drm-kmod kernel panic on 12.0

[José Pérez]

Hi,
I get these with AMD hardware on 12.0 and 
drm-fbsd12.0-kmod-4.16.g20181215:
panic: BUG ON ret failed at 
/wrkdirs/usr/ports/graphics/drm-fbsd12.0-kmod/work/kms-drm-71fcc9f/drivers/gpu/drm/ttm/ttm_tt.c:259
cpuid = 1
time = 1549320271
KDB: stack backtrace:
#0 0xffffffff80bf0857 at kdb_backtrace+0x67
#1 0xffffffff80ba47d3 at vpanic+0x1a3
#2 0xffffffff80ba4623 at panic+0x43
#3 0xffffffff829d88e3 at ttm_tt_destroy+0xb3
#4 0xffffffff829dd92a at ttm_bo_cleanup_refs+0x1fa
#5 0xffffffff829dca9a at ttm_bo_delayed_delete+0x1aa
#6 0xffffffff829dcc9a at ttm_bo_delayed_workqueue+0x1a
#7 0xffffffff82a14cd4 at linux_work_fn+0xf4
#8 0xffffffff80c02b14 at taskqueue_run_locked+0x154
#9 0xffffffff80c03ea8 at taskqueue_thread_loop+0x98
#10 0xffffffff80b65453 at fork_exit+0x83
#11 0xffffffff8105a1fe at fork_trampoline+0xe
Uptime: 4m27s
Dumping 3531 MB (6 chunks)
   chunk 0: 1MB (159 pages) ... ok
   chunk 1: 2891MB (739869 pages) 2875 2859 2843 2827 2811 2795 2779 2763 
2747 2731 2715 2699 2683 2667 2651 2635 2619 2603 2587 2571 2555 2539 
2523 2507 2491 2475 2459 2443 2427 2411 2395 2379 2363 2347 2331 2315 
2299 2283 2267 2251 2235 2219 2203 2187 2171 2155 2139 2123 2107 2091 
2075 2059 2043 2027 2011 1995 1979 1963 1947 1931 1915 1899 1883 1867 
1851 1835 1819 1803 1787 1771 1755 1739 1723 1707 1691 1675 1659 1643 
1627 1611 1595 1579 1563 1547 1531 1515 1499 1483 1467 1451 1435 1419 
1403 1387 1371 1355 1339 1323 1307 1291 1275 1259 1243 1227 1211 1195 
1179 1163 1147 1131 1115 1099 1083 1067 1051 1035 1019 1003 987 971 955 
939 923 907 891 875 859 843 827 811 795 779 763 747 731 715 699 683 667 
651 635 619 603 587 571 555 539 523 507 491 475 459 443 427 411 395 379 
363 347 331 315 299 283 267 251 235 219 203 187 171 155 139 123 107 91 
75 59 43 27 11 ... ok
   chunk 2: 1MB (94 pages) ... ok
   chunk 3: 144MB (36864 pages) 129 113 97 81 65 49 33 17 1 ... ok
   chunk 4: 1MB (1 pages) ... ok
   chunk 5: 496MB (126976 pages) 481 465 449 433 417 401 385 369 353 337 
321 305 289 273 257 241 225 209 193 177 161 145 129 113 97 81 65 49 33 
17

__curthread () at ./machine/pcpu.h:230
230             __asm("movq %%gs:%P1,%0" : "=r" (td) : "n" 
(OFFSETOF_CURTHREAD));
(kgdb) list
225     static __inline __pure2 struct thread *
226     __curthread(void)
227     {
228             struct thread *td;
229
230             __asm("movq %%gs:%P1,%0" : "=r" (td) : "n" 
(OFFSETOF_CURTHREAD));
231             return (td);
232     }
233     #ifdef __clang__
234     #pragma clang diagnostic pop
(kgdb)


Any suggestion?

Thank you.

BR/

-- 
José Pérez