliably inside page lock.
  44          */
  45         lock_page(p);
  46         err = hwpoison_filter(p);
  47         unlock_page(p);
  48         if (err)
  49                 return 0;
  50
  51         printk(KERN_INFO "Injecting memory failure at pfn %lx\n", pfn);
  52         return __memory_failure(pfn, 18, MF_COUNT_INCREASED);
  53 }
  54
  55 static int hwpoison_unpoison(void *data, u64 val)
  56 {
  57         if (!capable(CAP_SYS_ADMIN))
  58                 return -EPERM;
  59
  60         return unpoison_memory(val);
  61 }
  62
  63 DEFINE_SIMPLE_ATTRIBUTE(hwpoison_fops, NULL, hwpoison_inject, "%lli\n");
  64 DEFINE_SIMPLE_ATTRIBUTE(unpoison_fops, NULL, hwpoison_unpoison, "%lli\n");
  65
  66 static void pfn_inject_exit(void)
  67 {
  68         if (hwpoison_dir)
  69                 debugfs_remove_recursive(hwpoison_dir);
  70 }
  71
  72 static int pfn_inject_init(void)
  73 {
  74         struct dentry *dentry;
  75
  76         hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
  77         if (hwpoison_dir == NULL)
  78                 return -ENOMEM;
  79
  80         /*
  81          * Note that the below poison/unpoison interfaces do not involve
  82          * hardware status change, hence do not require hardware support.
  83          * They are mainly for testing hwpoison in software level.
  84          */
  85         dentry = debugfs_create_file("corrupt-pfn", 0600, hwpoison_dir,
  86                                           NULL, &hwpoison_fops);
  87         if (!dentry)
  88                 goto fail;
  89
  90         dentry = debugfs_create_file("unpoison-pfn", 0600, hwpoison_dir,
  91                                      NULL, &unpoison_fops);
  92         if (!dentry)
  93                 goto fail;
  94
  95         dentry = debugfs_create_u32("corrupt-filter-enable", 0600,
  96                                     hwpoison_dir, &hwpoison_filter_enable);
  97         if (!dentry)
  98                 goto fail;
  99
 100         dentry = debugfs_create_u32("corrupt-filter-dev-major", 0600,
 101                                     hwpoison_dir, &hwpoison_filter_dev_major);
 102         if (!dentry)
 103                 goto fail;
 104
 105         dentry = debugfs_create_u32("corrupt-filter-dev-minor", 0600,
 106                                     hwpoison_dir, &hwpoison_filter_dev_minor);
 107         if (!dentry)
 108                 goto fail;
 109
 110         dentry = debugfs_create_u64("corrupt-filter-flags-mask", 0600,
 111                                     hwpoison_dir, &hwpoison_filter_flags_mask);
 112         if (!dentry)
 113                 goto fail;
 114
 115         dentry = debugfs_create_u64("corrupt-filter-flags-value", 0600,
 116                                     hwpoison_dir, &hwpoison_filter_flags_value);
 117         if (!dentry)
 118                 goto fail;
 119
 120 #ifdef  CONFIG_CGROUP_MEM_RES_CTLR_SWAP
 121         dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
 122                                     hwpoison_dir, &hwpoison_filter_memcg);
 123         if (!dentry)
 124                 goto fail;
 125 #endif
 126
 127         return 0;
 128 fail:
 129         pfn_inject_exit();
 130         return -ENOMEM;
 131 }
 132
 133 module_init(pfn_inject_init);
 134 module_exit(pfn_inject_exit);
 135 MODULE_LICENSE("GPL");