mm, slab: suppress out of memory warning unless debug is enabled

mm, slab: suppress out of memory warning unless debug is enabled

When the slab or slub allocators cannot allocate additional slab pages,
they emit diagnostic information to the kernel log such as current number
of slabs, number of objects, active objects, etc.  This is always coupled
with a page allocation failure warning since it is controlled by
!__GFP_NOWARN.

Suppress this out of memory warning if the allocator is configured without
debug supported.  The page allocation failure warning will indicate it is
a failed slab allocation, the order, and the gfp mask, so this is only
useful to diagnose allocator issues.

Since CONFIG_SLUB_DEBUG is already enabled by default for the slub
allocator, there is no functional change with this patch.  If debug is
disabled, however, the warnings are now suppressed.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>