On Tue, May 12, 2026 at 5:18 PM Albert Esteve aesteve@redhat.com wrote:
On embedded platforms a central process often allocates dma-buf memory on behalf of client applications. Without a way to attribute the charge to the requesting client's cgroup, the cost lands on the allocator, making per-cgroup memory limits ineffective for the actual consumers.
Add charge_pid_fd to struct dma_heap_allocation_data. When set to a valid pidfd, DMA_HEAP_IOCTL_ALLOC resolves the target task's memcg and charges the buffer there via mem_cgroup_charge_dmabuf() inside dma_heap_buffer_alloc(). Without charge_pid_fd, and with the mem_accounting module parameter enabled, the buffer is charged to the allocator's own cgroup.
Additionally, commit 3c227be90659 ("dma-buf: system_heap: account for system heap allocation in memcg") adds __GFP_ACCOUNT to system-heap page allocations. Keeping __GFP_ACCOUNT would charge the same pages twice (once to kmem, once to MEMCG_DMABUF), thus remove it and route all accounting through a single MEMCG_DMABUF path.
[...]
if (mem_accounting)flags |= __GFP_ACCOUNT;
Hi Albert,
would it be better to move this and its description to patch 1? It looks like patch 1 already introduces the double accounting changes, and patch 2 is mainly just supporting remote charging.
Also, mem_accounting is only used by system_heap.c; has this patchset also eliminated its need?
Thanks Barry