linux-kernel - [PATCH] x86/apic: Do not use smp_processor

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Message-Id: <20170926170845.13955-1-bp@alien8.de>
Date:   Tue, 26 Sep 2017 19:08:45 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     X86 ML <x86@...nel.org>
Cc:     LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] x86/apic: Do not use smp_processor_id() in preemptible code

From: Borislav Petkov <bp@...e.de>

Call stack is:

  check_preemption_disabled
  ? x2apic_prepare_cpu
  x2apic_dead_cpu
  cpuhp_invoke_callback
  ? cpuhp_kick_ap_work
  ? cpumask_next
  _cpu_down
  freeze_secondary_cpus
  hibernation_snapshot
  ...

i.e., box is doing suspend-to-disk.

Signed-off-by: Borislav Petkov <bp@...e.de>
---
 arch/x86/kernel/apic/x2apic_cluster.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/x2apic_cluster.c b/arch/x86/kernel/apic/x2apic_cluster.c
index 3da94277140f..6050c5364bdc 100644
--- a/arch/x86/kernel/apic/x2apic_cluster.c
+++ b/arch/x86/kernel/apic/x2apic_cluster.c
@@ -156,7 +156,7 @@ static int x2apic_dead_cpu(unsigned int dead_cpu)
 {
 	struct cluster_mask *cmsk = per_cpu(cluster_masks, dead_cpu);
 
-	cpumask_clear_cpu(smp_processor_id(), &cmsk->mask);
+	cpumask_clear_cpu(dead_cpu, &cmsk->mask);
 	free_cpumask_var(per_cpu(ipi_mask, dead_cpu));
 	return 0;
 }
-- 
2.13.0