[amdgpu] drm/ttm framebuffer race condition into fork()

Mon Jul 25 11:09:33 UTC 2022

Hello Dri-devel,

( Apparently I have issues with subscribing to your
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if you have the time pls manually subscribe me
cause this thing is broken:
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There is yet another race condition happening with ttm objects,
this time with fbdev.

Please consider the following simple code that shows the problem (or
email attached):
https://0x0.st/ojmf.c

The kernel assertion:

[ 2112.472011] ---[ end trace 0000000000000000 ]---
[ 2182.118552] usb 3-2.2.1.4: reset high-speed USB device number 8
using xhci_hcd
[ 2194.632197] ------------[ cut here ]------------
[ 2194.632199] WARNING: CPU: 6 PID: 383 at
drivers/gpu/drm/ttm/ttm_bo_vm.c:352 0xffffffff8169c28f
[ 2194.632201] CPU: 6 PID: 383 Comm: fb Tainted: G        W
5.19.0-rc7+ #22 353afba44cdabdab9fdfaa6990a088718abd5d85
[ 2194.632204] Hardware name: To Be Filled By O.E.M. To Be Filled By
O.E.M./X300M-STX, BIOS L1.72 10/08/2021
[ 2194.632205] RIP: 0010:0xffffffff8169c28f
[ 2194.632206] Code: 48 8d ba 50 01 00 00 b8 01 00 00 00 f0 0f c1 82
50 01 00 00 85 c0 74 16 8d 50 01 09 c2 78 01 c3 be 01 00 00 00 e9 91
47 e5 ff <0f> 0b eb d2 be 02 00 00 00 e9 83 47 e5 ff 0f 1f 00 41 57 41
56 41
[ 2194.632207] RSP: 0018:ffffc90000767d30 EFLAGS: 00010287
[ 2194.632209] RAX: ffff888100a627b8 RBX: ffff888101745ec0 RCX: ffff888102285128
[ 2194.632210] RDX: ffff888102b00058 RSI: 00007f89976fb000 RDI: ffff88811031d440
[ 2194.632211] RBP: ffff88810177c800 R08: ffff888102541138 R09: ffff88811f9d95e0
[ 2194.632212] R10: ffff8887fe2fc000 R11: 0000000000000000 R12: 0000000000000000
[ 2194.632213] R13: ffff888102c5fc00 R14: ffff88811031d390 R15: ffff88811031d440
[ 2194.632213] FS:  00007f89977afb68(0000) GS:ffff8887ded80000(0000)
knlGS:0000000000000000
[ 2194.632214] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 2194.632215] CR2: 00007f8994840000 CR3: 00000001047df000 CR4: 0000000000750ee0
[ 2194.632216] PKRU: 55555554
[ 2194.632217] Call Trace:
[ 2194.632218]  <TASK>
[ 2194.632219]  0xffffffff81040d1e
[ 2194.632220]  0xffffffff8104306b
[ 2194.632221]  0xffffffff81043306
[ 2194.632222]  ? 0xffffffff81608ae6
[ 2194.632222]  0xffffffff810437d1
[ 2194.632223]  0xffffffff81fa1884
[ 2194.632224]  0xffffffff8200006a
[ 2194.632225] RIP: 0033:0x00007f8997749429
[ 2194.632226] Code: 88 00 00 00 31 c0 48 89 e5 48 89 ef e8 e0 b5 00
00 bf ff ff ff ff e8 36 7a fc ff 4c 89 e7 e8 ae bc 01 00 b8 39 00 00
00 0f 05 <48> 89 c3 85 c0 75 50 b8 ba 00 00 00 64 48 8b 14 25 00 00 00
00 0f
[ 2194.632227] RSP: 002b:00007ffee0d808e0 EFLAGS: 00000246 ORIG_RAX:
0000000000000039
[ 2194.632228] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f8997749429
[ 2194.632229] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00007f89977affd4
[ 2194.632230] RBP: 00007ffee0d808e0 R08: 0000000000000000 R09: 0000000000000000
[ 2194.632230] R10: 0000000000000008 R11: 0000000000000246 R12: 00007f89977affd4
[ 2194.632231] R13: 00007f89977afb9c R14: 00007ffee0d809a0 R15: 00007f89977b0a40
[ 2194.632232]  </TASK>

Apparently this commit does not fix it
dbd0da2453c694f2f74651834d90fb280b57f151

Hardware info:
00:00.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Renoir/Cezanne
Root Complex
00:01.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Renoir PCIe
Dummy Host Bridge
00:01.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Renoir PCIe GPP Bridge
00:02.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Renoir PCIe
Dummy Host Bridge
00:02.3 PCI bridge: Advanced Micro Devices, Inc. [AMD] Renoir/Cezanne
PCIe GPP Bridge
00:02.4 PCI bridge: Advanced Micro Devices, Inc. [AMD] Renoir/Cezanne
PCIe GPP Bridge
00:08.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Renoir PCIe
Dummy Host Bridge
00:08.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Renoir Internal
PCIe GPP Bridge to Bus
00:14.0 SMBus: Advanced Micro Devices, Inc. [AMD] FCH SMBus Controller (rev 51)
00:14.3 ISA bridge: Advanced Micro Devices, Inc. [AMD] FCH LPC Bridge (rev 51)
00:18.0 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 0
00:18.1 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 1
00:18.2 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 2
00:18.3 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 3
00:18.4 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 4
00:18.5 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 5
00:18.6 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 6
00:18.7 Host bridge: Advanced Micro Devices, Inc. [AMD] Cezanne Data
Fabric; Function 7
04:00.0 VGA compatible controller: Advanced Micro Devices, Inc.
[AMD/ATI] Cezanne (rev c8)
04:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Renoir
Radeon High Definition Audio Controller

Kyryl
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