[PATCH] perf bench numa: Fix assertion for nodes bitfield

From: Jakub Jelen
Date: Sat Mar 19 2016 - 07:59:05 EST

Comparing bits and bytes in numa benchmark assertion

I hit the issue on two socket Power8 machine presenting its numa nodes as
0,1,16,17 (according to numactl). Therefore I got error
(and hang of parent process):

perf: bench/numa.c:296: bind_to_memnode: Assertion `!(g->p.nr_nodes > (int)sizeof(nodemask))' failed.

This is obviously false positive. We can fit all the 18 nodes into
bitfield of 8 bytes (long on 64b architecture).

Signed-off-by: Jakub Jelen <jakuje@xxxxxxxxx>
Hello kernel list.
This is my first patch for kernel, so if I missed some of the guidelines,
please be patient :) I hope everything is explained in the commit message.


tools/perf/bench/numa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/bench/numa.c b/tools/perf/bench/numa.c
index 870b7e6..5276b24 100644
--- a/tools/perf/bench/numa.c
+++ b/tools/perf/bench/numa.c
@@ -293,7 +293,7 @@ static void bind_to_memnode(int node)
if (node == -1)

- BUG_ON(g->p.nr_nodes > (int)sizeof(nodemask));
+ BUG_ON(g->p.nr_nodes > (int)sizeof(nodemask)*8);
nodemask = 1L << node;

ret = set_mempolicy(MPOL_BIND, &nodemask, sizeof(nodemask)*8);