From 9a95f3cf7b33d66fa64727cff8cd2f2a9d09f335 Mon Sep 17 00:00:00 2001 From: Paul Cassella Date: Wed, 6 Aug 2014 16:07:24 -0700 Subject: mm: describe mmap_sem rules for __lock_page_or_retry() and callers Add a comment describing the circumstances in which __lock_page_or_retry() will or will not release the mmap_sem when returning 0. Add comments to lock_page_or_retry()'s callers (filemap_fault(), do_swap_page()) noting the impact on VM_FAULT_RETRY returns. Add comments on up the call tree, particularly replacing the false "We return with mmap_sem still held" comments. Signed-off-by: Paul Cassella Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/pagemap.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include') diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index e1474ae18c88..3df8c7db7a4e 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -484,6 +484,9 @@ static inline int lock_page_killable(struct page *page) /* * lock_page_or_retry - Lock the page, unless this would block and the * caller indicated that it can handle a retry. + * + * Return value and mmap_sem implications depend on flags; see + * __lock_page_or_retry(). */ static inline int lock_page_or_retry(struct page *page, struct mm_struct *mm, unsigned int flags) -- cgit v1.2.3