linux-kernel - [PATCH] clear_tasks_mm_cpumask(cpu) is added to arch_cpuhp_cleanup_dead

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Message-ID: <20250916165658.19052-1-danil.skrebenkov@cloudbear.ru>
Date: Tue, 16 Sep 2025 19:56:54 +0300
From: Danil Skrebenkov <danil.skrebenkov@...udbear.ru>
To: 
Cc: Danil Skrebenkov <danil.skrebenkov@...udbear.ru>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>,
	Alexandre Ghiti <alex@...ti.fr>,
	Charlie Jenkins <charlie@...osinc.com>,
	WangYuli <wangyuli@...ontech.com>,
	linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] clear_tasks_mm_cpumask(cpu) is added to arch_cpuhp_cleanup_dead_cpu

openSBI v1.7 adds harts checks for ipi operations. Especially it
adds comparison between hmask passed as an argument from linux
and mask of online harts (from openSBI side). If they don't
fit each other the error occurs.

When cpu is offline, cpu_online_mask is explicitly cleared in
__cpu_disable. However, there is no explicit clearing of
mm_cpumask. mm_cpumask is used for rfence operations that
call openSBI RFENCE extension which uses ipi to remote harts.
If hart is offline there may be error if mask of linux is not
as mask of online harts in openSBI.

this patch adds explicit clearing of mm_cpumask for offline hart.

Signed-off-by: Danil Skrebenkov <danil.skrebenkov@...udbear.ru>
---
 arch/riscv/kernel/cpu-hotplug.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/kernel/cpu-hotplug.c b/arch/riscv/kernel/cpu-hotplug.c
index a1e38ecfc8be..3f50d3dd76c6 100644
--- a/arch/riscv/kernel/cpu-hotplug.c
+++ b/arch/riscv/kernel/cpu-hotplug.c
@@ -54,6 +54,7 @@ void arch_cpuhp_cleanup_dead_cpu(unsigned int cpu)

 	pr_notice("CPU%u: off\n", cpu);

+	clear_tasks_mm_cpumask(cpu);
 	/* Verify from the firmware if the cpu is really stopped*/
 	if (cpu_ops->cpu_is_stopped)
 		ret = cpu_ops->cpu_is_stopped(cpu);
-- 
2.43.0