linux-kernel - [PATCH AUTOSEL 4.14 15/45] xtensa: SMP: limit number of possible CPUs by NR

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Message-Id: <20190223210835.201708-15-sashal@kernel.org>
Date:   Sat, 23 Feb 2019 16:08:05 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Max Filippov <jcmvbkbc@...il.com>, Sasha Levin <sashal@...nel.org>,
        linux-xtensa@...ux-xtensa.org
Subject: [PATCH AUTOSEL 4.14 15/45] xtensa: SMP: limit number of possible CPUs by NR_CPUS

From: Max Filippov <jcmvbkbc@...il.com>

[ Upstream commit 25384ce5f9530def39421597b1457d9462df6455 ]

This fixes the following warning at boot when the kernel is booted on a
board with more CPU cores than was configured in NR_CPUS:

  smp_init_cpus: Core Count = 8
  smp_init_cpus: Core Id = 0
  ------------[ cut here ]------------
  WARNING: CPU: 0 PID: 0 at include/linux/cpumask.h:121 smp_init_cpus+0x54/0x74
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Not tainted 5.0.0-rc3-00015-g1459333f88a0 #124
  Call Trace:
    __warn$part$3+0x6a/0x7c
    warn_slowpath_null+0x35/0x3c
    smp_init_cpus+0x54/0x74
    setup_arch+0x1c0/0x1d0
    start_kernel+0x44/0x310
    _startup+0x107/0x107

Signed-off-by: Max Filippov <jcmvbkbc@...il.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/xtensa/kernel/smp.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/xtensa/kernel/smp.c b/arch/xtensa/kernel/smp.c
index 80be6449c497e..be1f280c322cd 100644
--- a/arch/xtensa/kernel/smp.c
+++ b/arch/xtensa/kernel/smp.c
@@ -96,6 +96,11 @@ void __init smp_init_cpus(void)
 	pr_info("%s: Core Count = %d\n", __func__, ncpus);
 	pr_info("%s: Core Id = %d\n", __func__, core_id);
 
+	if (ncpus > NR_CPUS) {
+		ncpus = NR_CPUS;
+		pr_info("%s: limiting core count by %d\n", __func__, ncpus);
+	}
+
 	for (i = 0; i < ncpus; ++i)
 		set_cpu_possible(i, true);
 }
-- 
2.19.1