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author | Mikulas Patocka <mpatocka@redhat.com> | 2022-06-01 13:18:22 -0400 |
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committer | Helge Deller <deller@gmx.de> | 2022-06-03 09:54:01 +0200 |
commit | 6ba688364856ad083be537f08e86ba97f433d405 (patch) | |
tree | 4c9e7b5878038a1b6b6f10703a70eb5cfe91fc0e /arch | |
parent | 4b0986a3613c92f4ec1bdc7f60ec66fea135991f (diff) | |
download | linux-stable-6ba688364856ad083be537f08e86ba97f433d405.tar.gz linux-stable-6ba688364856ad083be537f08e86ba97f433d405.tar.bz2 linux-stable-6ba688364856ad083be537f08e86ba97f433d405.zip |
parisc: fix a crash with multicore scheduler
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>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/parisc/kernel/processor.c | 2 | ||||
-rw-r--r-- | arch/parisc/kernel/topology.c | 16 |
2 files changed, 1 insertions, 17 deletions
diff --git a/arch/parisc/kernel/processor.c b/arch/parisc/kernel/processor.c index 26eb568f8b96..dddaaa6e7a82 100644 --- a/arch/parisc/kernel/processor.c +++ b/arch/parisc/kernel/processor.c @@ -327,8 +327,6 @@ int init_per_cpu(int cpunum) set_firmware_width(); ret = pdc_coproc_cfg(&coproc_cfg); - store_cpu_topology(cpunum); - if(ret >= 0 && coproc_cfg.ccr_functional) { mtctl(coproc_cfg.ccr_functional, 10); /* 10 == Coprocessor Control Reg */ diff --git a/arch/parisc/kernel/topology.c b/arch/parisc/kernel/topology.c index 9696e3cb6a2a..b9d845e314f8 100644 --- a/arch/parisc/kernel/topology.c +++ b/arch/parisc/kernel/topology.c @@ -20,8 +20,6 @@ static DEFINE_PER_CPU(struct cpu, cpu_devices); -static int dualcores_found; - /* * store_cpu_topology is called at boot when only one cpu is running * and with the mutex cpu_hotplug.lock locked, when several cpus have booted, @@ -60,7 +58,6 @@ void store_cpu_topology(unsigned int cpuid) if (p->cpu_loc) { cpuid_topo->core_id++; cpuid_topo->package_id = cpu_topology[cpu].package_id; - dualcores_found = 1; continue; } } @@ -80,22 +77,11 @@ void store_cpu_topology(unsigned int cpuid) cpu_topology[cpuid].package_id); } -static struct sched_domain_topology_level parisc_mc_topology[] = { -#ifdef CONFIG_SCHED_MC - { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) }, -#endif - - { cpu_cpu_mask, SD_INIT_NAME(DIE) }, - { NULL, }, -}; - /* * init_cpu_topology is called at boot when only one cpu is running * which prevent simultaneous write access to cpu_topology array */ void __init init_cpu_topology(void) { - /* Set scheduler topology descriptor */ - if (dualcores_found) - set_sched_topology(parisc_mc_topology); + reset_cpu_topology(); } |