Commit 33fce011 authored by Wei Yang's avatar Wei Yang Committed by Linus Torvalds
Browse files

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: default avatarWei Yang <richardw.yang@linux.intel.com>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent b6c88d3b

mm/memory_hotplug.c

+9 −1
Original line number Diff line number Diff line
@@ -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