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