Re: [PATCH] slub: Don't throw away partial remote slabs if there is no local memory

Wanpeng Li
2014-01-24T03:09:18Z

Hi Christoph,
On Mon, Jan 20, 2014 at 04:13:30PM -0600, Christoph Lameter wrote:
>On Mon, 20 Jan 2014, Wanpeng Li wrote:
>
>> >+ enum zone_type high_zoneidx = gfp_zone(flags);
>> >
>> >+ if (!node_present_pages(searchnode)) {
>> >+ zonelist = node_zonelist(searchnode, flags);
>> >+ for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
>> >+ searchnode = zone_to_nid(zone);
>> >+ if (node_present_pages(searchnode))
>> >+ break;
>> >+ }
>> >+ }
>> > object = get_partial_node(s, get_node(s, searchnode), c, flags);
>> > if (object || node != NUMA_NO_NODE)
>> > return object;
>> >
>>
>> The patch fix the bug. However, the kernel crashed very quickly after running
>> stress tests for a short while:
>
>This is not a good way of fixing it. How about not asking for memory from
>nodes that are memoryless? Use numa_mem_id() which gives you the next node
>that has memory instead of numa_node_id() (gives you the current node
>regardless if it has memory or not).

diff --git a/mm/slub.c b/mm/slub.c
index 545a170..a1c6040 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1700,6 +1700,9 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
void *object;
int searchnode = (node == NUMA_NO_NODE) ? numa_node_id() : node;

+ if (!node_present_pages(searchnode))
+ searchnode = numa_mem_id();
+
object = get_partial_node(s, get_node(s, searchnode), c, flags);
if (object || node != NUMA_NO_NODE)
return object;