Re: Warnings in DRM code when removing/unbinding a driver
Hi John Am 10.01.20 um 13:54 schrieb John Garry: > > > Hi Thomas, > >> drm-tip now contains > > I have tested today's linux-next, which includes this: > >> >> commit a88248506a2bcfeaef6837a53cde19fe11970e6c >> Author: Thomas Zimmermann >> 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: Great. So I'll consider this fixed. Thanks for reporting ad testing. Best regards Thomas > > [ 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 >>> :05:00.0 bind new_id remove_id uevent >>> unbind >>> root@(none)$ echo \: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: 2049 (nzCv daif +PAN -UAO) >>> [ 116.114001] pc : ttm_buffer_object_destroy+0x4c/0x80 >>> [ 116.118956] lr : ttm_buffer_object_destroy+0x18/0x80 >>> [ 116.123910]
Re: Warnings in DRM code when removing/unbinding a driver
Hi Thomas, drm-tip now contains I have tested today's linux-next, which includes this: commit a88248506a2bcfeaef6837a53cde19fe11970e6c Author: Thomas Zimmermann 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 :05:00.0 bind new_id remove_id uevent unbind root@(none)$ echo \: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: 2049 (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 : 0022e6cef8e0 [ 116.127215] x29: 0022e6cef8e0 x28: 00231b1fb000 [ 116.132519] x27: x26: 00231b1fb000 [ 116.137821] x25: 0022e6cefdc0 x24: 2480 [ 116.143124] x23: 0023682b6ab0 x22: 0023682b6800 [ 116.148427] x21: 0023682b6800 x20: [ 116.153730] x19: 0023682b6800 x18: [ 116.159032] x17: 001 [ 116.185545] x7 : 0023682b6b07 x6
Re: Warnings in DRM code when removing/unbinding a driver
Hi John Am 16.12.19 um 18:23 schrieb John Garry: > 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: 20c9 (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 : 00236f0677e0 > [ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0 > [ 27.841476] x27: 002366e52128 x26: a000149e67b0 > [ 27.846779] x25: 002366e523e0 x24: 002336936120 > [ 27.852082] x23: 0023346f4010 x22: 002336936128 > [ 27.857385] x21: a000149c15c0 x20: 0023369361f8 > [ 27.862687] x19: 002336936000 x18: 1258 > [ 27.867989] x17: 1190 x16: 11d0 > [ 27.873292] x15: 1348 x14: a00012d68190 > [ 27.878595] x13: 0006 x12: 140003241f91 > [ 27.883897] x11: 940003241f91 x10: dfffa000 > [ 27.889200] x9 : 940003241f92 x8 : 0001 > [ 27.894502] x7 : a0001920fc88 x6 : 940003241f92 > [ 27.899804] x5 : 940003241f92 x4 : 0023369363a0 > [ 27.905107] x3 : a00010c104b8 x2 : dfffa000 > [ 27.910409] x1 : 0003 x0 : 0001 > [ 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 drm-tip now contains commit a88248506a2bcfeaef6837a53cde19fe11970e6c Author: Thomas Zimmermann 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? 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 > :05:00.0 bind new_id remove_id uevent > unbind > root@(none)$ echo \: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: 2049 (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 : 0022e6cef8e0 > [ 116.127215] x29: 0022e6cef8e0 x28: 00231b1fb000 > [ 116.132519] x27: x26: 00231b1fb000 > [ 116.137821] x25: 0022e6cefdc0 x24: 2480 > [ 116.143124] x23: 0023682b6ab0 x22: 0023682b6800 > [ 116.148427] x21: 0023682b6800 x20: > [
Re: SIGBUS on device disappearance (Re: Warnings in DRM code when removing/unbinding a driver)
On Mon, Dec 23, 2019 at 11:00:15AM +0200, Pekka Paalanen wrote: > On Thu, 19 Dec 2019 13:42:33 +0100 > Daniel Vetter wrote: > > > On Thu, Dec 19, 2019 at 12:32 PM Gerd Hoffmann wrote: > > > > > > While being at it: How would a driver cleanup properly cleanup gem > > > objects created by userspace on hotunbind? Specifically a gem object > > > pinned to vram? > > > > Two things: > > - the mmap needs to be torn down and replaced by something which will > > sigbus. Probably should have that as a helper (plus vram fault code > > should use drm_dev_enter/exit to plug races). > > Hi, > > I assume SIGBUS is the traditional way to say "oops, the memory you > mmapped and tried to access no longer exists". Is there nothing > else for this? > > I'm asking, because SIGBUS is really hard to handle right in > userspace. It can be caused by any number of wildly different > reasons, yet being a signal means that a userspace process can only > have a single global handler for it. That makes it almost > impossible to use safely in libraries, because you would want to > register independent handlers from multiple libraries in the same > process. Some libraries may also be using threads. > > How to handle a SIGBUS completely depends on what triggered it. > Almost always userspace wants it to be a non-fatal error. A Wayland > compositor can hit SIGBUS on accessing wl_shm-based client buffers > (regular mmapped files), and then it just wants to continue with > garbage data as if nothing happened and possibly send a protocol > error to the client provoking it. For drm drivers that you actually want to hotunplug (as opposed to more just for driver development) they all use system memory/shmem, so shouldn't sigbus. I think at least, I haven't tested anything. This is for udl, or the tiny displays behind an spi bridge. For pci drivers where the mmap often points at a pci bridge the mmio range will be gone, so not SIGBUSing is going to be a tough order. Not impossible, but before we enshrine this into uapi someont will have to do some serious typing. > I would also imagine that Mesa, when it starts looking into > supporting GPU hotunplug, needs to handle vanished mmaps. I don't > think Mesa can ever install signal handlers, because that would > mess with the applications that may already be using SIGBUS for > handling disappearing mmapped files. It needs to start returning > errors via API calls. I cannot imagine a way to reliably prevent > such SIGBUS either by e.g. ensuring Mesa gets notified of removal > before it actually starts failing. Mesa already blows up in all kinds of interesting ways when it gets an EIO at execbuf. I think. Robust handling of gpu hotunplug for gl/vk contexts is going to be more work on top (and mmap is probably the least issue there, at least right now). > For now, I'm just looking for a simple "yes" or "no" here for the > something else. If it's "no" like I expect, creating something else > is probably in the order of years to get into a usable state. Does > anyone already have plans towards that? I agree with you that SIGBUS for mmap of hotunplugged devices is essentially unusable because sighandlers and all what you point out (would make it impossible to have robust vk/gl contexts, at least robuts against hotunplug). So in principle I'm open to have some other uapi for this, but it's going to be serios amounts of work across the stack. For display only udl-style devices otoh I think we should be mostly there, +/- driver bugs as usual. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
SIGBUS on device disappearance (Re: Warnings in DRM code when removing/unbinding a driver)
On Thu, 19 Dec 2019 13:42:33 +0100 Daniel Vetter wrote: > On Thu, Dec 19, 2019 at 12:32 PM Gerd Hoffmann wrote: > > > > While being at it: How would a driver cleanup properly cleanup gem > > objects created by userspace on hotunbind? Specifically a gem object > > pinned to vram? > > Two things: > - the mmap needs to be torn down and replaced by something which will > sigbus. Probably should have that as a helper (plus vram fault code > should use drm_dev_enter/exit to plug races). Hi, I assume SIGBUS is the traditional way to say "oops, the memory you mmapped and tried to access no longer exists". Is there nothing else for this? I'm asking, because SIGBUS is really hard to handle right in userspace. It can be caused by any number of wildly different reasons, yet being a signal means that a userspace process can only have a single global handler for it. That makes it almost impossible to use safely in libraries, because you would want to register independent handlers from multiple libraries in the same process. Some libraries may also be using threads. How to handle a SIGBUS completely depends on what triggered it. Almost always userspace wants it to be a non-fatal error. A Wayland compositor can hit SIGBUS on accessing wl_shm-based client buffers (regular mmapped files), and then it just wants to continue with garbage data as if nothing happened and possibly send a protocol error to the client provoking it. I would also imagine that Mesa, when it starts looking into supporting GPU hotunplug, needs to handle vanished mmaps. I don't think Mesa can ever install signal handlers, because that would mess with the applications that may already be using SIGBUS for handling disappearing mmapped files. It needs to start returning errors via API calls. I cannot imagine a way to reliably prevent such SIGBUS either by e.g. ensuring Mesa gets notified of removal before it actually starts failing. For now, I'm just looking for a simple "yes" or "no" here for the something else. If it's "no" like I expect, creating something else is probably in the order of years to get into a usable state. Does anyone already have plans towards that? Thanks, pq pgpnyCIKvyxtw.pgp Description: OpenPGP digital signature ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Warnings in DRM code when removing/unbinding a driver
On 19/12/2019 09:54, Daniel Vetter wrote: On Wed, Dec 18, 2019 at 7:08 PM John Garry wrote: + So the v5.4 kernel does not have this issue. I have bisected the initial occurrence to: commit 37a48adfba6cf6e87df9ba8b75ab85d514ed86d8 Author: Thomas Zimmermann Date: Fri Sep 6 14:20:53 2019 +0200 drm/vram: Add kmap ref-counting to GEM VRAM objects The kmap and kunmap operations of GEM VRAM buffers can now be called in interleaving pairs. The first call to drm_gem_vram_kmap() maps the buffer's memory to kernel address space and the final call to drm_gem_vram_kunmap() unmaps the memory. Intermediate calls to these functions increment or decrement a reference counter. So this either exposes or creates the issue. Yeah that's just shooting the messenger. OK, so it exposes it. Like I said, for most drivers you can pretty much assume that their unload sequence has been broken since forever. It's not often tested, and especially the hotunbind from a device (as opposed to driver unload) stuff wasn't even possible to get right until just recently. Do you think it's worth trying to fix this for 5.5 and earlier, or just switch to the device-managed interface for 5.6 and forget about 5.5 and earlier? Thanks, John ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Warnings in DRM code when removing/unbinding a driver
On Thu, Dec 19, 2019 at 12:32 PM Gerd Hoffmann wrote: > > Hi, > > > > Like I said, for most drivers > > > > you can pretty much assume that their unload sequence has been broken > > > > since forever. It's not often tested, and especially the hotunbind > > > > from a device (as opposed to driver unload) stuff wasn't even possible > > > > to get right until just recently. > > > > > > Do you think it's worth trying to fix this for 5.5 and earlier, or just > > > switch to the device-managed interface for 5.6 and forget about 5.5 and > > > earlier? > > > > I suspect it's going to be quite some trickery to fix this properly > > and everywhere, even for just one driver. Lots of drm drivers > > unfortunately use anti-patterns with wrong lifetimes (e.g. you can't > > use devm_kmalloc for anything that hangs of a drm_device, like > > plane/crtc/connector). Except when it's for a real hotunpluggable > > device (usb) we've never bothered backporting these fixes. Too much > > broken stuff unfortunately. > > While being at it: How would a driver cleanup properly cleanup gem > objects created by userspace on hotunbind? Specifically a gem object > pinned to vram? Two things: - the mmap needs to be torn down and replaced by something which will sigbus. Probably should have that as a helper (plus vram fault code should use drm_dev_enter/exit to plug races). - otherwise all datastructures need to be properly refcounted. drm_device now is (if your driver isn't broken), but any dma_fence or dma_buf we create and export has an independent lifetime, and currently the refcounting for is still wobbly I think. So some work to do, both in helpers/core code and in drivers to get updated. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Warnings in DRM code when removing/unbinding a driver
Hi, > > Like I said, for most drivers > > > you can pretty much assume that their unload sequence has been broken > > > since forever. It's not often tested, and especially the hotunbind > > > from a device (as opposed to driver unload) stuff wasn't even possible > > > to get right until just recently. > > > > Do you think it's worth trying to fix this for 5.5 and earlier, or just > > switch to the device-managed interface for 5.6 and forget about 5.5 and > > earlier? > > I suspect it's going to be quite some trickery to fix this properly > and everywhere, even for just one driver. Lots of drm drivers > unfortunately use anti-patterns with wrong lifetimes (e.g. you can't > use devm_kmalloc for anything that hangs of a drm_device, like > plane/crtc/connector). Except when it's for a real hotunpluggable > device (usb) we've never bothered backporting these fixes. Too much > broken stuff unfortunately. While being at it: How would a driver cleanup properly cleanup gem objects created by userspace on hotunbind? Specifically a gem object pinned to vram? cheers, Gerd ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Warnings in DRM code when removing/unbinding a driver
On Thu, Dec 19, 2019 at 11:03 AM John Garry wrote: > > On 19/12/2019 09:54, Daniel Vetter wrote: > > On Wed, Dec 18, 2019 at 7:08 PM John Garry wrote: > >> > >> + > >> > >> So the v5.4 kernel does not have this issue. > >> > >> I have bisected the initial occurrence to: > >> > >> commit 37a48adfba6cf6e87df9ba8b75ab85d514ed86d8 > >> Author: Thomas Zimmermann > >> Date: Fri Sep 6 14:20:53 2019 +0200 > >> > >> drm/vram: Add kmap ref-counting to GEM VRAM objects > >> > >> The kmap and kunmap operations of GEM VRAM buffers can now be called > >> in interleaving pairs. The first call to drm_gem_vram_kmap() maps the > >> buffer's memory to kernel address space and the final call to > >> drm_gem_vram_kunmap() unmaps the memory. Intermediate calls to these > >> functions increment or decrement a reference counter. > >> > >> So this either exposes or creates the issue. > > > > Yeah that's just shooting the messenger. > > OK, so it exposes it. > > Like I said, for most drivers > > you can pretty much assume that their unload sequence has been broken > > since forever. It's not often tested, and especially the hotunbind > > from a device (as opposed to driver unload) stuff wasn't even possible > > to get right until just recently. > > Do you think it's worth trying to fix this for 5.5 and earlier, or just > switch to the device-managed interface for 5.6 and forget about 5.5 and > earlier? I suspect it's going to be quite some trickery to fix this properly and everywhere, even for just one driver. Lots of drm drivers unfortunately use anti-patterns with wrong lifetimes (e.g. you can't use devm_kmalloc for anything that hangs of a drm_device, like plane/crtc/connector). Except when it's for a real hotunpluggable device (usb) we've never bothered backporting these fixes. Too much broken stuff unfortunately. -Daniel > > Thanks, > John -- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57 48 - http://blog.ffwll.ch ___ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
Re: Warnings in DRM code when removing/unbinding a driver
On Wed, Dec 18, 2019 at 7:08 PM John Garry wrote:
>
> +
>
> So the v5.4 kernel does not have this issue.
>
> I have bisected the initial occurrence to:
>
> commit 37a48adfba6cf6e87df9ba8b75ab85d514ed86d8
> Author: Thomas Zimmermann
> Date: Fri Sep 6 14:20:53 2019 +0200
>
> drm/vram: Add kmap ref-counting to GEM VRAM objects
>
> The kmap and kunmap operations of GEM VRAM buffers can now be called
> in interleaving pairs. The first call to drm_gem_vram_kmap() maps the
> buffer's memory to kernel address space and the final call to
> drm_gem_vram_kunmap() unmaps the memory. Intermediate calls to these
> functions increment or decrement a reference counter.
>
> So this either exposes or creates the issue.
Yeah that's just shooting the messenger. Like I said, for most drivers
you can pretty much assume that their unload sequence has been broken
since forever. It's not often tested, and especially the hotunbind
from a device (as opposed to driver unload) stuff wasn't even possible
to get right until just recently.
-Daniel
>
> John
>
> >> On Mon, 2019-12-16 at 17:23 +, John Garry wrote:
> >>> 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
> >>
> >> A total shot in the dark. This might make no sense,
> >> but it's worth a try:
> >
> > Thanks for the suggestion, but still the same splat.
> >
> > I haven't had a chance to analyze the problem myself. But perhaps we
> > should just change over the device-managed interface, as Daniel mentioned.
> >
> >>
> >> diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> >> b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> >> index 2fd4ca91a62d..69bb0e29da88 100644
> >> --- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> >> +++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
> >> @@ -247,9 +247,8 @@ static int hibmc_unload(struct drm_device *dev)
> >> {
> >> struct hibmc_drm_private *priv = dev->dev_private;
> >> - hibmc_fbdev_fini(priv);
> >> -
> >> drm_atomic_helper_shutdown(dev);
> >> + hibmc_fbdev_fini(priv);
> >> if (dev->irq_enabled)
> >> drm_irq_uninstall(dev);
> >>
> >> Hope it helps,
> >> Ezequiel
> >>
> >
> > Thanks,
> > John
> >
> > [EOM]
> >
> >>> [ 27.798969] Modules linked in:
> >>> [ 27.802018] CPU: 24 PID: 1 Comm: swapper/0 Tainted: GB
> >>>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: 20c9 (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 : 00236f0677e0
> >>> [ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0
> >>> [ 27.841476] x27: 002366e52128 x26: a000149e67b0
> >>> [ 27.846779] x25: 002366e523e0 x24: 002336936120
> >>> [ 27.852082] x23: 0023346f4010 x22: 002336936128
> >>> [ 27.857385] x21: a000149c15c0 x20: 0023369361f8
> >>> [ 27.862687] x19: 002336936000 x18: 1258
> >>> [ 27.867989] x17: 1190 x16: 11d0
> >>> [ 27.873292] x15: 1348 x14: a00012d68190
> >>> [ 27.878595] x13: 0006 x12: 140003241f91
> >>> [ 27.883897] x11: 940003241f91 x10: dfffa000
> >>> [ 27.889200] x9 : 940003241f92 x8 : 0001
> >>> [ 27.894502] x7 : a0001920fc88 x6 : 940003241f92
> >>> [ 27.899804] x5 : 940003241f92 x4 : 0023369363a0
> >>> [ 27.905107] x3 : a00010c104b8 x2 : dfffa000
> >>> [ 27.910409] x1 : 0003 x0 : 0001
> >>> [ 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]
Re: Warnings in DRM code when removing/unbinding a driver
+
So the v5.4 kernel does not have this issue.
I have bisected the initial occurrence to:
commit 37a48adfba6cf6e87df9ba8b75ab85d514ed86d8
Author: Thomas Zimmermann
Date: Fri Sep 6 14:20:53 2019 +0200
drm/vram: Add kmap ref-counting to GEM VRAM objects
The kmap and kunmap operations of GEM VRAM buffers can now be called
in interleaving pairs. The first call to drm_gem_vram_kmap() maps the
buffer's memory to kernel address space and the final call to
drm_gem_vram_kunmap() unmaps the memory. Intermediate calls to these
functions increment or decrement a reference counter.
So this either exposes or creates the issue.
John
On Mon, 2019-12-16 at 17:23 +, John Garry wrote:
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
A total shot in the dark. This might make no sense,
but it's worth a try:
Thanks for the suggestion, but still the same splat.
I haven't had a chance to analyze the problem myself. But perhaps we
should just change over the device-managed interface, as Daniel mentioned.
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index 2fd4ca91a62d..69bb0e29da88 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -247,9 +247,8 @@ static int hibmc_unload(struct drm_device *dev)
{
struct hibmc_drm_private *priv = dev->dev_private;
- hibmc_fbdev_fini(priv);
-
drm_atomic_helper_shutdown(dev);
+ hibmc_fbdev_fini(priv);
if (dev->irq_enabled)
drm_irq_uninstall(dev);
Hope it helps,
Ezequiel
Thanks,
John
[EOM]
[ 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: 20c9 (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 : 00236f0677e0
[ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0
[ 27.841476] x27: 002366e52128 x26: a000149e67b0
[ 27.846779] x25: 002366e523e0 x24: 002336936120
[ 27.852082] x23: 0023346f4010 x22: 002336936128
[ 27.857385] x21: a000149c15c0 x20: 0023369361f8
[ 27.862687] x19: 002336936000 x18: 1258
[ 27.867989] x17: 1190 x16: 11d0
[ 27.873292] x15: 1348 x14: a00012d68190
[ 27.878595] x13: 0006 x12: 140003241f91
[ 27.883897] x11: 940003241f91 x10: dfffa000
[ 27.889200] x9 : 940003241f92 x8 : 0001
[ 27.894502] x7 : a0001920fc88 x6 : 940003241f92
[ 27.899804] x5 : 940003241f92 x4 : 0023369363a0
[ 27.905107] x3 : a00010c104b8 x2 : dfffa000
[ 27.910409] x1 : 0003 x0 : 0001
[ 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
Re: Warnings in DRM code when removing/unbinding a driver
Hi Ezequiel,
On Mon, 2019-12-16 at 17:23 +, John Garry wrote:
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
A total shot in the dark. This might make no sense,
but it's worth a try:
Thanks for the suggestion, but still the same splat.
I haven't had a chance to analyze the problem myself. But perhaps we
should just change over the device-managed interface, as Daniel mentioned.
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index 2fd4ca91a62d..69bb0e29da88 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -247,9 +247,8 @@ static int hibmc_unload(struct drm_device *dev)
{
struct hibmc_drm_private *priv = dev->dev_private;
- hibmc_fbdev_fini(priv);
-
drm_atomic_helper_shutdown(dev);
+ hibmc_fbdev_fini(priv);
if (dev->irq_enabled)
drm_irq_uninstall(dev);
Hope it helps,
Ezequiel
Thanks,
John
[EOM]
[ 27.798969] Modules linked in:
[ 27.802018] CPU: 24 PID: 1 Comm: swapper/0 Tainted: GB
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: 20c9 (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 : 00236f0677e0
[ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0
[ 27.841476] x27: 002366e52128 x26: a000149e67b0
[ 27.846779] x25: 002366e523e0 x24: 002336936120
[ 27.852082] x23: 0023346f4010 x22: 002336936128
[ 27.857385] x21: a000149c15c0 x20: 0023369361f8
[ 27.862687] x19: 002336936000 x18: 1258
[ 27.867989] x17: 1190 x16: 11d0
[ 27.873292] x15: 1348 x14: a00012d68190
[ 27.878595] x13: 0006 x12: 140003241f91
[ 27.883897] x11: 940003241f91 x10: dfffa000
[ 27.889200] x9 : 940003241f92 x8 : 0001
[ 27.894502] x7 : a0001920fc88 x6 : 940003241f92
[ 27.899804] x5 : 940003241f92 x4 : 0023369363a0
[ 27.905107] x3 : a00010c104b8 x2 : dfffa000
[ 27.910409] x1 : 0003 x0 : 0001
[ 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: GB 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
:05:00.0 bind new_idremove_id ueventunbind
root@(none)$ echo \: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: GB 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: 2049 (nzCv daif +PAN -UAO)
[ 116.114001] pc :
Re: Warnings in DRM code when removing/unbinding a driver
On 16/12/2019 17:23, John Garry wrote: +, - Hi all, xinliang is bouncing. We need to get his new mail address. John 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: 20c9 (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 : 00236f0677e0 [ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0 [ 27.841476] x27: 002366e52128 x26: a000149e67b0 [ 27.846779] x25: 002366e523e0 x24: 002336936120 [ 27.852082] x23: 0023346f4010 x22: 002336936128 [ 27.857385] x21: a000149c15c0 x20: 0023369361f8 [ 27.862687] x19: 002336936000 x18: 1258 [ 27.867989] x17: 1190 x16: 11d0 [ 27.873292] x15: 1348 x14: a00012d68190 [ 27.878595] x13: 0006 x12: 140003241f91 [ 27.883897] x11: 940003241f91 x10: dfffa000 [ 27.889200] x9 : 940003241f92 x8 : 0001 [ 27.894502] x7 : a0001920fc88 x6 : 940003241f92 [ 27.899804] x5 : 940003241f92 x4 : 0023369363a0 [ 27.905107] x3 : a00010c104b8 x2 : dfffa000 [ 27.910409] x1 : 0003 x0 : 0001 [ 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 :05:00.0 bind new_id remove_id uevent unbind root@(none)$ echo \: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: 2049 (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 : 0022e6cef8e0 [ 116.127215] x29: 0022e6cef8e0 x28: 00231b1fb000 [ 116.132519] x27: x26: 00231b1fb000 [ 116.137821] x25: 0022e6cefdc0 x24: 2480 [ 116.143124] x23: 0023682b6ab0 x22: 0023682b6800 [ 116.148427] x21: 0023682b6800 x20: [ 116.153730] x19: 0023682b6800 x18: [ 116.159032] x17: 001 [ 116.185545] x7 : 0023682b6b07 x6 : 80046d056d61 [ 116.190848] x5 : 80046d056d61 x4 : 0023682b6ba0 [ 116.196151] x3 : a00010197338 x2 : dfffa000 [ 116.201453] x1 : 0003 x0 : 0001 [ 116.206756] Call trace: [ 116.209195] ttm_buffer_object_destroy+0x4c/0x80 [
Re: Warnings in DRM code when removing/unbinding a driver
Hi John,
On Mon, 2019-12-16 at 17:23 +, John Garry wrote:
> 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
A total shot in the dark. This might make no sense,
but it's worth a try:
diff --git a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
index 2fd4ca91a62d..69bb0e29da88 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
+++ b/drivers/gpu/drm/hisilicon/hibmc/hibmc_drm_drv.c
@@ -247,9 +247,8 @@ static int hibmc_unload(struct drm_device *dev)
{
struct hibmc_drm_private *priv = dev->dev_private;
- hibmc_fbdev_fini(priv);
-
drm_atomic_helper_shutdown(dev);
+ hibmc_fbdev_fini(priv);
if (dev->irq_enabled)
drm_irq_uninstall(dev);
Hope it helps,
Ezequiel
> [ 27.798969] Modules linked in:
> [ 27.802018] CPU: 24 PID: 1 Comm: swapper/0 Tainted: GB
> 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: 20c9 (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 : 00236f0677e0
> [ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0
> [ 27.841476] x27: 002366e52128 x26: a000149e67b0
> [ 27.846779] x25: 002366e523e0 x24: 002336936120
> [ 27.852082] x23: 0023346f4010 x22: 002336936128
> [ 27.857385] x21: a000149c15c0 x20: 0023369361f8
> [ 27.862687] x19: 002336936000 x18: 1258
> [ 27.867989] x17: 1190 x16: 11d0
> [ 27.873292] x15: 1348 x14: a00012d68190
> [ 27.878595] x13: 0006 x12: 140003241f91
> [ 27.883897] x11: 940003241f91 x10: dfffa000
> [ 27.889200] x9 : 940003241f92 x8 : 0001
> [ 27.894502] x7 : a0001920fc88 x6 : 940003241f92
> [ 27.899804] x5 : 940003241f92 x4 : 0023369363a0
> [ 27.905107] x3 : a00010c104b8 x2 : dfffa000
> [ 27.910409] x1 : 0003 x0 : 0001
> [ 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: GB 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
> :05:00.0 bind new_idremove_id ueventunbind
> root@(none)$ echo \: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: GB 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: 2049 (nzCv daif +PAN -UAO)
> [ 116.114001] pc : ttm_buffer_object_destroy+0x4c/0x80
> [ 116.118956] lr :
Re: Warnings in DRM code when removing/unbinding a driver
On Tue, Dec 17, 2019 at 09:20:43AM +, John Garry wrote: > On 16/12/2019 17:23, John Garry wrote: > > +, - > > > Hi all, > > xinliang is bouncing. We need to get his new > mail address. > > John > > > > > 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: 20c9 (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 : 00236f0677e0 > > [ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0 > > [ 27.841476] x27: 002366e52128 x26: a000149e67b0 > > [ 27.846779] x25: 002366e523e0 x24: 002336936120 > > [ 27.852082] x23: 0023346f4010 x22: 002336936128 > > [ 27.857385] x21: a000149c15c0 x20: 0023369361f8 > > [ 27.862687] x19: 002336936000 x18: 1258 > > [ 27.867989] x17: 1190 x16: 11d0 > > [ 27.873292] x15: 1348 x14: a00012d68190 > > [ 27.878595] x13: 0006 x12: 140003241f91 > > [ 27.883897] x11: 940003241f91 x10: dfffa000 > > [ 27.889200] x9 : 940003241f92 x8 : 0001 > > [ 27.894502] x7 : a0001920fc88 x6 : 940003241f92 > > [ 27.899804] x5 : 940003241f92 x4 : 0023369363a0 > > [ 27.905107] x3 : a00010c104b8 x2 : dfffa000 > > [ 27.910409] x1 : 0003 x0 : 0001 > > [ 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 > > :05:00.0 bind new_id remove_id uevent > > unbind > > root@(none)$ echo \: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: 2049 (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 : 0022e6cef8e0 > > [ 116.127215] x29: 0022e6cef8e0 x28: 00231b1fb000 > > [ 116.132519] x27: x26: 00231b1fb000 > > [ 116.137821] x25: 0022e6cefdc0 x24: 2480 > > [ 116.143124] x23: 0023682b6ab0 x22: 0023682b6800 > > [ 116.148427] x21: 0023682b6800 x20:
Warnings in DRM code when removing/unbinding a driver
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: GB 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: 20c9 (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 : 00236f0677e0 [ 27.836173] x29: 00236f0677e0 x28: a0001454e5e0 [ 27.841476] x27: 002366e52128 x26: a000149e67b0 [ 27.846779] x25: 002366e523e0 x24: 002336936120 [ 27.852082] x23: 0023346f4010 x22: 002336936128 [ 27.857385] x21: a000149c15c0 x20: 0023369361f8 [ 27.862687] x19: 002336936000 x18: 1258 [ 27.867989] x17: 1190 x16: 11d0 [ 27.873292] x15: 1348 x14: a00012d68190 [ 27.878595] x13: 0006 x12: 140003241f91 [ 27.883897] x11: 940003241f91 x10: dfffa000 [ 27.889200] x9 : 940003241f92 x8 : 0001 [ 27.894502] x7 : a0001920fc88 x6 : 940003241f92 [ 27.899804] x5 : 940003241f92 x4 : 0023369363a0 [ 27.905107] x3 : a00010c104b8 x2 : dfffa000 [ 27.910409] x1 : 0003 x0 : 0001 [ 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: GB 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 :05:00.0 bind new_idremove_id ueventunbind root@(none)$ echo \: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: GB 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: 2049 (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 : 0022e6cef8e0 [ 116.127215] x29: 0022e6cef8e0 x28: 00231b1fb000 [ 116.132519] x27: x26: 00231b1fb000 [ 116.137821] x25: 0022e6cefdc0 x24: 2480 [ 116.143124] x23: 0023682b6ab0 x22: 0023682b6800 [ 116.148427] x21: 0023682b6800 x20: [ 116.153730] x19: 0023682b6800 x18: [ 116.159032] x17: 001 [ 116.185545] x7 : 0023682b6b07 x6 : 80046d056d61 [ 116.190848] x5 : 80046d056d61 x4 : 0023682b6ba0 [ 116.196151] x3 : a00010197338 x2 : dfffa000 [ 116.201453] x1 : 0003 x0 : 0001 [ 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 [
