[Ksummit-discuss] [TECH TOPIC] Addressing complex dependencies and semantics (v2)
Rob Herring
robherring2 at gmail.com
Fri Aug 5 19:27:33 UTC 2016
On Fri, Aug 5, 2016 at 5:54 AM, Greg KH <greg at kroah.com> wrote:
> On Fri, Aug 05, 2016 at 11:01:43AM +0200, Arnd Bergmann wrote:
>> On Thursday, August 4, 2016 9:59:30 PM CEST Rob Herring wrote:
>> > On Thu, Aug 4, 2016 at 5:20 AM, Mark Brown <broonie at kernel.org> wrote:
>> > > On Thu, Aug 04, 2016 at 11:50:49AM +0200, Greg KH wrote:
>> > >
>> > >> Nope, it doesn't work that way, sorry.
>> > >
>> > >> Nice try, just unwind your initialization properly
>> > >
>> > > Deferred probe is probably the best thing that ever happened for the
>> > > quality of kernel error handling
>> >
>> > Now we just need a way to force testing of the remove functions.
>>
>> Hmm, instead of calling just 'probe', we might first call probe,
>> then remove, then probe again as a compile-time option.
>>
>> What could possibly go wrong? ;-)
>
> Ooooh, that would be fun to see what blows up, anyone want to try it?
Well, I couldn't resist. Here's results from an x86 VM image.
There's some interesting side effects like this:
[ 1.088470] input: QEMU Virtio Mouse as
/devices/pci0000:00/0000:00:07.0/virtio5/input/input2
[ 1.089813] input: QEMU Virtio Mouse as
/devices/pci0000:00/0000:00:07.0/virtio5/input/input3
[ 1.090945] input: QEMU Virtio Keyboard as
/devices/pci0000:00/0000:00:08.0/virtio6/input/input4
[ 1.092275] input: QEMU Virtio Keyboard as
/devices/pci0000:00/0000:00:08.0/virtio6/input/input5
Then it blows up on the DRM driver which is virtio-gpu in this case.
[ 1.277522] [drm] Initialized drm 1.1.0 20060810
[ 1.277926] [drm] pci: virtio-gpu-pci detected
[ 1.278389] [drm] virgl 3d acceleration enabled
[ 1.278992] [drm] virtio vbuffers: 272 bufs, 192B each, 51kB total.
[ 1.279487] [TTM] Zone kernel: Available graphics memory: 506732 kiB
[ 1.279931] [TTM] Initializing pool allocator
[ 1.280247] [TTM] Initializing DMA pool allocator
[ 1.280581] [drm] number of scanouts: 1
[ 1.280847] [drm] number of cap sets: 1
[ 1.281257] [drm] cap set 0: id 1, max-version 1, max-size 308
[ 1.282451] virtio_gpu virtio4: fb0: virtiodrmfb frame buffer device
[ 1.287125] [drm] Initialized virtio_gpu 0.0.1 0 on minor 0
[ 1.291198] ------------[ cut here ]------------
[ 1.291654] WARNING: CPU: 0 PID: 1 at
../drivers/gpu/drm/drm_mm.c:773 drm_mm_takedown+0x2a/0x30
[ 1.292407] Memory manager not clean during takedown.
[ 1.292752] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W
4.7.0-rc7+ #17
[ 1.293257] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
[ 1.294047] 0000000000000000 ffff88003e247bc8 ffffffff8133a383
ffff88003e247c18
[ 1.294579] 0000000000000000 ffff88003e247c08 ffffffff81056ca1
000003053e247c20
[ 1.295110] ffff88003da904d8 ffff88003da90078 0000000000000000
ffff88003d6b9740
[ 1.295648] Call Trace:
[ 1.295821] [<ffffffff8133a383>] dump_stack+0x65/0x92
[ 1.296169] [<ffffffff81056ca1>] __warn+0xc1/0xe0
[ 1.296494] [<ffffffff81056d0a>] warn_slowpath_fmt+0x4a/0x50
[ 1.296883] [<ffffffff819560a9>] ? _raw_spin_unlock+0x9/0x10
[ 1.297271] [<ffffffff8133bed6>] ? ida_destroy+0x16/0x20
[ 1.297637] [<ffffffff8142ccaa>] drm_mm_takedown+0x2a/0x30
[ 1.298016] [<ffffffff8143d656>] drm_vma_offset_manager_destroy+0x16/0x30
[ 1.298480] [<ffffffff814475c6>] ttm_bo_device_release+0xf6/0x120
[ 1.298898] [<ffffffff815142b1>] virtio_gpu_ttm_fini+0x11/0x40
[ 1.299298] [<ffffffff81510700>] virtio_gpu_driver_unload+0x60/0xc0
[ 1.299736] [<ffffffff81429564>] drm_dev_unregister+0x24/0xa0
[ 1.300132] [<ffffffff814295fe>] drm_put_dev+0x1e/0x60
[ 1.300487] [<ffffffff8150fff0>] virtio_gpu_remove+0x10/0x20
[ 1.300876] [<ffffffff813ce1cb>] virtio_dev_remove+0x3b/0xa0
[ 1.301265] [<ffffffff8151dbc4>] driver_probe_device+0xf4/0x3b0
[ 1.301671] [<ffffffff8151df16>] __driver_attach+0x96/0xa0
[ 1.302048] [<ffffffff8151de80>] ? driver_probe_device+0x3b0/0x3b0
[ 1.302471] [<ffffffff8151be0f>] bus_for_each_dev+0x5f/0x90
[ 1.302855] [<ffffffff8151dff9>] driver_attach+0x19/0x20
[ 1.303221] [<ffffffff8151c8e0>] bus_add_driver+0x1a0/0x210
[ 1.303618] [<ffffffff81f8d605>] ?
trace_event_define_fields_switch_mm+0xb3/0xb3
[ 1.304121] [<ffffffff8151e83b>] driver_register+0x5b/0xd0
[ 1.304499] [<ffffffff81f8d605>] ?
trace_event_define_fields_switch_mm+0xb3/0xb3
[ 1.305003] [<ffffffff813ce6fb>] register_virtio_driver+0x1b/0x30
[ 1.305421] [<ffffffff81f8d615>] virtio_gpu_driver_init+0x10/0x12
[ 1.305841] [<ffffffff81f49007>] do_one_initcall+0x8a/0x11a
[ 1.306225] [<ffffffff81f491f8>] kernel_init_freeable+0x161/0x1ec
[ 1.306643] [<ffffffff81950319>] kernel_init+0x9/0x100
[ 1.306997] [<ffffffff8195647f>] ret_from_fork+0x1f/0x40
[ 1.307364] [<ffffffff81950310>] ? rest_init+0x90/0x90
[ 1.307736] ---[ end trace 143836688e11e498 ]---
[ 1.308060] [TTM] Finalizing pool allocator
[ 1.308364] [TTM] Finalizing DMA pool allocator
[ 1.308826] [TTM] Zone kernel: Used memory at exit: 5153 kiB
[ 1.309274] [drm] virtio_gpu: ttm finalized
[ 1.309576] ------------[ cut here ]------------
[ 1.309893] kernel BUG at ../mm/slub.c:3657!
[ 1.310187] invalid opcode: 0000 [#1] PREEMPT SMP
[ 1.310507] CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W
4.7.0-rc7+ #17
[ 1.311014] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996),
BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
[ 1.311873] task: ffff88003e258000 ti: ffff88003e244000 task.ti:
ffff88003e244000
[ 1.312451] RIP: 0010:[<ffffffff81172c54>] [<ffffffff81172c54>]
kfree+0x144/0x180
[ 1.313023] RSP: 0000:ffff88003e247cc8 EFLAGS: 00010246
[ 1.313424] RAX: ffff88003ffd67e0 RBX: ffff88003da90000 RCX: 000000000002b840
[ 1.313956] RDX: 0000000000000000 RSI: ffff88003fa176c0 RDI: ffff88003ffd67df
[ 1.314482] RBP: ffff88003e247ce0 R08: 00000000000176c0 R09: ffffffff81510744
[ 1.315008] R10: ffffea0000f6a400 R11: 0000000000000600 R12: ffff88003da99250
[ 1.315542] R13: ffffffff8151074c R14: ffff88003da99250 R15: ffff88003fa16340
[ 1.316080] FS: 0000000000000000(0000) GS:ffff88003fa00000(0000)
knlGS:0000000000000000
[ 1.316680] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1.317108] CR2: 0000000000000000 CR3: 0000000001e07000 CR4: 00000000000006f0
[ 1.317674] Stack:
[ 1.317828] ffff88003da99250 ffff88003da99250 ffff88003da90000
ffff88003e247d10
[ 1.318407] ffffffff8151074c ffff88003d479800 ffff88003d479800
ffff88003e379408
[ 1.318997] ffffffff81ea2480 ffff88003e247d38 ffffffff81429564
ffff88003d479800
[ 1.319564] Call Trace:
[ 1.319749] [<ffffffff8151074c>] virtio_gpu_driver_unload+0xac/0xc0
[ 1.320221] [<ffffffff81429564>] drm_dev_unregister+0x24/0xa0
[ 1.320650] [<ffffffff814295fe>] drm_put_dev+0x1e/0x60
[ 1.321069] [<ffffffff8150fff0>] virtio_gpu_remove+0x10/0x20
[ 1.321628] [<ffffffff813ce1cb>] virtio_dev_remove+0x3b/0xa0
[ 1.322236] [<ffffffff8151dbc4>] driver_probe_device+0xf4/0x3b0
[ 1.322879] [<ffffffff8151df16>] __driver_attach+0x96/0xa0
[ 1.323425] [<ffffffff8151de80>] ? driver_probe_device+0x3b0/0x3b0
[ 1.323969] [<ffffffff8151be0f>] bus_for_each_dev+0x5f/0x90
[ 1.324349] [<ffffffff8151dff9>] driver_attach+0x19/0x20
[ 1.324719] [<ffffffff8151c8e0>] bus_add_driver+0x1a0/0x210
[ 1.325100] [<ffffffff81f8d605>] ?
trace_event_define_fields_switch_mm+0xb3/0xb3
[ 1.325600] [<ffffffff8151e83b>] driver_register+0x5b/0xd0
[ 1.325974] [<ffffffff81f8d605>] ?
trace_event_define_fields_switch_mm+0xb3/0xb3
[ 1.326472] [<ffffffff813ce6fb>] register_virtio_driver+0x1b/0x30
[ 1.326886] [<ffffffff81f8d615>] virtio_gpu_driver_init+0x10/0x12
[ 1.327298] [<ffffffff81f49007>] do_one_initcall+0x8a/0x11a
[ 1.327688] [<ffffffff81f491f8>] kernel_init_freeable+0x161/0x1ec
[ 1.328104] [<ffffffff81950319>] kernel_init+0x9/0x100
[ 1.328455] [<ffffffff8195647f>] ret_from_fork+0x1f/0x40
[ 1.328816] [<ffffffff81950310>] ? rest_init+0x90/0x90
[ 1.329167] Code: c0 75 e6 65 ff 0d 5d 97 e9 7e 74 05 e9 eb fe ff
ff e8 d9 e3 e8 ff e9 e1 fe ff ff 49 8b 02 f6 c4 40 75 0a 49 8b 42 20
a8 01 75 02 <0f> 0b 49 8b 02 31 f6 f6 c4 40 74 04 41 8b 72 6c 4c 89 d7
e8 44
[ 1.330960] RIP [<ffffffff81172c54>] kfree+0x144/0x180
[ 1.331318] RSP <ffff88003e247cc8>
[ 1.331592] ---[ end trace 143836688e11e499 ]---
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