diff options
| author | Paul Cassella <cassella@cray.com> | 2014-08-06 16:07:24 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-08-06 18:01:20 -0700 |
| commit | 9a95f3cf7b33d66fa64727cff8cd2f2a9d09f335 (patch) | |
| tree | 14d7c178144b6de0b352b8e8d4b04ffdbae9a71c /mm/mlock.c | |
| parent | 4ffeaf3560a52b4a69cc7909873d08c0ef5909d4 (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 'mm/mlock.c')
| -rw-r--r-- | mm/mlock.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/mm/mlock.c b/mm/mlock.c index b1eb53634005..ce84cb0b83ef 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -210,12 +210,19 @@ out: * @vma: target vma * @start: start address * @end: end address + * @nonblocking: * * This takes care of making the pages present too. * * return 0 on success, negative error code on error. * - * vma->vm_mm->mmap_sem must be held for at least read. + * vma->vm_mm->mmap_sem must be held. + * + * If @nonblocking is NULL, it may be held for read or write and will + * be unperturbed. + * + * If @nonblocking is non-NULL, it must held for read only and may be + * released. If it's released, *@nonblocking will be set to 0. */ long __mlock_vma_pages_range(struct vm_area_struct *vma, unsigned long start, unsigned long end, int *nonblocking) |