From 08259d58e4fa12ceaece82193c5816152f638cca Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Fri, 5 Mar 2010 13:42:25 -0800 Subject: [PATCH] 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 Reported-by: Huang Shijie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/swapfile.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) 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) {