On Mon 27-11-17 12:21:21, Andi Kleen wrote: > On Mon, Nov 27, 2017 at 08:57:32PM +0100, Michal Hocko wrote: > > On Mon 27-11-17 19:32:18, Michal Hocko wrote: > > > On Mon 27-11-17 09:25:16, Andi Kleen wrote: > > [...] > > > > The reason the limit was there originally because it allows a DoS > > > > attack against the kernel by filling all unswappable memory up with > > > > VMAs. > > > > > > We can reduce the effect by accounting vmas to memory cgroups. > > > > As it turned out we already do. > > vm_area_cachep = KMEM_CACHE(vm_area_struct, SLAB_PANIC|SLAB_ACCOUNT); > > That only helps if you have memory cgroups enabled. It would be a regression > to break the accounting on all the systems that don't.
I agree. And I didn't say we should remove the existing limit. I am just saying that we can reduce existing problems by increasing the limit and relying on memcg accounting where possible. -- Michal Hocko SUSE Labs
