mirror of https://gitee.com/openkylin/linux.git
3af229f207
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> |
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