From: tip-bot for Samuel Neves <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: douly.fnst@cn.fujitsu.com, sneves@dei.uc.pt,
peterz@infradead.org, mingo@kernel.org, hpa@zytor.com,
torvalds@linux-foundation.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de
Subject: [tip:x86/urgent] x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU hotplug operations
Date: Fri, 23 Feb 2018 00:29:17 -0800 [thread overview]
Message-ID: <tip-4596749339e06dc7a424fc08a15eded850ed78b7@git.kernel.org> (raw)
In-Reply-To: <20180221205036.5244-1-sneves@dei.uc.pt>
Commit-ID: 4596749339e06dc7a424fc08a15eded850ed78b7
Gitweb: https://git.kernel.org/tip/4596749339e06dc7a424fc08a15eded850ed78b7
Author: Samuel Neves <sneves@dei.uc.pt>
AuthorDate: Wed, 21 Feb 2018 20:50:36 +0000
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 23 Feb 2018 08:47:47 +0100
x86/topology: Update the 'cpu cores' field in /proc/cpuinfo correctly across CPU hotplug operations
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.
Tested-by: Dou Liyang <douly.fnst@cn.fujitsu.com>
Signed-off-by: Samuel Neves <sneves@dei.uc.pt>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: jgross@suse.com
Cc: luto@kernel.org
Cc: prarit@redhat.com
Cc: vkuznets@redhat.com
Link: http://lkml.kernel.org/r/20180221205036.5244-1-sneves@dei.uc.pt
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
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();
}
prev parent reply other threads:[~2018-02-23 8:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-21 20:50 [PATCH] smpboot: correctly update number of booted cores Samuel Neves
2018-02-22 8:07 ` Dou Liyang
2018-02-23 8:29 ` tip-bot for Samuel Neves [this message]
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