(Cc Vlastimil)
On Sat, 25 May 2019 15:07:23 +0800 zhong jiang <zhongjiang@xxxxxxxxxx> wrote:
> We bind an different node to different vma, Unluckily,
> it will bind different vma to same node by checking the /proc/pid/numa_maps.
> Commit 213980c0f23b ("mm, mempolicy: simplify rebinding mempolicies when updating cpusets")
> has introduced the issue. when we change memory policy by seting cpuset.mems,
> A process will rebind the specified policy more than one times.
> if the cpuset_mems_allowed is not equal to user specified nodes. hence the issue will trigger.
> Maybe result in the out of memory which allocating memory from same node.
>
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -345,7 +345,7 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes)
> else {
> nodes_remap(tmp, pol->v.nodes,pol->w.cpuset_mems_allowed,
> *nodes);
> - pol->w.cpuset_mems_allowed = tmp;
> + pol->w.cpuset_mems_allowed = *nodes;
> }
>
> if (nodes_empty(tmp))
hm, I'm not surprised the code broke. What the heck is going on in
there? It used to have a perfunctory comment, but Vlastimil deleted
it.
Could someone please propose a comment for the above code block
explaining why we're doing what we do?
