mm: page_cgroup: check page_cgroup arrays in lookup_page_cgroup() only when necessary

lookup_page_cgroup() is usually used only against pages that are used in
userspace.

The exception is the CONFIG_DEBUG_VM-only memcg check from the page
allocator: it can run on pages without page_cgroup descriptors allocated
when the pages are fed into the page allocator for the first time during
boot or memory hotplug.

Include the array check only when CONFIG_DEBUG_VM is set and save the
unnecessary check in production kernels.

Signed-off-by: Johannes Weiner <[email protected]>
Acked-by: KAMEZAWA Hiroyuki <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Balbir Singh <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hugh Dickins <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions