Messages in this thread | | | Date | Thu, 14 Jul 2022 18:52:49 +0100 | From | Ionela Voinescu <> | Subject | Re: [PATCH -next] arch_topology: Fix cache attributes detection in the CPU hotplug path |
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Hi Sudeep,
Thank you for the fix!
On Wednesday 13 Jul 2022 at 14:33:44 (+0100), Sudeep Holla wrote: > init_cpu_topology() is called only once at the boot and all the cache > attributes are detected early for all the possible CPUs. However when > the CPUs are hotplugged out, the cacheinfo gets removed. While the > attributes are added back when the CPUs are hotplugged back in as part > of CPU hotplug state machine, it ends up called quite late after the > update_siblings_masks() are called in the secondary_start_kernel() > resulting in wrong llc_sibling_masks. > > Move the call to detect_cache_attributes() inside update_siblings_masks() > to ensure the cacheinfo is updated before the LLC sibling masks are > updated. This will fix the incorrect LLC sibling masks generated when > the CPUs are hotplugged out and hotplugged back in again. > > Reported-by: Ionela Voinescu <ionela.voinescu@arm.com> > Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> > --- > drivers/base/arch_topology.c | 16 ++++++---------- > 1 file changed, 6 insertions(+), 10 deletions(-) > > Hi Conor, > > Ionela reported an issue with the CPU hotplug and as a fix I need to > move the call to detect_cache_attributes() which I had thought to keep > it there from first but for no reason had moved it to init_cpu_topology(). > > Wonder if this fixes the -ENOMEM on RISC-V as this one is called on the > cpu in the secondary CPUs init path while init_cpu_topology executed > detect_cache_attributes() for all possible CPUs much earlier. I think > this might help as the percpu memory might be initialised in this case. > > Anyways give this a try, also test the CPU hotplug and check if nothing > is broken on RISC-V. We noticed this bug only on one platform while > > Regards, > Sudeep > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index 441e14ac33a4..0424b59b695e 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -732,7 +732,11 @@ const struct cpumask *cpu_clustergroup_mask(int cpu) > void update_siblings_masks(unsigned int cpuid) > { > struct cpu_topology *cpu_topo, *cpuid_topo = &cpu_topology[cpuid]; > - int cpu; > + int cpu, ret; > + > + ret = detect_cache_attributes(cpuid); > + if (ret) > + pr_info("Early cacheinfo failed, ret = %d\n", ret); > /* update core and thread sibling masks */ > for_each_online_cpu(cpu) { > @@ -821,7 +825,7 @@ __weak int __init parse_acpi_topology(void) > #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) > void __init init_cpu_topology(void) > { > - int ret, cpu; > + int ret; > reset_cpu_topology(); > ret = parse_acpi_topology(); > @@ -836,13 +840,5 @@ void __init init_cpu_topology(void) > reset_cpu_topology(); > return; > } > - > - for_each_possible_cpu(cpu) { > - ret = detect_cache_attributes(cpu); > - if (ret) { > - pr_info("Early cacheinfo failed, ret = %d\n", ret); > - break; > - } > - } > } > #endif > --2.37.1 >
Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com> Tested-by: Ionela Voinescu <ionela.voinescu@arm.com>
Kind regards, Ionela.
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