From: Zefan Li <lize...@huawei.com>
3.4.113-rc1 review patch. If anyone has any objections, please let me know.
------------------
Signed-off-by: Zefan Li <lize...@huawei.com>
---
mm/hugetlb.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 416cbfd..6726bfe 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2929,13 +2929,17 @@ out_page_table_lock:
unlock_page(pagecache_page);
put_page(pagecache_page);
}
- if (page != pagecache_page)
- unlock_page(page);
- put_page(page);
-
out_mutex:
mutex_unlock(&hugetlb_instantiation_mutex);
-
+ /*
+ * Generally it's safe to hold refcount during waiting page lock. But
+ * here we just wait to defer the next page fault to avoid busy loop and
+ * the page is not used after unlocked before returning from the current
+ * page fault. So we are safe from accessing freed page, even if we wait
+ * here without taking refcount.
+ */
+ if (need_wait_lock)
+ wait_on_page_locked(page);
return ret;
}
--
1.9.1
