From: Dave Hansen <dave.hansen@linux.intel.com>
Date: Tue, 30 Sep 2014 21:45:46 +0000 (-0700)
Subject: sched/x86: Fix up typo in topology detection
X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=728e5653e6fdb2a0892e94a600aef8c9a036c7eb;p=deliverable%2Flinux.git

sched/x86: Fix up typo in topology detection

Commit:

  cebf15eb09a2 ("x86, sched: Add new topology for multi-NUMA-node CPUs")

some code to try to detect the situation where we have a NUMA node
inside of the "DIE" sched domain.

It detected this by looking for cpus which match_die() but do not match
NUMA nodes via topology_same_node().

I wrote it up as:

	if (match_die(c, o) == !topology_same_node(c, o))

which actually seemed to work some of the time, albiet
accidentally.

It should have been doing an &&, not an ==.

This code essentially chopped off the "DIE" domain on one of
Andrew Morton's systems.  He reported that this patch fixed his
issue.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Dave Hansen <dave@sr71.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Lan Tianyu <tianyu.lan@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Link: http://lkml.kernel.org/r/20140930214546.FD481CFF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 8de8eb756d1f..bae9e09291ec 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -445,7 +445,7 @@ void set_cpu_sibling_map(int cpu)
 			} else if (i != cpu && !c->booted_cores)
 				c->booted_cores = cpu_data(i).booted_cores;
 		}
-		if (match_die(c, o) == !topology_same_node(c, o))
+		if (match_die(c, o) && !topology_same_node(c, o))
 			primarily_use_numa_for_topology();
 	}
 }