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authorPaul Cassella <cassella@cray.com>2014-08-07 03:07:24 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-07 05:01:20 +0400
commit9a95f3cf7b33d66fa64727cff8cd2f2a9d09f335 (patch)
tree14d7c178144b6de0b352b8e8d4b04ffdbae9a71c /include/linux/pagemap.h
parent4ffeaf3560a52b4a69cc7909873d08c0ef5909d4 (diff)
downloadlinux-9a95f3cf7b33d66fa64727cff8cd2f2a9d09f335.tar.xz
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 <cassella@cray.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/pagemap.h')
-rw-r--r--include/linux/pagemap.h3
1 files changed, 3 insertions, 0 deletions
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)