Re: [PATCH] mm, page_alloc: actually ignore mempolicies for high priority allocations

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

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() ?