Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-11 22:51:42 +00:00
Code Issues Packages Projects Releases Wiki Activity

powerpc/numa: Reset node_possible_map to only node_online_map

Browse Source 
Raghu noticed an issue with excessive memory allocation on power with a
simple cgroup test, specifically, in mem_cgroup_css_alloc ->
for_each_node -> alloc_mem_cgroup_per_zone_info(), which ends up blowing
up the kmalloc-2048 slab (to the order of 200MB for 400 cgroup
directories).

The underlying issue is that NODES_SHIFT on power is 8 (256 NUMA nodes
possible), which defines node_possible_map, which in turn defines the
value of nr_node_ids in setup_nr_node_ids and the iteration of
for_each_node.

In practice, we never see a system with 256 NUMA nodes, and in fact, we
do not support node hotplug on power in the first place, so the nodes
that are online when we come up are the nodes that will be present for
the lifetime of this kernel. So let's, at least, drop the NUMA possible
map down to the online map at runtime. This is similar to what x86 does
in its initialization routines.

mem_cgroup_css_alloc should also be fixed to only iterate over
memory-populated nodes and handle hotplug, but that is a separate
change.

Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
This commit is contained in:
Nishanth Aravamudan 2015-03-10 16:50:59 -07:00 committed by Michael Ellerman
parent 6eca8933d3
commit 3af229f207
1 changed files with 7 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
arch/powerpc/mm/numa.c
View File

@ -958,6 +958,13 @@ void __init initmem_init(void)
memblock_dump_all();
/*
* Reduce the possible NUMA nodes to the online NUMA nodes,
* since we do not support node hotplug. This ensures that we
* lower the maximum NUMA node ID to what is actually present.
*/
nodes_and(node_possible_map, node_possible_map, node_online_map);
for_each_online_node(nid) {
unsigned long start_pfn, end_pfn;