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| author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2010-03-05 13:42:25 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-03-06 11:26:27 -0800 |
| commit | 08259d58e4fa12ceaece82193c5816152f638cca (patch) | |
| tree | 8c032914139c5aec362a73b8316cf81f020f9f8f | |
| parent | c08c6e1f54c85fc299cf9f88cf330d6dd28a9a1d (diff) | |
| download | lwn-08259d58e4fa12ceaece82193c5816152f638cca.tar.gz lwn-08259d58e4fa12ceaece82193c5816152f638cca.zip | |
mm: add comment on swap_duplicate's error code
swap_duplicate()'s loop appears to miss out on returning the error code
from __swap_duplicate(), except when that's -ENOMEM. In fact this is
intentional: prior to -ENOMEM for swap_count_continuation,
swap_duplicate() was void (and the case only occurs when copy_one_pte()
hits a corrupt pte). But that's surprising behaviour, which certainly
deserves a comment.
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/swapfile.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 4a986127f15e..84374d8cf814 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -2161,7 +2161,11 @@ void swap_shmem_alloc(swp_entry_t entry) } /* - * increase reference count of swap entry by 1. + * Increase reference count of swap entry by 1. + * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required + * but could not be atomically allocated. Returns 0, just as if it succeeded, + * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which + * might occur if a page table entry has got corrupted. */ int swap_duplicate(swp_entry_t entry) { |