linux-kernel - [tip:sched/core] sched/x86: Fix up typo in topology detection

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Date:	Thu, 2 Oct 2014 22:27:26 -0700
From:	tip-bot for Dave Hansen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	imammedo@...hat.com, torvalds@...ux-foundation.org,
	peterz@...radead.org, jan.kiszka@...mens.com, toshi.kani@...com,
	tianyu.lan@...el.com, dave@...1.net, akpm@...ux-foundation.org,
	tglx@...utronix.de, dave.hansen@...ux.intel.com, prarit@...hat.com,
	rientjes@...gle.com
Subject: [tip:sched/core] sched/x86: Fix up typo in topology detection

Commit-ID:  728e5653e6fdb2a0892e94a600aef8c9a036c7eb
Gitweb:     http://git.kernel.org/tip/728e5653e6fdb2a0892e94a600aef8c9a036c7eb
Author:     Dave Hansen <dave.hansen@...ux.intel.com>
AuthorDate: Tue, 30 Sep 2014 14:45:46 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 3 Oct 2014 05:46:52 +0200

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@...ux.intel.com>
Reported-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Dave Hansen <dave@...1.net>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: David Rientjes <rientjes@...gle.com>
Cc: Igor Mammedov <imammedo@...hat.com>
Cc: Jan Kiszka <jan.kiszka@...mens.com>
Cc: Lan Tianyu <tianyu.lan@...el.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Prarit Bhargava <prarit@...hat.com>
Cc: Toshi Kani <toshi.kani@...com>
Link: http://lkml.kernel.org/r/20140930214546.FD481CFF@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/kernel/smpboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 8de8eb7..bae9e09 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();
 	}
 }
--
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