Messages in this thread Patch in this message | | | Subject | Re: [PATCH] powerpc/perf: Fix core-imc hotplug callback failure during imc initialization | From | Anju T Sudhakar <> | Date | Thu, 2 Nov 2017 14:18:48 +0530 |
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Hi,
On Wednesday 01 November 2017 06:22 AM, Michael Ellerman wrote: > Anju T Sudhakar <anju@linux.vnet.ibm.com> writes: > >> Call trace observed during boot: > What's the actual oops?
The actual oops is:
[ 0.750749] PCI: CLS 0 bytes, default 128 [ 0.750855] Unpacking initramfs... [ 1.570445] Freeing initrd memory: 23168K [ 1.571090] rtas_flash: no firmware flash support [ 1.573873] nest_capp0_imc performance monitor hardware support registered [ 1.574006] nest_capp1_imc performance monitor hardware support registered [ 1.579616] core_imc memory allocation for cpu 56 failed [ 1.579730] Unable to handle kernel paging request for data at address 0xffa400010 [ 1.579797] Faulting instruction address: 0xc000000000bf3294 0:mon> e cpu 0x0: Vector: 300 (Data Access) at [c000000ff38ff8d0] pc: c000000000bf3294: mutex_lock+0x34/0x90 lr: c000000000bf3288: mutex_lock+0x28/0x90 sp: c000000ff38ffb50 msr: 9000000002009033 dar: ffa400010 dsisr: 80000 current = 0xc000000ff383de00 paca = 0xc000000007ae0000 softe: 0 irq_happened: 0x01 pid = 13, comm = cpuhp/0 Linux version 4.11.0-39.el7a.ppc64le (mockbuild@ppc-058.build.eng.bos.redhat.com) (gcc version 4.8.5 20150623 (Red Hat 4.8.5-16) (GCC) ) #1 SMP Tue Oct 3 07:42:44 EDT 2017 0:mon> t [c000000ff38ffb80] c0000000002ddfac perf_pmu_migrate_context+0xac/0x470 [c000000ff38ffc40] c00000000011385c ppc_core_imc_cpu_offline+0x1ac/0x1e0 [c000000ff38ffc90] c000000000125758 cpuhp_invoke_callback+0x198/0x5d0 [c000000ff38ffd00] c00000000012782c cpuhp_thread_fun+0x8c/0x3d0 [c000000ff38ffd60] c0000000001678d0 smpboot_thread_fn+0x290/0x2a0 [c000000ff38ffdc0] c00000000015ee78 kthread+0x168/0x1b0 [c000000ff38ffe30] c00000000000b368 ret_from_kernel_thread+0x5c/0x74
>> [c000000ff38ffb80] c0000000002ddfac perf_pmu_migrate_context+0xac/0x470 >> [c000000ff38ffc40] c00000000011385c ppc_core_imc_cpu_offline+0x1ac/0x1e0 >> [c000000ff38ffc90] c000000000125758 cpuhp_invoke_callback+0x198/0x5d0 >> [c000000ff38ffd00] c00000000012782c cpuhp_thread_fun+0x8c/0x3d0 >> [c000000ff38ffd60] c0000000001678d0 smpboot_thread_fn+0x290/0x2a0 >> [c000000ff38ffdc0] c00000000015ee78 kthread+0x168/0x1b0 >> [c000000ff38ffe30] c00000000000b368 ret_from_kernel_thread+0x5c/0x74 >> >> While registering the cpuhoplug callbacks for core-imc, if we fails >> in the cpuhotplug online path for any random core (either because opal call to >> initialize the core-imc counters fails or because memory allocation fails for >> that core), ppc_core_imc_cpu_offline() will get invoked for other cpus who >> successfully returned from cpuhotplug online path. >> >> But in the ppc_core_imc_cpu_offline() path we are trying to migrate the event >> context, when core-imc counters are not even initialized. Thus creating the >> above stack dump. >> >> Add a check to see if core-imc counters are enabled or not in the cpuhotplug >> offline path before migrating the context to handle this failing scenario. > Why do we need a bool to track this? Can't we just check the data > structure we're deinitialising has been initialised? > > Doesn't this also mean we won't cleanup the initialisation for any CPUs > that have been initialised? we do the cleanup in the failing case.
Thanks for the review.
Thanks, Anju
> cheers > >> diff --git a/arch/powerpc/perf/imc-pmu.c b/arch/powerpc/perf/imc-pmu.c >> index 8812624..08139f9 100644 >> --- a/arch/powerpc/perf/imc-pmu.c >> +++ b/arch/powerpc/perf/imc-pmu.c >> @@ -30,6 +30,7 @@ static struct imc_pmu *per_nest_pmu_arr[IMC_MAX_PMUS]; >> static cpumask_t nest_imc_cpumask; >> struct imc_pmu_ref *nest_imc_refc; >> static int nest_pmus; >> +static bool core_imc_enabled; >> >> /* Core IMC data structures and variables */ >> >> @@ -607,6 +608,19 @@ static int ppc_core_imc_cpu_offline(unsigned int cpu) >> if (!cpumask_test_and_clear_cpu(cpu, &core_imc_cpumask)) >> return 0; >> >> + /* >> + * See if core imc counters are enabled or not. >> + * >> + * Suppose we reach here from core_imc_cpumask_init(), >> + * since we failed at the cpuhotplug online path for any random >> + * core (either because opal call to initialize the core-imc counters >> + * failed or because memory allocation failed). >> + * We need to check whether core imc counters are enabled or not before >> + * migrating the event context from cpus in the other cores. >> + */ >> + if (!core_imc_enabled) >> + return 0; >> + >> /* Find any online cpu in that core except the current "cpu" */ >> ncpu = cpumask_any_but(cpu_sibling_mask(cpu), cpu); >> >> @@ -1299,6 +1313,7 @@ int init_imc_pmu(struct device_node *parent, struct imc_pmu *pmu_ptr, int pmu_id >> return ret; >> } >> >> + core_imc_enabled = true; >> break; >> case IMC_DOMAIN_THREAD: >> ret = thread_imc_cpu_init(); >> -- >> 2.7.4
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