On Thu 15-08-19 22:16:43, Daniel Vetter wrote: > On Thu, Aug 15, 2019 at 9:35 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote: [...] > > > The last detail is I'm still unclear what a GFP flags a blockable > > > invalidate_range_start() should use. Is GFP_KERNEL OK? > > > > I hope I will not make this muddy again ;) > > invalidate_range_start in the blockable mode can use/depend on any sleepable > > allocation allowed in the context it is called from. So in other words > > it is no different from any other function in the kernel that calls into > > allocator. As the API is missing gfp context then I hope it is not > > called from any restricted contexts (except from the oom which we have > > !blockable for). > > Hm, that's new to me. I thought mmu notifiers very much can be called > from direct reclaim paths, so you have to be extremely careful with > getting back into that one. Correct, I should have added that notifier callbacks ideally do not allocate any memory. They can block and even that is quite a pain to be honest. -- Michal Hocko SUSE Labs
