mm: hwpoison: call shake_page() unconditionally

shake_page() is called before going into core error handling code in
order to ensure that the error page is flushed from lru_cache lists
where pages stay during transferring among LRU lists.

But currently it's not fully functional because when the page is linked
to lru_cache by calling activate_page(), its PageLRU flag is set and
shake_page() is skipped.  The result is to fail error handling with
"still referenced by 1 users" message.

When the page is linked to lru_cache by isolate_lru_page(), its PageLRU
is clear, so that's fine.

This patch makes shake_page() unconditionally called to avoild the
failure.

Fixes: 23a003bf ("mm/madvise: pass return code of memory_failure() to userspace")
Link: http://lkml.kernel.org/r/20170417055948.GM31394@yexl-desktop
Link: http://lkml.kernel.org/r/1493197841-23986-2-git-send-email-n-horiguchi@ah.jp.nec.comSigned-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Xiaolong Ye <xiaolong.ye@intel.com>
Cc: Chen Gong <gong.chen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/hwpoison-inject.c

@@ -34,7 +34,6 @@ static int hwpoison_inject(void *data, u64 val)
 	if (!hwpoison_filter_enable)
 		goto inject;
 
-	if (!PageLRU(hpage) && !PageHuge(p))
 	shake_page(hpage, 0);
 	/*
 	 * This implies unable to support non-LRU pages.

mm/memory-failure.c

@@ -220,6 +220,9 @@ static int kill_proc(struct task_struct *t, unsigned long addr, int trapno,
  */
 void shake_page(struct page *p, int access)
 {
+	if (PageHuge(p))
+		return;
+
 	if (!PageSlab(p)) {
 		lru_add_drain_all();
 		if (PageLRU(p))
@@ -1137,23 +1140,15 @@ int memory_failure(unsigned long pfn, int trapno, int flags)
 	 * The check (unnecessarily) ignores LRU pages being isolated and
 	 * walked by the page reclaim code, however that's not a big loss.
 	 */
-	if (!PageHuge(p)) {
-		if (!PageLRU(p))
 	shake_page(p, 0);
-		if (!PageLRU(p)) {
-			/*
-			 * shake_page could have turned it free.
-			 */
-			if (is_free_buddy_page(p)) {
+	/* shake_page could have turned it free. */
+	if (!PageLRU(p) && is_free_buddy_page(p)) {
 		if (flags & MF_COUNT_INCREASED)
 			action_result(pfn, MF_MSG_BUDDY, MF_DELAYED);
 		else
-					action_result(pfn, MF_MSG_BUDDY_2ND,
-						      MF_DELAYED);
+			action_result(pfn, MF_MSG_BUDDY_2ND, MF_DELAYED);
 		return 0;
 	}
-		}
-	}
 
 	lock_page(hpage);