Re: [PATCH v7 2/2] mm/oom_kill: The OOM reaper traverses the VMA maple tree in reverse order

[Michal Hocko <mhocko@suse.com>]

On Thu 04-09-25 22:12:48, Liam R. Howlett wrote:
> * Michal Hocko <mhocko@suse.com> [250904 08:21]:
> > On Wed 03-09-25 15:02:34, Liam R. Howlett wrote:
> > > * Michal Hocko <mhocko@suse.com> [250903 08:58]:
> > > > On Wed 03-09-25 17:27:29, zhongjinji wrote:
> > [...]
> > > mmu_notifier_release(mm) is called early in the exit_mmap() path should
> > > cause the mmu notifiers to be non-blocking (according to the comment in
> > > v6.0 source of exit_mmap [1].
> > 
> > I am not sure I follow you here. How does this relate to the actual
> > direction of the address space freeing?
> 
> It doesn't relate to the direction of the address freeing, I think it
> explains the perf data a bit.
> 
> The exit_mmap() would have a decrease in mmu related work while this
> thread will have an increase, I think.
> 
> If they race, this thread gets virtually nothing while exit does all of
> the work.  If they don't race then the work is split.
> 
> Does that make sense?

OK, I can see what you mean now. Thanks! I believe we need more data to
understand what is actually going on here. Having the overall duration
should help to get that.

-- 
Michal Hocko
SUSE Labs