From ff98a5f624d2910de050f1fc7f2a32769da86b51 Mon Sep 17 00:00:00 2001 From: Dietmar Eggemann Date: Fri, 29 Nov 2019 16:23:02 +0100 Subject: ARM: 8943/1: Fix topology setup in case of CPU hotplug for CONFIG_SCHED_MC Commit ca74b316df96 ("arm: Use common cpu_topology structure and functions.") changed cpu_coregroup_mask() from the ARM32 specific implementation in arch/arm/include/asm/topology.h to the one shared with ARM64 and RISCV in drivers/base/arch_topology.c. Currently on ARM32 (TC2 w/ CONFIG_SCHED_MC) the task scheduler setup code (w/ CONFIG_SCHED_DEBUG) shows this during CPU hotplug: ERROR: groups don't span domain->span It happens to CPUs of the cluster of the CPU which gets hot-plugged out on scheduler domain MC. Turns out that the shared cpu_coregroup_mask() requires that the hot-plugged CPU is removed from the core_sibling mask via remove_cpu_topology(). Otherwise the 'is core_sibling subset of cpumask_of_node()' doesn't work. In this case the task scheduler has to deal with cpumask_of_node instead of core_sibling which is wrong on scheduler domain MC. e.g. CPU3 hot-plugged out on TC2 [cluster0: 0,3-4 cluster1: 1-2]: cpu_coregroup_mask(): CPU3 cpumask_of_node=0-2,4 core_sibling=0,3-4 ^ should be: cpu_coregroup_mask(): CPU3 cpumask_of_node=0-2,4 core_sibling=0,4 Add remove_cpu_topology() to __cpu_disable() to remove the CPU from the topology masks in case of a CPU hotplug out operation. At the same time tweak store_cpu_topology() slightly so it will call update_siblings_masks() in case of CPU hotplug in operation via secondary_start_kernel()->smp_store_cpu_info(). This aligns the ARM32 implementation with the ARM64 one. Guarding remove_cpu_topology() with CONFIG_GENERIC_ARCH_TOPOLOGY is necessary since some Arm32 defconfigs (aspeed_g5_defconfig, milbeaut_m10v_defconfig, spear13xx_defconfig) specify an explicit # CONFIG_ARM_CPU_TOPOLOGY is not set w/ ./arch/arm/Kconfig: select GENERIC_ARCH_TOPOLOGY if ARM_CPU_TOPOLOGY Fixes: ca74b316df96 ("arm: Use common cpu_topology structure and functions") Reviewed-by: Sudeep Holla Reviewed-by: Lukasz Luba Tested-by: Lukasz Luba Tested-by: Ondrej Jirman Signed-off-by: Dietmar Eggemann Signed-off-by: Russell King --- arch/arm/kernel/smp.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'arch/arm/kernel/smp.c') diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index 4b0bab2607e4..46e1be9e57a8 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -240,6 +240,10 @@ int __cpu_disable(void) if (ret) return ret; +#ifdef CONFIG_GENERIC_ARCH_TOPOLOGY + remove_cpu_topology(cpu); +#endif + /* * Take this CPU offline. Once we clear this, we can't return, * and we must not schedule until we're ready to give up the cpu. -- cgit v1.2.3