Re: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling

[Will Deacon]

On Thu, 16 Jul 2020 17:19:25 +0800, Qi Liu wrote:
> When users try to remove PMU modules during perf sampling, kernel panic
> will happen because the pmu->read() is a NULL pointer here.
> 
> INFO on HiSilicon hip08 platform as follow:
> pc : hisi_uncore_pmu_event_update+0x30/0xa4 [hisi_uncore_pmu]
> lr : hisi_uncore_pmu_read+0x20/0x2c [hisi_uncore_pmu]
> sp : ffff800010103e90
> x29: ffff800010103e90 x28: ffff0027db0c0e40
> x27: ffffa29a76f129d8 x26: ffffa29a77ceb000
> x25: ffffa29a773a5000 x24: ffffa29a77392000
> x23: ffffddffe5943f08 x22: ffff002784285960
> x21: ffff002784285800 x20: ffff0027d2e76c80
> x19: ffff0027842859e0 x18: ffff80003498bcc8
> x17: ffffa29a76afe910 x16: ffffa29a7583f530
> x15: 16151a1512061a1e x14: 0000000000000000
> x13: ffffa29a76f1e238 x12: 0000000000000001
> x11: 0000000000000400 x10: 00000000000009f0
> x9 : ffff8000107b3e70 x8 : ffff0027db0c1890
> x7 : ffffa29a773a7000 x6 : 00000007f5131013
> x5 : 00000007f5131013 x4 : 09f257d417c00000
> x3 : 00000002187bd7ce x2 : ffffa29a38f0f0d8
> x1 : ffffa29a38eae268 x0 : ffff0027d2e76c80
> Call trace:
> hisi_uncore_pmu_event_update+0x30/0xa4 [hisi_uncore_pmu]
> hisi_uncore_pmu_read+0x20/0x2c [hisi_uncore_pmu]
> __perf_event_read+0x1a0/0x1f8
> flush_smp_call_function_queue+0xa0/0x160
> generic_smp_call_function_single_interrupt+0x18/0x20
> handle_IPI+0x31c/0x4dc
> gic_handle_irq+0x2c8/0x310
> el1_irq+0xcc/0x180
> arch_cpu_idle+0x4c/0x20c
> default_idle_call+0x20/0x30
> do_idle+0x1b4/0x270
> cpu_startup_entry+0x28/0x30
> secondary_start_kernel+0x1a4/0x1fc
> 
> [...]

Applied to arm64 (for-next/fixes), thanks!

[1/1] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling
      https://git.kernel.org/arm64/c/bdc5c744c7b6

Cheers,
-- 
Will

https://fixes.arm64.dev
https://next.arm64.dev
https://will.arm64.dev