Warnings in DRM code when removing/unbinding a driver

From: John Garry
Date: Mon Dec 16 2019 - 12:23:22 EST

Hi all,

Enabling CONFIG_DEBUG_TEST_DRIVER_REMOVE causes many warns on a system with the HIBMC hw:

[ 27.788806] WARNING: CPU: 24 PID: 1 at drivers/gpu/drm/drm_gem_vram_helper.c:564 bo_driver_move_notify+0x8c/0x98
[ 27.798969] Modules linked in:
[ 27.802018] CPU: 24 PID: 1 Comm: swapper/0 Tainted: G B 5.5.0-rc1-dirty #565
[ 27.810358] Hardware name: Huawei D06 /D06, BIOS Hisilicon D06 UEFI RC0 - V1.16.01 03/15/2019
[ 27.818872] pstate: 20c00009 (nzCv daif +PAN +UAO)
[ 27.823654] pc : bo_driver_move_notify+0x8c/0x98
[ 27.828262] lr : bo_driver_move_notify+0x40/0x98
[ 27.832868] sp : ffff00236f0677e0
[ 27.836173] x29: ffff00236f0677e0 x28: ffffa0001454e5e0
[ 27.841476] x27: ffff002366e52128 x26: ffffa000149e67b0
[ 27.846779] x25: ffff002366e523e0 x24: ffff002336936120
[ 27.852082] x23: ffff0023346f4010 x22: ffff002336936128
[ 27.857385] x21: ffffa000149c15c0 x20: ffff0023369361f8
[ 27.862687] x19: ffff002336936000 x18: 0000000000001258
[ 27.867989] x17: 0000000000001190 x16: 00000000000011d0
[ 27.873292] x15: 0000000000001348 x14: ffffa00012d68190
[ 27.878595] x13: 0000000000000006 x12: 1ffff40003241f91
[ 27.883897] x11: ffff940003241f91 x10: dfffa00000000000
[ 27.889200] x9 : ffff940003241f92 x8 : 0000000000000001
[ 27.894502] x7 : ffffa0001920fc88 x6 : ffff940003241f92
[ 27.899804] x5 : ffff940003241f92 x4 : ffff0023369363a0
[ 27.905107] x3 : ffffa00010c104b8 x2 : dfffa00000000000
[ 27.910409] x1 : 0000000000000003 x0 : 0000000000000001
[ 27.915712] Call trace:
[ 27.918151] bo_driver_move_notify+0x8c/0x98
[ 27.922412] ttm_bo_cleanup_memtype_use+0x54/0x100
[ 27.927194] ttm_bo_put+0x3a0/0x5d0
[ 27.930673] drm_gem_vram_object_free+0xc/0x18
[ 27.935109] drm_gem_object_free+0x34/0xd0
[ 27.939196] drm_gem_object_put_unlocked+0xc8/0xf0
[ 27.943978] hibmc_user_framebuffer_destroy+0x20/0x40
[ 27.949020] drm_framebuffer_free+0x48/0x58
[ 27.953194] drm_mode_object_put.part.1+0x90/0xe8
[ 27.957889] drm_mode_object_put+0x28/0x38
[ 27.961976] hibmc_fbdev_fini+0x54/0x78
[ 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