mm, rmap: handle anon_vma_prepare() common case inline

anon_vma_prepare() is mostly a large "if (unlikely(...))" block, as the
expected common case is that an anon_vma already exists.  We could turn
the condition around and return 0, but it also makes sense to do it
inline and avoid a call for the common case.

Bloat-o-meter naturally shows that inlining the check has some code size
costs:

add/remove: 1/1 grow/shrink: 4/0 up/down: 475/-373 (102)
function                                     old     new   delta
__anon_vma_prepare                             -     359    +359
handle_mm_fault                             2744    2796     +52
hugetlb_cow                                 1146    1170     +24
hugetlb_fault                               2123    2145     +22
wp_page_copy                                1469    1487     +18
anon_vma_prepare                             373       -    -373

Checking the asm however confirms that the hot paths now avoid a call,
which is moved away.

[[email protected]: coding-style fixes]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Vlastimil Babka <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions