When hot adding a CPU and onlining it, the following WARN_ON() messages are shown:
[ 772.891448] ------------[ cut here ]------------ [ 772.896624] WARNING: CPU: 58 PID: 15169 at arch/x86/kernel/cpu/perf_event_intel_cqm.c:1268 intel_cqm_cpu_prepare+0x88/0x90() [ 772.909167] Modules linked in: [ 772.995134] CPU: 58 PID: 15169 [ 773.016633] 0000000000000000 0000000092fb60ed ffff88104febbba8 ffffffff8167b5fa [ 773.024789] 0000000000000000 0000000000000000 ffff88104febbbe8 ffffffff810819ea [ 773.033119] ffff88103be60000 ffff8c0fbc7ca020 ffffffff819fadf0 000000000000008f [ 773.041461] Call Trace: [ 773.044402] [<ffffffff8167b5fa>] dump_stack+0x45/0x57 [ 773.050160] [<ffffffff810819ea>] warn_slowpath_common+0x8a/0xc0 [ 773.056888] [<ffffffff81081b1a>] warn_slowpath_null+0x1a/0x20 [ 773.063426] [<ffffffff810365f8>] intel_cqm_cpu_prepare+0x88/0x90 [ 773.070253] [<ffffffff81036732>] intel_cqm_cpu_notifier+0x42/0x160 [ 773.077271] [<ffffffff810a0d3d>] notifier_call_chain+0x4d/0x80 [ 773.083901] [<ffffffff810a0e4e>] __raw_notifier_call_chain+0xe/0x10 [ 773.091007] [<ffffffff81081ef8>] _cpu_up+0xe8/0x190 [ 773.096555] [<ffffffff8108201a>] cpu_up+0x7a/0xa0 [ 773.101910] [<ffffffff816701b0>] cpu_subsys_online+0x40/0x90 [ 773.108332] [<ffffffff8143d777>] device_online+0x67/0x90 [ 773.114368] [<ffffffff8143d82a>] online_store+0x8a/0xa0 [ 773.120305] [<ffffffff8143aab8>] dev_attr_store+0x18/0x30 [ 773.126437] [<ffffffff8127224a>] sysfs_kf_write+0x3a/0x50 [ 773.132560] [<ffffffff812718d0>] kernfs_fop_write+0x120/0x170 [ 773.139078] [<ffffffff811f7657>] __vfs_write+0x37/0x100 [ 773.145019] [<ffffffff811fa398>] ? __sb_start_write+0x58/0x110 [ 773.151635] [<ffffffff8129d7ed>] ? security_file_permission+0x3d/0xc0 [ 773.158932] [<ffffffff811f7d59>] vfs_write+0xa9/0x190 [ 773.164674] [<ffffffff810234e6>] ? do_audit_syscall_entry+0x66/0x70 [ 773.171776] [<ffffffff811f8b55>] SyS_write+0x55/0xc0 [ 773.177423] [<ffffffff810672f0>] ? do_page_fault+0x30/0x80 [ 773.183654] [<ffffffff8168232e>] entry_SYSCALL_64_fastpath+0x12/0x71 [ 773.190843] ---[ end trace e6219d24386873bd ]--- [ 773.196573] smpboot: Booting Node 7 Processor 143 APIC 0x1f7 [ 773.221241] microcode: CPU143 sig=0x306f3, pf=0x80, revision=0x9 [ 773.228005] Will online and init hotplugged CPU: 143 Here is the root cause of the issue: When calling intel_cqm_cpu_prepare() at CPU_UP_PREPARE notification, the function checks that c86_chache_max_rmid is same as cqm_max_rmid as follows: static void intel_cqm_cpu_prepare(unsigned int cpu) { ... WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid); But x86_cache_max_rmid of hot added CPU is not set yet, because it will set in get_cpu_cap() which is called after CPU_UP_PREPARE notification. So when onlining a hot added CPU, the WARN_ON() are always shown: To fix the issue, the patch moves WARN_ON()s from intel_cqm_cpu_prepare() to cqm_pick_event_reader() which is called at CPU_STARTING notification. Signed-off-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com> CC: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Vikas Shivappa <vikas.shiva...@intel.com> Cc: Kanaka Juvva <kanaka.d.ju...@intel.com> CC: Matt Fleming <matt.flem...@intel.com> --- arch/x86/kernel/cpu/perf_event_intel_cqm.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/perf_event_intel_cqm.c b/arch/x86/kernel/cpu/perf_event_intel_cqm.c index 63eb68b..6196d3e 100644 --- a/arch/x86/kernel/cpu/perf_event_intel_cqm.c +++ b/arch/x86/kernel/cpu/perf_event_intel_cqm.c @@ -1244,9 +1244,13 @@ static struct pmu intel_cqm_pmu = { static inline void cqm_pick_event_reader(int cpu) { + struct cpuinfo_x86 *c = &cpu_data(cpu); int phys_id = topology_physical_package_id(cpu); int i; + WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid); + WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale); + for_each_cpu(i, &cqm_cpumask) { if (phys_id == topology_physical_package_id(i)) return; /* already got reader for this socket */ @@ -1258,14 +1262,10 @@ static inline void cqm_pick_event_reader(int cpu) static void intel_cqm_cpu_prepare(unsigned int cpu) { struct intel_pqr_state *state = &per_cpu(pqr_state, cpu); - struct cpuinfo_x86 *c = &cpu_data(cpu); state->rmid = 0; state->closid = 0; state->rmid_usecnt = 0; - - WARN_ON(c->x86_cache_max_rmid != cqm_max_rmid); - WARN_ON(c->x86_cache_occ_scale != cqm_l3_scale); } static void intel_cqm_cpu_exit(unsigned int cpu) -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/