mm: memory-failure: fix unexpected return value in soft_offline_page()

When page_handle_poison() fails to handle the hugepage or free page in
retry path, soft_offline_page() will return 0 while -EBUSY is expected in
this case.

Consequently the user will think soft_offline_page succeeds while it in
fact failed.  So the user will not try again later in this case.

Link: https://lkml.kernel.org/r/20230627112808.1275241-1-linmiaohe@huawei.com
Fixes: b94e0282 ("mm,hwpoison: try to narrow window race for free pages")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/memory-failure.c

@@ -2741,11 +2741,14 @@ int soft_offline_page(unsigned long pfn, int flags)
 	if (ret > 0) {
 		ret = soft_offline_in_use_page(page);
 	} else if (ret == 0) {
-		if (!page_handle_poison(page, true, false) && try_again) {
+		if (!page_handle_poison(page, true, false)) {
+			if (try_again) {
 				try_again = false;
 				flags &= ~MF_COUNT_INCREASED;
 				goto retry;
 			}
+			ret = -EBUSY;
+		}
 	}
 
 	mutex_unlock(&mf_mutex);