HWPOISON: add an interface to switch off/on all the page filters

In some use cases, user doesn't need extra filtering. E.g. user program
can inject errors through madvise syscall to its own pages, however it
might not know what the page state exactly is or which inode the page
belongs to.

So introduce an one-off interface "corrupt-filter-enable".

Echo 0 to switch off page filters, and echo 1 to switch on the filters.
[AK: changed default to 0]

Signed-off-by: Haicheng Li <haicheng.li@linux.intel.com>
Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

3 files changed, 11 insertions, 0 deletions

diff --git a/mm/hwpoison-inject.c b/mm/hwpoison-inject.c
index c838735ac31d..c597f46ac18a 100644
--- a/mm/hwpoison-inject.c
+++ b/mm/hwpoison-inject.c
@@ -92,6 +92,11 @@ static int pfn_inject_init(void)
         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)
diff --git a/mm/internal.h b/mm/internal.h
index 5a6761bea6a6..6a697bb97fc5 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -258,3 +258,4 @@ extern u32 hwpoison_filter_dev_minor;
 extern u64 hwpoison_filter_flags_mask;
 extern u64 hwpoison_filter_flags_value;
 extern u64 hwpoison_filter_memcg;
+extern u32 hwpoison_filter_enable;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 117ef1598469..2d5f1223bf4d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -49,10 +49,12 @@ int sysctl_memory_failure_recovery __read_mostly = 1;
 
 atomic_long_t mce_bad_pages __read_mostly = ATOMIC_LONG_INIT(0);
 
+u32 hwpoison_filter_enable = 0;
 u32 hwpoison_filter_dev_major = ~0U;
 u32 hwpoison_filter_dev_minor = ~0U;
 u64 hwpoison_filter_flags_mask;
 u64 hwpoison_filter_flags_value;
+EXPORT_SYMBOL_GPL(hwpoison_filter_enable);
 EXPORT_SYMBOL_GPL(hwpoison_filter_dev_major);
 EXPORT_SYMBOL_GPL(hwpoison_filter_dev_minor);
 EXPORT_SYMBOL_GPL(hwpoison_filter_flags_mask);
@@ -145,6 +147,9 @@ static int hwpoison_filter_task(struct page *p) { return 0; }
 
 int hwpoison_filter(struct page *p)
 {
+        if (!hwpoison_filter_enable)
+                return 0;
+
         if (hwpoison_filter_dev(p))
                 return -EINVAL;