[PATCH] fix BUG_ON(!PageSlab) from fallback_alloc

[PATCH] fix BUG_ON(!PageSlab) from fallback_alloc

pdflush hit the BUG_ON(!PageSlab(page)) in kmem_freepages called from
fallback_alloc: cache_grow already freed those pages when alloc_slabmgmt
failed.  But it wouldn't have freed them if __GFP_NO_GROW, so make sure
fallback_alloc doesn't waste its time on that case.

Signed-off-by: Hugh Dickins <[email protected]>
Acked-by: Christoph Lameter <[email protected]>
Acked-by: Pekka J Enberg <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>