Hello, Tang. On Sat, Sep 26, 2015 at 05:31:07PM +0800, Tang Chen wrote: > >>@@ -307,13 +307,19 @@ static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask, > >> if (nid < 0) > >> nid = numa_node_id(); > >>+ if (!node_online(nid)) > >>+ nid = get_near_online_node(nid); > >>+ > >> return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask)); > >> } > >Why not just update node_data[]->node_zonelist in the first place? > > zonelist will be rebuilt in __offline_pages() when the zone is not populated > any more. > > Here, getting the best near online node is for those cpus on memory-less > nodes. > > In the original code, if nid is NUMA_NO_NODE, the node the current cpu > resides in > will be chosen. And if the node is memory-less node, the cpu will be mapped > to its > best near online node. > > But this patch-set will map the cpu to its original node, so numa_node_id() > may return > a memory-less node to allocator. And then memory allocation may fail. Correct me if I'm wrong but the zonelist dictates which memory areas the page allocator is gonna try to from, right? What I'm wondering is why we aren't handling memory-less nodes by simply updating their zonelists. I mean, if, say, node 2 is memory-less, its zonelist can simply point to zones from other nodes, right? What am I missing here? Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>