On Wed 15-12-21 11:05:12, Michal Hocko wrote: > On Tue 14-12-21 12:57:48, Andrew Morton wrote: > > On Tue, 14 Dec 2021 11:11:54 +0100 Michal Hocko <mhocko@xxxxxxxx> wrote: > > > > > > I need some clarification here. It sounds like memoryless nodes work on > > > > x86, but hotplug + memoryless nodes isn't a supported use case or you're > > > > introducing it as a new use case? > > > > > > > > If this is a new use case, then I'm inclined to say this patch should > > > > NOT go in and a proper fix should be implemented on hotplug's side. I > > > > don't want to be in the business of having/seeing this conversation > > > > reoccur because we just papered over this issue in percpu. > > > > > > The patch still seems to be in the mmotm tree. I have sent a different > > > fix candidate [1] which should be more robust and cover also other potential > > > places. > > > > > > [1] http://lkml.kernel.org/r/20211214100732.26335-1-mhocko@xxxxxxxxxx > > > > Is cool, I'm paying attention. > > > > We do want something short and simple for backporting to -stable (like > > Alexey's patch) so please bear that in mind while preparing an > > alternative. > > I think we want something that fixes the underlying problem. Please keep > in mind that the pcp allocation is not the only place to hit the issue. > We have more. I do not want we want to handle each and every one > separately. > > I am definitly not going to push for my solution but if there is a > consensus this is the right approach then I do not think we really want > to implement these partial workarounds. Btw. I forgot to add that if we do not agree on the preallocation approach then the approach should be something like http://lkml.kernel.org/r/51c65635-1dae-6ba4-daf9-db9df0ec35d8@xxxxxxxxxx proposed by David. -- Michal Hocko SUSE Labs
