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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>
This commit is contained in:
Hugh Dickins 2010-03-05 13:42:25 -08:00 committed by Linus Torvalds
parent c08c6e1f54
commit 08259d58e4
1 changed files with 5 additions and 1 deletions
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6
mm/swapfile.c
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@ -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)
{