bug: completely remove code generated by disabled VM_BUG_ON()

bug: completely remove code generated by disabled VM_BUG_ON()

Even if CONFIG_DEBUG_VM=n gcc genereates code for some VM_BUG_ON()

for example VM_BUG_ON(!PageCompound(page) || !PageHead(page)); in
do_huge_pmd_wp_page() generates 114 bytes of code.

But they mostly disappears when I split this VM_BUG_ON into two:

  -VM_BUG_ON(!PageCompound(page) || !PageHead(page));
  +VM_BUG_ON(!PageCompound(page));
  +VM_BUG_ON(!PageHead(page));

weird... but anyway after this patch code disappears completely.

  add/remove: 0/0 grow/shrink: 7/97 up/down: 135/-1784 (-1649)

Signed-off-by: Konstantin Khlebnikov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: Cong Wang <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>