6ba6883648
With the kernel 5.18, the system will hang on boot if it is compiled with CONFIG_SCHED_MC. The last printed message is "Brought up 1 node, 1 CPU". The crash happens in sd_init tl->mask (which is cpu_coregroup_mask) returns an empty mask. This happens because cpu_topology[0].core_sibling is empty. Consequently, sd_span is set to an empty mask sd_id = cpumask_first(sd_span) sets sd_id == NR_CPUS (because the mask is empty) sd->shared = *per_cpu_ptr(sdd->sds, sd_id); sets sd->shared to NULL because sd_id is out of range atomic_inc(&sd->shared->ref); crashes without printing anything We can fix it by calling reset_cpu_topology() from init_cpu_topology() - this will initialize the sibling masks on CPUs, so that they're not empty. This patch also removes the variable "dualcores_found", it is useless, because during boot, init_cpu_topology is called before store_cpu_topology. Thus, set_sched_topology(parisc_mc_topology) is never called. We don't need to call it at all because default_topology in kernel/sched/topology.c contains the same items as parisc_mc_topology. Note that we should not call store_cpu_topology() from init_per_cpu() because it is called too early in the kernel initialization process and it results in the message "Failure to register CPU0 device". Before this patch, store_cpu_topology() would exit immediatelly because cpuid_topo->core id was uninitialized and it was 0. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Cc: stable@vger.kernel.org # v5.18 Signed-off-by: Helge Deller <deller@gmx.de>
88 lines
2.2 KiB
C
88 lines
2.2 KiB
C
/*
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* arch/parisc/kernel/topology.c
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*
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* Copyright (C) 2017 Helge Deller <deller@gmx.de>
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*
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* based on arch/arm/kernel/topology.c
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*/
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#include <linux/percpu.h>
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#include <linux/sched.h>
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#include <linux/sched/topology.h>
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#include <linux/cpu.h>
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#include <asm/topology.h>
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#include <asm/sections.h>
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static DEFINE_PER_CPU(struct cpu, cpu_devices);
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/*
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* store_cpu_topology is called at boot when only one cpu is running
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* and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
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* which prevents simultaneous write access to cpu_topology array
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*/
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void store_cpu_topology(unsigned int cpuid)
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{
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struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
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struct cpuinfo_parisc *p;
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int max_socket = -1;
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unsigned long cpu;
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/* If the cpu topology has been already set, just return */
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if (cpuid_topo->core_id != -1)
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return;
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#ifdef CONFIG_HOTPLUG_CPU
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per_cpu(cpu_devices, cpuid).hotpluggable = 1;
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#endif
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if (register_cpu(&per_cpu(cpu_devices, cpuid), cpuid))
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pr_warn("Failed to register CPU%d device", cpuid);
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/* create cpu topology mapping */
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cpuid_topo->thread_id = -1;
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cpuid_topo->core_id = 0;
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p = &per_cpu(cpu_data, cpuid);
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for_each_online_cpu(cpu) {
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const struct cpuinfo_parisc *cpuinfo = &per_cpu(cpu_data, cpu);
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if (cpu == cpuid) /* ignore current cpu */
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continue;
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if (cpuinfo->cpu_loc == p->cpu_loc) {
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cpuid_topo->core_id = cpu_topology[cpu].core_id;
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if (p->cpu_loc) {
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cpuid_topo->core_id++;
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cpuid_topo->package_id = cpu_topology[cpu].package_id;
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continue;
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}
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}
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if (cpuid_topo->package_id == -1)
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max_socket = max(max_socket, cpu_topology[cpu].package_id);
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}
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if (cpuid_topo->package_id == -1)
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cpuid_topo->package_id = max_socket + 1;
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update_siblings_masks(cpuid);
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pr_info("CPU%u: cpu core %d of socket %d\n",
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cpuid,
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cpu_topology[cpuid].core_id,
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cpu_topology[cpuid].package_id);
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}
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/*
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* init_cpu_topology is called at boot when only one cpu is running
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* which prevent simultaneous write access to cpu_topology array
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*/
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void __init init_cpu_topology(void)
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{
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reset_cpu_topology();
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}
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