Messages in this thread | | | Subject | Re: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling | From | John Garry <> | Date | Thu, 16 Jul 2020 11:36:10 +0100 |
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On 16/07/2020 11:30, Will Deacon wrote: > On Thu, Jul 16, 2020 at 11:26:25AM +0100, Robin Murphy wrote: >> On 2020-07-16 10:41, Will Deacon wrote: >>> On Thu, Jul 16, 2020 at 05:19:25PM +0800, Qi Liu wrote: >>>> Kernel panic will also happen when users try to unbind PMU drivers with >>>> device. This unbind issue could be solved by another patch latter. >>>> >>>> drivers/perf/arm_smmuv3_pmu.c | 1 + >>>> drivers/perf/fsl_imx8_ddr_perf.c | 1 + >>>> drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c | 1 + >>>> drivers/perf/hisilicon/hisi_uncore_hha_pmu.c | 1 + >>>> drivers/perf/hisilicon/hisi_uncore_l3c_pmu.c | 1 + >>>> 5 files changed, 5 insertions(+) >>>> >>>> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c >>>> index 48e28ef..90caba56 100644 >>>> --- a/drivers/perf/arm_smmuv3_pmu.c >>>> +++ b/drivers/perf/arm_smmuv3_pmu.c >>>> @@ -742,6 +742,7 @@ static int smmu_pmu_probe(struct platform_device *pdev) >>>> platform_set_drvdata(pdev, smmu_pmu); >>>> >>>> smmu_pmu->pmu = (struct pmu) { >>>> + .module = THIS_MODULE, >>> I thought platform_driver_register() did this automatically? >> For the platform device itself, yes, but this is for the PMU device - perf >> needs to take a reference to the module, otherwise the platform device can >> still be pulled out from under its feet. > Urgh, gross. > >> I can't remember if we ever discussed making perf_pmu_register() do the same >> trick as platform_device_register() and friends, but obviously it's a >> possibility. > Yeah, but I suppose this patch is the right thing to do for now. I'll queue > it as a fix. >
Please also note what Qi Liu wrote about being able to unbind the driver and cause the same issue. I don't know if you can about that issue also.
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