[tip:perf/urgent] perf bench numa: Fix assertion for nodes bitfield

From: tip-bot for Jakub Jelen
Date: Thu Mar 24 2016 - 03:38:45 EST

Commit-ID: 3c52b658b8e4fbbf7975932bbdc4798421dbcb15
Gitweb: http://git.kernel.org/tip/3c52b658b8e4fbbf7975932bbdc4798421dbcb15
Author: Jakub Jelen <jakuje@xxxxxxxxx>
AuthorDate: Sat, 19 Mar 2016 12:58:07 +0100
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 21 Mar 2016 17:46:57 -0300

perf bench numa: Fix assertion for nodes bitfield

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>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jakub Jelen <jjelen@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: trivial@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1458388687-24421-1-git-send-email-jakuje@xxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
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 5049d63..7500d95 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);