Messages in this thread | | | Date | Mon, 28 Nov 2011 10:17:03 +0100 | From | Johannes Weiner <> | Subject | Re: [patch 4/8] mm: memcg: lookup_page_cgroup (almost) never returns NULL |
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On Mon, Nov 28, 2011 at 12:33:31PM +0530, Balbir Singh wrote: > On Wed, Nov 23, 2011 at 9:12 PM, Johannes Weiner <hannes@cmpxchg.org> wrote: > > From: Johannes Weiner <jweiner@redhat.com> > > > > Pages have their corresponding page_cgroup descriptors set up before > > they are used in userspace, and thus managed by a memory cgroup. > > > > The only time where lookup_page_cgroup() can return NULL is in the > > page sanity checking code that executes while feeding pages into the > > page allocator for the first time. > > > > This is a legacy check from the days when we allocated PC during fault > time on demand. It might make sense to assert on !pc in DEBUG_VM mode > at some point in the future
I don't think a BUG_ON bears more information than a null-pointer dereference.
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