Re: [patch 5/7] mm: page_cgroup: check page_cgroup arrays inlookup_page_cgroup() only when necessary

[KAMEZAWA Hiroyuki]

On Tue, 29 Nov 2011 11:52:03 +0100
Johannes Weiner <hannes@xxxxxxxxxxx> wrote:

> 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 <hannes@xxxxxxxxxxx>

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>


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