v4.19.13 snapshot.
diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
new file mode 100644
index 0000000..b6ac706
--- /dev/null
+++ b/mm/hwpoison-inject.c
@@ -0,0 +1,140 @@
+/* Inject a hwpoison memory failure on a arbitrary pfn */
+#include <linux/module.h>
+#include <linux/debugfs.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/swap.h>
+#include <linux/pagemap.h>
+#include <linux/hugetlb.h>
+#include "internal.h"
+
+static struct dentry *hwpoison_dir;
+
+static int hwpoison_inject(void *data, u64 val)
+{
+ unsigned long pfn = val;
+ struct page *p;
+ struct page *hpage;
+ int err;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (!pfn_valid(pfn))
+ return -ENXIO;
+
+ p = pfn_to_page(pfn);
+ hpage = compound_head(p);
+ /*
+ * This implies unable to support free buddy pages.
+ */
+ if (!get_hwpoison_page(p))
+ return 0;
+
+ if (!hwpoison_filter_enable)
+ goto inject;
+
+ shake_page(hpage, 0);
+ /*
+ * This implies unable to support non-LRU pages.
+ */
+ if (!PageLRU(hpage) && !PageHuge(p))
+ goto put_out;
+
+ /*
+ * 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.
+ */
+ err = hwpoison_filter(hpage);
+ if (err)
+ goto put_out;
+
+inject:
+ pr_info("Injecting memory failure at pfn %#lx\n", pfn);
+ return memory_failure(pfn, MF_COUNT_INCREASED);
+put_out:
+ put_hwpoison_page(p);
+ return 0;
+}
+
+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)
+{
+ debugfs_remove_recursive(hwpoison_dir);
+}
+
+static int pfn_inject_init(void)
+{
+ struct dentry *dentry;
+
+ hwpoison_dir = debugfs_create_dir("hwpoison", NULL);
+ if (hwpoison_dir == NULL)
+ return -ENOMEM;
+
+ /*
+ * 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", 0200, hwpoison_dir,
+ NULL, &hwpoison_fops);
+ if (!dentry)
+ goto fail;
+
+ dentry = debugfs_create_file("unpoison-pfn", 0200, hwpoison_dir,
+ NULL, &unpoison_fops);
+ if (!dentry)
+ goto fail;
+
+ dentry = debugfs_create_u32("corrupt-filter-enable", 0600,
+ hwpoison_dir, &hwpoison_filter_enable);
+ 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;
+
+ dentry = debugfs_create_u64("corrupt-filter-flags-mask", 0600,
+ hwpoison_dir, &hwpoison_filter_flags_mask);
+ if (!dentry)
+ goto fail;
+
+ dentry = debugfs_create_u64("corrupt-filter-flags-value", 0600,
+ hwpoison_dir, &hwpoison_filter_flags_value);
+ if (!dentry)
+ goto fail;
+
+#ifdef CONFIG_MEMCG
+ dentry = debugfs_create_u64("corrupt-filter-memcg", 0600,
+ hwpoison_dir, &hwpoison_filter_memcg);
+ if (!dentry)
+ goto fail;
+#endif
+
+ return 0;
+fail:
+ pfn_inject_exit();
+ return -ENOMEM;
+}
+
+module_init(pfn_inject_init);
+module_exit(pfn_inject_exit);
+MODULE_LICENSE("GPL");