Messages in this thread | | | Date | Wed, 3 Apr 2024 10:48:27 +0100 | From | Mark Rutland <> | Subject | Re: [report] WARN_ON_ONCE triggered in for_each_sibling_event() |
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On Thu, Mar 28, 2024 at 06:06:21PM +0800, Zenghui Yu wrote: > Hi folks,
Hi Zenghui,
> 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 for the report!
This is indeed a regression caused by commit:
f3c0eba28704 ("perf: Add a few assertions")
.. and it's concerning that we haven't had a report until now; we're clearly not testing system/uncore PMUs all that much. :/
I don't want to remove the assertion, since that will catch missed locking that has been the source of a number of nasty bugs.
I think we have to update all PMU drivers to avoid for_each_sibling_event() when event == group_leader. That's the established practice in CPU PMU drivers, and with that done I believe that we can tighten the requirements such that for_each_sibling_event() can *only* be called for a group leader, which would catch unintentional misuse in the core code.
Looking around, I see some other (related) problems in group validation in some PMU drivers, so I'll spin a series to address those in one go. I'll try to get that out in the next few days.
Mark.
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