path: root/arch/x86
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authorPaul Cassella <cassella@cray.com>2014-08-06 16:07:24 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-08-06 18:01:20 -0700
commit9a95f3cf7b33d66fa64727cff8cd2f2a9d09f335 (patch)
tree14d7c178144b6de0b352b8e8d4b04ffdbae9a71c /arch/x86
parent4ffeaf3560a52b4a69cc7909873d08c0ef5909d4 (diff)
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 'arch/x86')
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 1dbade870f9..a2419468151 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1218,7 +1218,8 @@ good_area:
* If for any reason at all we couldn't handle the fault,
* make sure we exit gracefully rather than endlessly redo
- * the fault:
+ * the fault. Since we never set FAULT_FLAG_RETRY_NOWAIT, if
+ * we get VM_FAULT_RETRY back, the mmap_sem has been unlocked.
fault = handle_mm_fault(mm, vma, address, flags);