On Mon, Oct 5, 2015 at 1:25 PM, Alexander Duyck <alexander.duyck@xxxxxxxxx> wrote: > On 10/05/2015 06:59 AM, Vlastimil Babka wrote: >> >> On 10/02/2015 12:18 PM, Konstantin Khlebnikov wrote: >>> >>> When openvswitch tries allocate memory from offline numa node 0: >>> stats = kmem_cache_alloc_node(flow_stats_cache, GFP_KERNEL | __GFP_ZERO, >>> 0) >>> It catches VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES || !node_online(nid)) >>> [ replaced with VM_WARN_ON(!node_online(nid)) recently ] in linux/gfp.h >>> This patch disables numa affinity in this case. >>> >>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> >> >> >> ... >> >>> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c >>> index f2ea83ba4763..c7f74aab34b9 100644 >>> --- a/net/openvswitch/flow_table.c >>> +++ b/net/openvswitch/flow_table.c >>> @@ -93,7 +93,8 @@ struct sw_flow *ovs_flow_alloc(void) >>> >>> /* Initialize the default stat node. */ >>> stats = kmem_cache_alloc_node(flow_stats_cache, >>> - GFP_KERNEL | __GFP_ZERO, 0); >>> + GFP_KERNEL | __GFP_ZERO, >>> + node_online(0) ? 0 : NUMA_NO_NODE); >> >> >> Stupid question: can node 0 become offline between this check, and the >> VM_WARN_ON? :) BTW what kind of system has node 0 offline? > > > Another question to ask would be is it possible for node 0 to be online, but > be a memoryless node? > > I would say you are better off just making this call kmem_cache_alloc. I > don't see anything that indicates the memory has to come from node 0, so > adding the extra overhead doesn't provide any value. I agree that this at least makes me wonder, though I actually have concerns in the opposite direction - I see assumptions about this being on node 0 in net/openvswitch/flow.c. Jarno, since you original wrote this code, can you take a look to see if everything still makes sense? -- 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>