[report] WARN_ON_ONCE triggered in for_each_sibling_event()

[Zenghui Yu]

Hi folks,

The following splat is triggered when I execute `perf stat -e
smmuv3_pmcg_100020/config_cache_miss/` on mainline kernel (built with
arm64-defconfig + PROVE_LOCKING).

| ------------[ cut here ]------------
| WARNING: CPU: 36 PID: 72452 at drivers/perf/arm_smmuv3_pmu.c:434 
smmu_pmu_event_init+0x298/0x2b0 [arm_smmuv3_pmu]
| Modules linked in: xt_MASQUERADE iptable_nat xt_addrtype xt_conntrack 
nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 libcrc32c overlay 
ip6table_filter ip6_tables xt_tcpudp iptable_filter ip_tables x_tables 
md_mod arm_smmuv3_pmu hibmc_drm drm_vram_helper drm_ttm_helper ttm 
drm_kms_helper spi_dw_mmio spi_dw fuse drm backlight crct10dif_ce 
onboard_usb_hub xhci_pci xhci_pci_renesas hisi_sec2 hisi_qm uacce 
authenc ipmi_si ipmi_devintf ipmi_msghandler dm_mod br_netfilter bridge 
stp llc nvme nvme_core nbd ipv6
| CPU: 36 PID: 72452 Comm: perf Kdump: loaded Not tainted 
6.9.0-rc1-00061-g8d025e2092e2-dirty #1700
| Hardware name: Huawei TaiShan 2280 V2/BC82AMDDA, BIOS 1.05 09/18/2019
| pstate: 80400009 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
| pc : smmu_pmu_event_init+0x298/0x2b0 [arm_smmuv3_pmu]
| lr : smmu_pmu_event_init+0x290/0x2b0 [arm_smmuv3_pmu]
| sp : ffff8000c8ce3be0
| x29: ffff8000c8ce3be0 x28: 0000000000000000 x27: ffff8000802a2c1c
| x26: ffff8000c8ce3d70 x25: ffff8000802a2bc8 x24: 0000000000000000
| x23: 0000000000000001 x22: ffff0028045d52b0 x21: ffff002807228168
| x20: 0000000000000002 x19: ffff002807228000 x18: 0000000000000000
| x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
| x14: 0000000000000000 x13: 0000000000000000 x12: 0000000000000040
| x11: ffff0020804016d0 x10: ffff0020804016d2 x9 : ffff800083b29b18
| x8 : ffff0020804016f8 x7 : 0000000000000000 x6 : ffff0020804018c0
| x5 : ffff0020804016d0 x4 : ffff80007bf07a58 x3 : 0000000000000002
| x2 : ffff802f5db37000 x1 : 0000000000000000 x0 : 0000000000000000
| Call trace:
|  smmu_pmu_event_init+0x298/0x2b0 [arm_smmuv3_pmu]
|  perf_try_init_event+0x54/0x140|  perf_event_alloc+0x3e4/0x1080
|  __do_sys_perf_event_open+0x178/0xfa8
|  __arm64_sys_perf_event_open+0x28/0x34
|  invoke_syscall+0x48/0x114
|  el0_svc_common.constprop.0+0x40/0xe0
|  do_el0_svc+0x1c/0x28
|  el0_svc+0x4c/0x11c
|  el0t_64_sync_handler+0xc0/0xc4
|  el0t_64_sync+0x190/0x194
| irq event stamp: 174338
| hardirqs last  enabled at (174337): [<ffff800080357774>] 
___slab_alloc+0x3bc/0xf38
| hardirqs last disabled at (174338): [<ffff8000812a7ee0>] el1_dbg+0x24/0x8c
| softirqs last  enabled at (174292): [<ffff8000800185bc>] 
fpsimd_restore_current_state+0x34/0xc4
| softirqs last disabled at (174290): [<ffff80008001858c>] 
fpsimd_restore_current_state+0x4/0xc4
| ---[ end trace 0000000000000000 ]---

Note that this is not specific to the arm_smmuv3_pmu driver as I can
also reproduce it with some HiSilicon uncore PMU events (e.g., executing
`perf stat -e hisi_sccl1_ddrc0/flux_rd/`).

For your convenience, the assertion was added by commit f3c0eba28704
("perf: Add a few assertions").

Post it out for visibility, not sure if there are already similar
reports on the list though. Please have a look.

Thanks,
Zenghui