Dan Schatzberg writes:
memalloc_use_memcg() worked for kernel allocations but was silently ignored for user pages. This patch establishes a precedence order for who gets charged: 1. If there is a memcg associated with the page already, that memcg is charged. This happens during swapin. 2. If an explicit mm is passed, mm->memcg is charged. This happens during page faults, which can be triggered in remote VMs (eg gup). 3. Otherwise consult the current process context. If it has configured a current->active_memcg, use that. Otherwise, current->mm->memcg. Previously, if a NULL mm was passed to mem_cgroup_try_charge (case 3) it would always charge the root cgroup. Now it looks up the current active_memcg first (falling back to charging the root cgroup if not set). Signed-off-by: Dan Schatzberg <schatzberg.dan@xxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Acked-by: Chris Down <chris@xxxxxxxxxxxxxx> Thanks! The clarification the v2 thread for this made things clear to me.
