radeon-related (?) panics on -current

[Timo Buhrmester <timo%math.uni-bonn.de@localhost>]

Hi,

My machine spontaneously panics every 2-5 days as of my switch from -stable to -current; this time I caught the backtrace on the serial console:

| panic: kernel diagnostic assertion "mo->mo_refcnt > 0" failed: file "/usr/src.head/sys/kern/kern_mutex_obj.c", line 135 mutex_obj_free: lock 0xfffffe80983f1e00: mo->mo_refcnt (0) == 0
| cpu0: Begin traceback...
| vpanic() at netbsd:vpanic+0x13c
| kern_assert() at netbsd:kern_assert+0x4f
| mutex_obj_free() at netbsd:mutex_obj_free+0x9d
| uvm_obj_setlock() at netbsd:uvm_obj_setlock+0x1a
| ttm_bo_add_ttm() at netbsd:ttm_bo_add_ttm+0x94
| ttm_bo_handle_move_mem() at netbsd:ttm_bo_handle_move_mem+0x600
| ttm_mem_evict_first() at netbsd:ttm_mem_evict_first+0x4e0
| ttm_bo_mem_space() at netbsd:ttm_bo_mem_space+0x269
| ttm_bo_validate() at netbsd:ttm_bo_validate+0x1b1
| ttm_bo_init() at netbsd:ttm_bo_init+0x215
| radeon_bo_create() at netbsd:radeon_bo_create+0x15d
| radeon_gem_object_create() at netbsd:radeon_gem_object_create+0x97
| radeon_gem_create_ioctl() at netbsd:radeon_gem_create_ioctl+0x5f
| drm_ioctl() at netbsd:drm_ioctl+0x122
| sys_ioctl() at netbsd:sys_ioctl+0x17e
| syscall() at netbsd:syscall+0x9a
| --- syscall (number 54) --- 
| 7f7ff40cf7fa:
| cpu0: End traceback...

It's a desktop, normally running not much besides a lot of terminal emulators, a lightweight window manager and firefox
On NetBSD 6, using the same hardware, the machine ran very stable with uptimes in excess of 100 days.

| $ dmesg | grep -i 'radeon\|drm'
| radeon0 at pci1 dev 5 function 0: vendor 1002 product 9610 (rev. 0x00)
| drm: initializing kernel modesetting (RS780 0x1002:0x9610 0x1043:0x82F1).
| drm: register mmio base: 0xfe9f0000
| drm: register mmio size: 65536
| drm kern info: ATOM BIOS: 113
| radeon0: info: VRAM: 256M 0x00000000C0000000 - 0x00000000CFFFFFFF (256M used)
| radeon0: info: GTT: 512M 0x00000000A0000000 - 0x00000000BFFFFFFF
| drm: Detected VRAM RAM=100M, BAR=256M
| drm: RAM width 32bits DDR
| drm: radeon: 256M of VRAM memory ready
| drm: radeon: 512M of GTT memory ready.
| drm: Loading RS780 Microcode
| drm: GART: num cpu pages 131072, num gpu pages 131072
| drm: PCIE GART of 512M enabled (table at 0x00000000C0040000).
| radeon0: info: WB enabled
| radeon0: info: fence driver on ring 0 use gpu addr 0x00000000a0000c00 and cpu addr 0x0xffff800032d56c00
| drm: Supports vblank timestamp caching Rev 2 (21.10.2013).
| drm: Driver supports precise vblank timestamp query.
| radeon0: interrupting at ioapic0 pin 18 (radeon)
| drm: radeon: irq initialized.
| drm: ring test on 0 succeeded in 1 usecs
| drm: ib test on ring 0 succeeded in 0 usecs
| drm: Radeon Display Connectors
| drm: Connector 0:
| drm:   VGA-1
| drm:   DDC: 0x7e40 0x7e40 0x7e44 0x7e44 0x7e48 0x7e48 0x7e4c 0x7e4c
| drm:   Encoders:
| drm:     CRT1: INTERNAL_KLDSCP_DAC1
| drm: Connector 1:
| drm:   HDMI-A-1
| drm:   HPD3
| drm:   DDC: 0x7e50 0x7e50 0x7e54 0x7e54 0x7e58 0x7e58 0x7e5c 0x7e5c
| drm:   Encoders:
| drm:     DFP3: INTERNAL_KLDSCP_LVTMA
| radeondrmkmsfb0 at radeon0
| radeon0: info: registered panic notifier
| radeondrmkmsfb0: framebuffer at 0xffff800033080000, size 1280x1024, depth 32, stride 5120
| wsdisplay0 at radeondrmkmsfb0 kbdmux 1

What other information could be useful for diagnosing this?

Cheers,
Timo