oom: suppress nodes that are not allowed from meminfo on oom kill

The oom killer is extremely verbose for machines with a large number of
cpus and/or nodes.  This verbosity can often be harmful if it causes other
important messages to be scrolled from the kernel log and incurs a
signicant time delay, specifically for kernels with CONFIG_NODES_SHIFT >
8.

This patch causes only memory information to be displayed for nodes that
are allowed by current's cpuset when dumping the VM state.  Information
for all other nodes is irrelevant to the oom condition; we don't care if
there's an abundance of memory elsewhere if we can't access it.

This only affects the behavior of dumping memory information when an oom
is triggered.  Other dumps, such as for sysrq+m, still display the
unfiltered form when using the existing show_mem() interface.

Additionally, the per-cpu pageset statistics are extremely verbose in oom
killer output, so it is now suppressed.  This removes

	nodes_weight(current->mems_allowed) * (1 + nr_cpus)

lines from the oom killer output.

Callers may use __show_mem(SHOW_MEM_FILTER_NODES) to filter disallowed
nodes.

Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 2 deletions

diff --git a/lib/show_mem.c b/lib/show_mem.c
index fdc77c8..d8d602b 100644
--- a/lib/show_mem.c
+++ b/lib/show_mem.c
@@ -9,14 +9,14 @@
 #include <linux/nmi.h>
 #include <linux/quicklist.h>
 
-void show_mem(void)
+void __show_mem(unsigned int filter)
 {
 	pg_data_t *pgdat;
 	unsigned long total = 0, reserved = 0, shared = 0,
 		nonshared = 0, highmem = 0;
 
 	printk("Mem-Info:\n");
-	show_free_areas();
+	__show_free_areas(filter);
 
 	for_each_online_pgdat(pgdat) {
 		unsigned long i, flags;
@@ -61,3 +61,8 @@ void show_mem(void)
 		quicklist_total_size());
 #endif
 }
+
+void show_mem(void)
+{
+	__show_mem(0);
+}