dma-buf: system_heap: account for system heap allocation in memcg

dma-buf: system_heap: account for system heap allocation in memcg

The system dma-buf heap lets userspace allocate buffers from the page
allocator. However, these allocations are not accounted for in memcg,
allowing processes to escape limits that may be configured.

Pass __GFP_ACCOUNT for system heap allocations, based on the
dma_heap.mem_accounting parameter, to use memcg and account for them.

Signed-off-by: Eric Chanudet <echanude@redhat.com>
Reviewed-by: T.J. Mercier <tjmercier@google.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Link: https://patch.msgid.link/20260116-dmabuf-heap-system-memcg-v3-2-ecc6b62cc446@redhat.com