On Sat 18-08-18 22:02:14, Tetsuo Handa wrote:
> On 2018/08/16 19:03, Michal Hocko wrote:
> > The code is quite subtle and we have a bad history of copying stuff
> > without rethinking whether the code still is needed. Which is sad and a
> > clear sign that the code is too complex. I cannot say this change
> > doesn't have any subtle side effects but it makes the intention clear at
> > least so I _think_ it is good to go. If we find some unintended side
> > effects we should simply rethink the whole reset zonelist thing.
>
> Does this change affect
>
> /*
> * This is not a __GFP_THISNODE allocation, so a truncated nodemask in
> * the page allocator means a mempolicy is in effect. Cpuset policy
> * is enforced in get_page_from_freelist().
> */
> if (oc->nodemask &&
> !nodes_subset(node_states[N_MEMORY], *oc->nodemask)) {
> oc->totalpages = total_swap_pages;
> for_each_node_mask(nid, *oc->nodemask)
> oc->totalpages += node_spanned_pages(nid);
> return CONSTRAINT_MEMORY_POLICY;
> }
>
> in constrained_alloc() called from
>
> /*
> * Check if there were limitations on the allocation (only relevant for
> * NUMA and memcg) that may require different handling.
> */
> constraint = constrained_alloc(oc);
> if (constraint != CONSTRAINT_MEMORY_POLICY)
> oc->nodemask = NULL;
>
> in out_of_memory() ?
No practical difference AFAICS. We are losing the nodemask for oom
victims but their mere existance should make oom decisions void
and so the constrain shouldn't really matter.
--
Michal Hocko
SUSE Labs
