[PATCH v2 3/5] mm/memory-failure.c: add hwpoison_filter for soft offline

[zhenwei pi <pizhenwei@bytedance.com>]

hwpoison_filter is missing in the soft offline path, this leads an
issue: after enabling the corrupt filter, the user process still has
a chance to inject hwpoison fault by
madvise(addr, len, MADV_SOFT_OFFLINE) at PFN which is expected to
reject.

Also do a minor change in comment of memory_failure().

Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
---
 mm/memory-failure.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index ece05858568f..ed280ef5473d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1762,7 +1762,7 @@ static DEFINE_MUTEX(mf_mutex);
  * enabled and no spinlocks hold.
  *
  * Return: 0 for successfully handled the memory error,
- *         -EOPNOTSUPP for memory_filter() filtered the error event,
+ *         -EOPNOTSUPP for hwpoison_filter() filtered the error event,
  *         < 0(except -EOPNOTSUPP) on failure.
  */
 int memory_failure(unsigned long pfn, int flags)
@@ -2317,7 +2317,9 @@ static void put_ref_page(struct page *page)
  * @pfn: pfn to soft-offline
  * @flags: flags. Same as memory_failure().
  *
- * Returns 0 on success, otherwise negated errno.
+ * Returns 0 on success
+ *         -EOPNOTSUPP for hwpoison_filter() filtered the error event
+ *         < 0 otherwise negated errno.
  *
  * Soft offline a page, by migration or invalidation,
  * without killing anything. This is for the case when
@@ -2368,6 +2370,16 @@ int soft_offline_page(unsigned long pfn, int flags)
 	ret = get_hwpoison_page(page, flags | MF_SOFT_OFFLINE);
 	put_online_mems();
 
+	if (hwpoison_filter(page)) {
+		if (ret > 0)
+			put_page(page);
+		else
+			put_ref_page(ref_page);
+
+		mutex_unlock(&mf_mutex);
+		return -EOPNOTSUPP;
+	}
+
 	if (ret > 0) {
 		ret = soft_offline_in_use_page(page);
 	} else if (ret == 0) {
-- 
2.20.1