On Wed, Feb 05, 2020 at 02:33:47PM -0800, Dan Schatzberg wrote: > This modifies the shmem and mm charge logic so that now if there is no > mm set (as in the case of tmpfs backed loop device), we charge the > current memcg, if set. > > Signed-off-by: Dan Schatzberg <dschatzberg@xxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> It's a dependency for 2/2, but it's also an overdue cleanup IMO: it's always been a bit weird that 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. Thanks Dan
