Re: arm64: Internal error: Oops: qcom_iommu_tlb_inv_context free_io_pgtable_ops on db410c

[Robin Murphy <robin.murphy@arm.com>]

On 2020-07-20 08:17, Arnd Bergmann wrote:
> On Mon, Jul 20, 2020 at 8:36 AM Naresh Kamboju
> <naresh.kamboju@linaro.org> wrote:
>>
>> This kernel oops while boot linux mainline kernel on arm64  db410c device.
>>
>> metadata:
>>    git branch: master
>>    git repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>    git commit: f8456690ba8eb18ea4714e68554e242a04f65cff
>>    git describe: v5.8-rc5-48-gf8456690ba8e
>>    make_kernelversion: 5.8.0-rc5
>>    kernel-config:
>> https://builds.tuxbuild.com/2aLnwV7BLStU0t1R1QPwHQ/kernel.config
> 
> Thanks for the report. Adding freedreno folks to Cc, as this may have something
> to do with that driver.
> 
>>
>> [    5.444121] Unable to handle kernel NULL pointer dereference at
>> virtual address 0000000000000018
>> [    5.456615]   ESR = 0x96000004
>> [    5.464471]   SET = 0, FnV = 0
>> [    5.464487]   EA = 0, S1PTW = 0
>> [    5.466521] Data abort info:
>> [    5.469971]   ISV = 0, ISS = 0x00000004
>> [    5.472768]   CM = 0, WnR = 0
>> [    5.476172] user pgtable: 4k pages, 48-bit VAs, pgdp=00000000bacba000
>> [    5.479349] [0000000000000018] pgd=0000000000000000, p4d=0000000000000000
>> [    5.485820] Internal error: Oops: 96000004 [#1] PREEMPT SMP
>> [    5.492448] Modules linked in: crct10dif_ce adv7511(+)
>> qcom_spmi_temp_alarm cec msm(+) mdt_loader qcom_camss videobuf2_dma_sg
>> drm_kms_helper v4l2_fwnode videobuf2_memops videobuf2_v4l2 qcom_rng
>> videobuf2_common i2c_qcom_cci display_connector socinfo drm qrtr ns
>> rmtfs_mem fuse
>> [    5.500256] CPU: 0 PID: 286 Comm: systemd-udevd Not tainted 5.8.0-rc5 #1
>> [    5.522484] Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
>> [    5.529170] pstate: 20000005 (nzCv daif -PAN -UAO BTYPE=--)
>> [    5.535856] pc : qcom_iommu_tlb_inv_context+0x18/0xa8
>> [    5.541148] lr : free_io_pgtable_ops+0x28/0x58
>> [    5.546350] sp : ffff80001219b5f0
>> [    5.550689] x29: ffff80001219b5f0 x28: 0000000000000013
>> [    5.554078] x27: 0000000000000100 x26: ffff000036add3b8
>> [    5.559459] x25: ffff80000915e910 x24: ffff00003a5458c0
>> [    5.564753] x23: 0000000000000003 x22: ffff000036a37058
>> [    5.570049] x21: ffff000036a3a100 x20: ffff000036a3a480
>> [    5.575344] x19: ffff000036a37158 x18: 0000000000000000
>> [    5.580639] x17: 0000000000000000 x16: 0000000000000000
>> [    5.585935] x15: 0000000000000004 x14: 0000000000000368
>> [    5.591229] x13: 0000000000000000 x12: ffff000039c61798
>> [    5.596525] x11: ffff000039c616d0 x10: 0000000040000000
>> [    5.601820] x9 : 0000000000000000 x8 : ffff000039c616f8
>> [    5.607114] x7 : 0000000000000000 x6 : ffff000009f699a0
>> [    5.612410] x5 : ffff80001219b520 x4 : ffff000036a3a000
>> [    5.617705] x3 : ffff000009f69904 x2 : 0000000000000000
>> [    5.623001] x1 : ffff8000107e27e8 x0 : ffff00003a545810
>> [    5.628297] Call trace:
>> [    5.633592]  qcom_iommu_tlb_inv_context+0x18/0xa8
> 
> This means that dev_iommu_fwspec_get() has returned NULL
> in qcom_iommu_tlb_inv_context(), either because dev->iommu
> is NULL, or because dev->iommu->fwspec is NULL.
> 
> qcom_iommu_tlb_inv_context() does not check for a NULL
> pointer before using the returned object.
> 
> The bug is either in the lack of error handling, or the fact
> that it's possible to get into this function for a device
> that has not been fully set up.

Not quite - the device *was* properly set up, but has already been 
properly torn down again in the removal path by iommu_release_device(). 
The problem is that qcom-iommu kept the device pointer as its TLB cookie 
for the domain, but the domain has a longer lifespan than the validity 
of that device - that's a fundamental design flaw in the driver.

Robin.

>> [    5.635764]  free_io_pgtable_ops+0x28/0x58
>> [    5.640624]  qcom_iommu_domain_free+0x38/0x60
>> [    5.644617]  iommu_group_release+0x4c/0x70
>> [    5.649045]  kobject_put+0x6c/0x120
>> [    5.653035]  kobject_del+0x64/0x90
>> [    5.656421]  kobject_put+0xfc/0x120
>> [    5.659893]  iommu_group_remove_device+0xdc/0xf0
>> [    5.663281]  iommu_release_device+0x44/0x70
>> [    5.668142]  iommu_bus_notifier+0xbc/0xd0
>> [    5.672048]  notifier_call_chain+0x54/0x98
>> [    5.676214]  blocking_notifier_call_chain+0x48/0x70
>> [    5.680209]  device_del+0x26c/0x3a0
>> [    5.684981]  platform_device_del.part.0+0x1c/0x88
>> [    5.688453]  platform_device_unregister+0x24/0x40
>> [    5.693316]  of_platform_device_destroy+0xe4/0xf8
>> [    5.698002]  device_for_each_child+0x5c/0xa8
>> [    5.702689]  of_platform_depopulate+0x3c/0x80
>> [    5.707144]  msm_pdev_probe+0x1c4/0x308 [msm]
> 
> It was triggered by a failure in msm_pdev_probe(), which was
> calls of_platform_depopulate() in its error handling code.
> This is a combination of two problems:
> 
> a) Whatever caused msm_pdev_probe() to fail means that
> the gpu won't be usable, though it should not have caused the
> kernel to crash.
> 
> b) the error handling itself causing additional problems due
> to failed unwinding.
> 
>> [    5.711286]  platform_drv_probe+0x54/0xa8
>> [    5.715624]  really_probe+0xd8/0x320
>> [    5.719617]  driver_probe_device+0x58/0xb8
>> [    5.723263]  device_driver_attach+0x74/0x80
>> [    5.727168]  __driver_attach+0x58/0xe0
>> [    5.731248]  bus_for_each_dev+0x70/0xc0
>> [    5.735067]  driver_attach+0x24/0x30
>> [    5.738801]  bus_add_driver+0x14c/0x1f0
>> [    5.742619]  driver_register+0x64/0x120
>> [    5.746178]  __platform_driver_register+0x48/0x58
>> [    5.750099]  msm_drm_register+0x58/0x70 [msm]
>> [    5.754861]  do_one_initcall+0x54/0x1a0
>> [    5.759200]  do_init_module+0x54/0x200
>> [    5.762846]  load_module+0x1d1c/0x2300
>> [    5.766664]  __do_sys_finit_module+0xd8/0xf0
>> [    5.770398]  __arm64_sys_finit_module+0x20/0x30
>> [    5.774826]  el0_svc_common.constprop.0+0x6c/0x168
>> [    5.779078]  do_el0_svc+0x24/0x90
>> [    5.783939]  el0_sync_handler+0x90/0x198
>> [    5.787323]  el0_sync+0x158/0x180
>> [    5.791323] Code: 910003fd f9417404 b4000484 f9401482 (b9401846)
>> [    5.794532] ---[ end trace 3d6a53241629e560 ]---
>>
>> full crash log details.
>> https://qa-reports.linaro.org/lkft/linux-mainline-oe/build/v5.8-rc5-48-gf8456690ba8e/testrun/2945157/suite/linux-log-parser/test/check-kernel-oops-1573988/log
> 
> There are a couple of messages directly preceding the bug output that are
> probably relevant here:
> 
> [    5.259499] debugfs: Directory '1b0ac00.camss-vdda' with parent
> 'smd:rpm:rpm-requests:pm8916-regulators-l2' already present!
>           Starting Resize root filesystem to fit available disk space...
>           Starting Start the WCN core...
> [[0;32m  OK  [0m] Started Network Service.
> [[0;32m  OK  [0m] Started QRTR service.
> [    5.352993] adreno 1c00000.gpu: Adding to iommu group 1
> [    5.357489] msm_mdp 1a01000.mdp: Adding to iommu group 2
> [    5.357757] msm_mdp 1a01000.mdp: No interconnect support may cause
> display underflows!
> [    5.366215] adv7511 3-0039: supply dvdd not found, using dummy regulator
> [    5.378036] msm 1a00000.mdss: supply vdd not found, using dummy regulator
> [    5.378715] msm_mdp 1a01000.mdp: [drm:mdp5_bind [msm]] MDP5 version v1.6
> [    5.380549] adv7511 3-0039: supply pvdd not found, using dummy regulator
> [    5.384606] msm 1a00000.mdss: bound 1a01000.mdp (ops mdp5_ops [msm])
> [    5.394368] adv7511 3-0039: supply a2vdd not found, using dummy regulator
> [    5.397633] msm_dsi 1a98000.dsi: supply gdsc not found, using dummy regulator
> [    5.411897] msm_dsi 1a98000.dsi: supply gdsc not found, using dummy regulator
> [    5.420207] msm_dsi_manager_register: failed to register mipi dsi
> host for DSI 0
> [    5.425717] platform 1a01000.mdp: Removing from iommu group 2
> [[0;1;31mFAILED[0m] Failed to start Entropy Daemon based on the HAVEGE
> algorithm.[    5.444121] Unable to handle kernel NULL pointer
> dereference at virtual address 0000000000000018
> 
> See 'systemctl status haveged.service' for detai[    5.456615]   ESR =
> 0x96000004
> ls.
> [    5.464471]   SET = 0, FnV = 0
> [    5.464487]   EA = 0, S1PTW = 0
> 
>          Arnd
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