mm: replace some BUG_ONs by VM_BUG_ONs

The swap code is over-provisioned with BUG_ONs on assorted page flags,
mostly dating back to 2.3.  They're good documentation, and guard against
developer error, but a waste of space on most systems: change them to
VM_BUG_ONs, conditional on CONFIG_DEBUG_VM.  Just delete the PagePrivate
ones: they're later, from 2.5.69, but even less interesting now.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/mm/page_io.c b/mm/page_io.c
index 065c4480eaf0..d277a80efa71 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -125,8 +125,8 @@ int swap_readpage(struct file *file, struct page *page)
         struct bio *bio;
         int ret = 0;
 
-        BUG_ON(!PageLocked(page));
-        BUG_ON(PageUptodate(page));
+        VM_BUG_ON(!PageLocked(page));
+        VM_BUG_ON(PageUptodate(page));
         bio = get_swap_bio(GFP_KERNEL, page_private(page), page,
                                 end_swap_bio_read);
         if (bio == NULL) {