lkml.org 
[lkml]   [2020]   [Jul]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling
From
Date
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.

\
 
 \ /
  Last update: 2020-07-16 12:38    [W:0.167 / U:0.276 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site