On Fri, May 15, 2020 at 11:09 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > On Fri, May 15, 2020 at 10:49:22AM -0700, Shakeel Butt wrote: > > On Fri, May 15, 2020 at 8:00 AM Roman Gushchin <guro@xxxxxx> wrote: > > > On Fri, May 15, 2020 at 06:44:44AM -0700, Shakeel Butt wrote: > > > > On Fri, May 15, 2020 at 6:24 AM Johannes Weiner <hannes@xxxxxxxxxxx> wrote: > > > > > You're right. It should only bypass the page_counter, but still set > > > > > page->mem_cgroup = root_mem_cgroup, just like user pages. > > > > > > What about kernel threads? We consider them belonging to the root memory > > > cgroup. Should their memory consumption being considered in root-level stats? > > > > > > I'm not sure we really want it, but I guess we need to document how > > > kernel threads are handled. > > > > What will be the cons of updating root-level stats for kthreads? > > Should kernel threads be doing GFP_ACCOUNT allocations without > memalloc_use_memcg()? GFP_ACCOUNT implies that the memory consumption > can be significant and should be attributed to userspace activity. > > If the kernel thread has no userspace entity to blame, it seems to > imply the same thing as a !GFP_ACCOUNT allocation: shared public > infrastructure, not interesting to account to any specific cgroup. > > I'm not sure if we have such allocations right now. But IMO we should > not account anything from kthreads, or interrupts for that matter, > /unless/ there is a specific active_memcg that was set by the kthread > or the interrupt. I totally agree with you but I think your response is about memory charging in IRQ/kthread context, a topic of a parallel patch from Zefan Li at [1]. Here we are discussing stats update for kthreads e.g. should we update root memcg's MEMCG_KERNEL_STACK_KB stat when we allocate stack for kernel threads? [1] http://lkml.kernel.org/r/3a721f62-5a66-8bc5-247b-5c8b7c51c555@xxxxxxxxxx
