From: Samuel Neves <sneves@dei.uc.pt>
To: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com,
x86@kernel.org, jgross@suse.com, douly.fnst@cn.fujitsu.com,
luto@kernel.org, prarit@redhat.com, ak@linux.intel.com,
vkuznets@redhat.com, linux-kernel@vger.kernel.org
Cc: Samuel Neves <sneves@dei.uc.pt>
Subject: [PATCH] smpboot: correctly update number of booted cores
Date: Wed, 21 Feb 2018 20:50:36 +0000
Message-ID: <20180221205036.5244-1-sneves@dei.uc.pt> (raw)
Without this fix, /proc/cpuinfo will display an incorrect amount
of CPU cores, after bringing them offline and online again, as
exemplified below:
$ cat /proc/cpuinfo | grep cores
cpu cores : 4
cpu cores : 8
cpu cores : 8
cpu cores : 20
cpu cores : 4
cpu cores : 3
cpu cores : 2
cpu cores : 2
This patch fixes this by always zeroing the booted_cores variable
upon turning off a logical CPU.
Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
---
arch/x86/kernel/smpboot.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9eee25d07586..ff99e2b6fc54 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1437,6 +1437,7 @@ static void remove_siblinginfo(int cpu)
cpumask_clear(topology_sibling_cpumask(cpu));
cpumask_clear(topology_core_cpumask(cpu));
c->cpu_core_id = 0;
+ c->booted_cores = 0;
cpumask_clear_cpu(cpu, cpu_sibling_setup_mask);
recompute_smt_state();
}
--
2.14.3
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Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-21 20:50 Samuel Neves [this message]
2018-02-22 8:07 ` Dou Liyang
2018-02-23 8:29 ` [tip:x86/urgent] x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU hotplug operations tip-bot for Samuel Neves
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