From 33fce0113da2f8a5c1bbce0c46a8b131500f1677 Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Mon, 23 Sep 2019 15:35:52 -0700 Subject: [PATCH] mm/memory_hotplug.c: prevent memory leak when reusing pgdat When offlining a node in try_offline_node(), pgdat is not released. So that pgdat could be reused in hotadd_new_pgdat(). While we reallocate pgdat->per_cpu_nodestats if this pgdat is reused. This patch prevents the memory leak by just allocating per_cpu_nodestats when it is a new pgdat. Link: http://lkml.kernel.org/r/20190813020608.10194-1-richardw.yang@linux.intel.com Signed-off-by: Wei Yang Acked-by: Michal Hocko Cc: Oscar Salvador Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 3706a137d880..c28e5dd017ba 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -925,8 +925,11 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) if (!pgdat) return NULL; + pgdat->per_cpu_nodestats = + alloc_percpu(struct per_cpu_nodestat); arch_refresh_nodedata(nid, pgdat); } else { + int cpu; /* * Reset the nr_zones, order and classzone_idx before reuse. * Note that kswapd will init kswapd_classzone_idx properly @@ -935,6 +938,12 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) pgdat->nr_zones = 0; pgdat->kswapd_order = 0; pgdat->kswapd_classzone_idx = 0; + for_each_online_cpu(cpu) { + struct per_cpu_nodestat *p; + + p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu); + memset(p, 0, sizeof(*p)); + } } /* we can use NODE_DATA(nid) from here */ @@ -944,7 +953,6 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start) /* init node's zones as empty zones, we don't have any present pages.*/ free_area_init_core_hotplug(nid); - pgdat->per_cpu_nodestats = alloc_percpu(struct per_cpu_nodestat); /* * The node we allocated has no zone fallback lists. For avoiding