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authorTim Chen <tim.c.chen@linux.intel.com>2016-10-07 17:00:02 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-10-07 18:46:28 -0700
commit03e86dba5b628a13a58adae62e5b918b969ae93e (patch)
treea35beb97eff3c45cb1bb83eeb9570d9bf58b30e4 /mm
parentdbe6ec815641aa22b50775aaeb47fa3a8d04ccf1 (diff)
cpu: fix node state for whether it contains CPU
In current kernel code, we only call node_set_state(cpu_to_node(cpu), N_CPU) when a cpu is hot plugged. But we do not set the node state for N_CPU when the cpus are brought online during boot. So this could lead to failure when we check to see if a node contains cpu with node_state(node_id, N_CPU). One use case is in the node_reclaime function: /* * Only run node reclaim on the local node or on nodes that do * not * have associated processors. This will favor the local * processor * over remote processors and spread off node memory allocations * as wide as possible. */ if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id()) return NODE_RECLAIM_NOSCAN; I instrumented the kernel to call this function after boot and it always returns 0 on a x86 desktop machine until I apply the attached patch. int num_cpu_node(void) { int i, nr_cpu_nodes = 0; for_each_node(i) { if (node_state(i, N_CPU)) ++ nr_cpu_nodes; } return nr_cpu_nodes; } Fix this by checking each node for online CPU when we initialize vmstat that's responsible for maintaining node state. Link: http://lkml.kernel.org/r/20160829175922.GA21775@linux.intel.com Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: <Huang@linux.intel.com> Cc: Ying <ying.huang@intel.com> Cc: Andi Kleen <andi@firstfloor.org> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/vmstat.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/mm/vmstat.c b/mm/vmstat.c
index dc04e76c7950..73aab319969d 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1715,6 +1715,16 @@ static void __init start_shepherd_timer(void)
round_jiffies_relative(sysctl_stat_interval));
}
+static void __init init_cpu_node_state(void)
+{
+ int cpu;
+
+ get_online_cpus();
+ for_each_online_cpu(cpu)
+ node_set_state(cpu_to_node(cpu), N_CPU);
+ put_online_cpus();
+}
+
static void vmstat_cpu_dead(int node)
{
int cpu;
@@ -1772,6 +1782,7 @@ static int __init setup_vmstat(void)
#ifdef CONFIG_SMP
cpu_notifier_register_begin();
__register_cpu_notifier(&vmstat_notifier);
+ init_cpu_node_state();
start_shepherd_timer();
cpu_notifier_register_done();