mm: memcg/percpu: account percpu memory to memory cgroups

Percpu memory is becoming more and more widely used by various subsystems,
and the total amount of memory controlled by the percpu allocator can make
a good part of the total memory.

As an example, bpf maps can consume a lot of percpu memory, and they are
created by a user.  Also, some cgroup internals (e.g.  memory controller
statistics) can be quite large.  On a machine with many CPUs and big
number of cgroups they can consume hundreds of megabytes.

So the lack of memcg accounting is creating a breach in the memory
isolation.  Similar to the slab memory, percpu memory should be accounted
by default.

To implement the perpcu accounting it's possible to take the slab memory
accounting as a model to follow.  Let's introduce two types of percpu
chunks: root and memcg.  What makes memcg chunks different is an
additional space allocated to store memcg membership information.  If
__GFP_ACCOUNT is passed on allocation, a memcg chunk should be be used.
If it's possible to charge the corresponding size to the target memory
cgroup, allocation is performed, and the memcg ownership data is recorded.
System-wide allocations are performed using root chunks, so there is no
additional memory overhead.

To implement a fast reparenting of percpu memory on memcg removal, we
don't store mem_cgroup pointers directly: instead we use obj_cgroup API,
introduced for slab accounting.

[[email protected]: fix CONFIG_MEMCG_KMEM=n build errors and warning]
[[email protected]: move unreachable code, per Roman]
[[email protected]: mm/percpu: fix 'defined but not used' warning]
  Link: http://lkml.kernel.org/r/[email protected]

Signed-off-by: Roman Gushchin <[email protected]>
Signed-off-by: Bixuan Cui <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Acked-by: Dennis Zhou <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Tobin C. Harding <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: Bixuan Cui <[email protected]>
Cc: Michal Koutný <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions