Re: Warnings in DRM code when removing/unbinding a driver

[John Garry <john.garry@huawei.com>]

Hi Thomas,

> drm-tip now contains

I have tested today's linux-next, which includes this:

> 
> commit a88248506a2bcfeaef6837a53cde19fe11970e6c
> Author: Thomas Zimmermann <tzimmermann@suse.de>
> Date:   Tue Dec 3 09:38:15 2019 +0100
> 
>      drm/hisilicon/hibmc: Switch to generic fbdev emulation
> 
> which removes this entire code and switches hibmc to generic fbdev
> emulation. Does that fix the problem?
> 

And I see no warn, here's a dmesg snippet:

[   20.672787] pci 0007:90:00.0: can't derive routing for PCI INT A
[   20.678831] hibmc-drm 0007:91:00.0: PCI INT A: no GSI
[   20.686536] pci_bus 0007:90: 2-byte config write to 0007:90:00.0 
offset 0x4 may corrupt adjacent RW1C bits
[   20.696888] [TTM] Zone  kernel: Available graphics memory: 57359458 KiB
[   20.703545] [TTM] Zone   dma32: Available graphics memory: 2097152 KiB
[   20.710108] [TTM] Initializing pool allocator
[   20.714561] [TTM] Initializing DMA pool allocator
[   20.720212] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[   20.726863] [drm] No driver support for vblank timestamp query.
[   20.754777] Console: switching to colour frame buffer device 100x37
[   20.778180] hibmc-drm 0007:91:00.0: fb0: hibmcdrmfb frame buffer device
[   20.786447] [drm] Initialized hibmc 1.0.0 20160828 for 0007:91:00.0 
on minor 0
[   20.794346] Console: switching to colour dummy device 80x25
[   20.801884] pci 0007:90:00.0: can't derive routing for PCI INT A
[   20.807963] hibmc-drm 0007:91:00.0: PCI INT A: no GSI
[   20.813656] [TTM] Finalizing pool allocator
[   20.817905] [TTM] Finalizing DMA pool allocator
[   20.822576] [TTM] Zone  kernel: Used memory at exit: 0 KiB
[   20.828760] [TTM] Zone   dma32: Used memory at exit: 0 KiB
[   20.834978] pci 0007:90:00.0: can't derive routing for PCI INT A
[   20.841021] hibmc-drm 0007:91:00.0: PCI INT A: no GSI
[   20.848858] [TTM] Zone  kernel: Available graphics memory: 57359458 KiB
[   20.855516] [TTM] Zone   dma32: Available graphics memory: 2097152 KiB
[   20.862079] [TTM] Initializing pool allocator
[   20.866525] [TTM] Initializing DMA pool allocator
[   20.872064] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[   20.878716] [drm] No driver support for vblank timestamp query.
[   20.905996] Console: switching to colour frame buffer device 100x37
[   20.929385] hibmc-drm 0007:91:00.0: fb0: hibmcdrmfb frame buffer device
[   20.937241] [drm] Initialized hibmc 1.0.0 20160828 for 0007:91:00.0 
on minor 0
[   21.171906] loop: module loaded

Thanks,
John

> Best regards
> Thomas
> 
>> [   27.965802]  hibmc_unload+0x2c/0xd0
>> [   27.969281]  hibmc_pci_remove+0x2c/0x40
>> [   27.973109]  pci_device_remove+0x6c/0x140
>> [   27.977110]  really_probe+0x174/0x548
>> [   27.980763]  driver_probe_device+0x7c/0x148
>> [   27.984936]  device_driver_attach+0x94/0xa0
>> [   27.989109]  __driver_attach+0xa8/0x110
>> [   27.992935]  bus_for_each_dev+0xe8/0x158
>> [   27.996849]  driver_attach+0x30/0x40
>> [   28.000415]  bus_add_driver+0x234/0x2f0
>> [   28.004241]  driver_register+0xbc/0x1d0
>> [   28.008067]  __pci_register_driver+0xbc/0xd0
>> [   28.012329]  hibmc_pci_driver_init+0x20/0x28
>> [   28.016590]  do_one_initcall+0xb4/0x254
>> [   28.020417]  kernel_init_freeable+0x27c/0x328
>> [   28.024765]  kernel_init+0x10/0x118
>> [   28.028245]  ret_from_fork+0x10/0x18
>> [   28.031813] ---[ end trace 35a83b71b657878d ]---
>> [   28.036503] ------------[ cut here ]------------
>> [   28.041115] WARNING: CPU: 24 PID: 1 at
>> drivers/gpu/drm/drm_gem_vram_helper.c:40
>> ttm_buffer_object_destroy+0x4c/0x80
>> [   28.051537] Modules linked in:
>> [   28.054585] CPU: 24 PID: 1 Comm: swapper/0 Tainted: G    B   W
>>   5.5.0-rc1-dirty #565
>> [   28.062924] Hardware name: Huawei D06 /D06, BIOS Hisilicon D06 UEFI
>> RC0 - V1.16.01 03/15/2019
>>
>> [snip]
>>
>> Indeed, simply unbinding the device from the driver causes the same sort
>> of issue:
>>
>> root@(none)$ cd ./bus/pci/drivers/hibmc-drm/
>> root@(none)$ ls
>> 0000:05:00.0  bind          new_id        remove_id     uevent
>> unbind
>> root@(none)$ echo 0000\:05\:00.0 > unbind
>> [  116.074352] ------------[ cut here ]------------
>> [  116.078978] WARNING: CPU: 17 PID: 1178 at
>> drivers/gpu/drm/drm_gem_vram_helper.c:40
>> ttm_buffer_object_destroy+0x4c/0x80
>> [  116.089661] Modules linked in:
>> [  116.092711] CPU: 17 PID: 1178 Comm: sh Tainted: G    B   W
>> 5.5.0-rc1-dirty #565
>> [  116.100704] Hardware name: Huawei D06 /D06, BIOS Hisilicon D06 UEFI
>> RC0 - V1.16.01 03/15/2019
>> [  116.109218] pstate: 20400009 (nzCv daif +PAN -UAO)
>> [  116.114001] pc : ttm_buffer_object_destroy+0x4c/0x80
>> [  116.118956] lr : ttm_buffer_object_destroy+0x18/0x80
>> [  116.123910] sp : ffff0022e6cef8e0
>> [  116.127215] x29: ffff0022e6cef8e0 x28: ffff00231b1fb000
>> [  116.132519] x27: 0000000000000000 x26: ffff00231b1fb000
>> [  116.137821] x25: ffff0022e6cefdc0 x24: 0000000000002480
>> [  116.143124] x23: ffff0023682b6ab0 x22: ffff0023682b6800
>> [  116.148427] x21: ffff0023682b6800 x20: 0000000000000000
>> [  116.153730] x19: ffff0023682b6800 x18: 0000000000000000
>> [  116.159032] x17: 000000000000000000000000001
>> [  116.185545] x7 : ffff0023682b6b07 x6 : ffff80046d056d61
>> [  116.190848] x5 : ffff80046d056d61 x4 : ffff0023682b6ba0
>> [  116.196151] x3 : ffffa00010197338 x2 : dfffa00000000000
>> [  116.201453] x1 : 0000000000000003 x0 : 0000000000000001
>> [  116.206756] Call trace:
>> [  116.209195]  ttm_buffer_object_destroy+0x4c/0x80
>> [  116.213803]  ttm_bo_release_list+0x184/0x220
>> [  116.218064]  ttm_bo_put+0x410/0x5d0
>> [  116.221544]  drm_gem_vram_object_free+0xc/0x18
>> [  116.225979]  drm_gem_object_free+0x34/0xd0
>> [  116.230066]  drm_gem_object_put_unlocked+0xc8/0xf0
>> [  116.234848]  hibmc_user_framebuffer_destroy+0x20/0x40
>> [  116.239890]  drm_framebuffer_free+0x48/0x58
>> [  116.244064]  drm_mode_object_put.part.1+0x90/0xe8
>> [  116.248759]  drm_mode_object_put+0x28/0x38
>> [  116.252846]  hibmc_fbdev_fini+0x54/0x78
>> [  116.256672]  hibmc_unload+0x2c/0xd0
>> [  116.260151]  hibmc_pci_remove+0x2c/0x40
>> [  116.263979]  pci_device_remove+0x6c/0x140
>> [  116.267980]  device_release_driver_internal+0x134/0x250
>> [  116.273196]  device_driver_detach+0x28/0x38
>> [  116.277369]  unbind_store+0xfc/0x150
>> [  116.280934]  drv_attr_store+0x48/0x60
>> [  116.284589]  sysfs_kf_write+0x80/0xb0
>> [  116.288241]  kernfs_fop_write+0x1d4/0x320
>> [  116.292243]  __vfs_write+0x54/0x98
>> [  116.295635]  vfs_write+0xe8/0x270
>> [  116.298940]  ksys_write+0xc8/0x180
>> [  116.302333]  __arm64_sys_write+0x40/0x50
>> [  116.306248]  el0_svc_common.constprop.0+0xa4/0x1f8
>> [  116.311029]  el0_svc_handler+0x34/0xb0
>> [  116.314770]  el0_sync_handler+0x10c/0x1c8
>> [  116.318769]  el0_sync+0x140/0x180
>> [  116.322074] ---[ end trace e60e43d0e316b5c8 ]---
>> [  116.326868] ------------[ cut here ]------------
>>
>>
>> dmesg and .config is here:
>> https://pastebin.com/4P5yaZBS
>>
>> I'm not sure if this is a HIBMC driver issue or issue with the framework.
>>
>> john
>>
>>
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>