Hi, On 08/02/2018 04:15 AM, Michal Hocko wrote:
On Wed 01-08-18 15:04:17, Jeremy Linton wrote: [...]@@ -2519,6 +2519,8 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, if (unlikely(!node_match(page, searchnode))) { stat(s, ALLOC_NODE_MISMATCH); deactivate_slab(s, page, c->freelist, c); + if (!node_online(searchnode)) + node = NUMA_NO_NODE; goto new_slab;This is inherently racy. Numa node can get offline at any point after you check it here. Making it race free would involve some sort of locking and I am not really convinced this is a good idea.
I spent some time looking/thinking about this, and i'm pretty sure its not creating any new problems. But OTOH, I think the node_online() check is probably a bit misleading as what we really want to assure is that node<MAX_NUMNODES and that there is going to be a valid entry in NODE_DATA() so we don't deference null.
} } -- 2.14.3
