On 10/20/22 06:23, kernel test robot wrote:
> Greeting,
> 
> FYI, we noticed WARNING:at_drivers/gpu/drm/drm_gem.c:#drm_gem_vunmap due to commit (built with clang-14):
> 
> commit: 79e2cf2e7a193473dfb0da3b9b869682b43dc60f ("drm/gem: Take reservation lock for vmap/vunmap operations")
> git://anongit.freedesktop.org/drm/drm-misc drm-misc-next
> 
> in testcase: boot
> 
> on test machine: qemu-system-i386 -enable-kvm -cpu SandyBridge -smp 2 -m 4G
> 
> caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):
> 
> 
> [    5.483437][    T1] ------------[ cut here ]------------
> [    5.484265][    T1] WARNING: CPU: 1 PID: 1 at drivers/gpu/drm/drm_gem.c:1191 drm_gem_vunmap+0x50/0xa0
> [    5.485640][    T1] Modules linked in:
> [    5.486298][    T1] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.0.0-rc2-00895-g79e2cf2e7a19 #1 d064e7e3c98977ac595341fa8e33617722110e67
> [    5.488083][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014
> [    5.489590][    T1] EIP: drm_gem_vunmap+0x50/0xa0
> [    5.490359][    T1] Code: ff ff e8 f3 29 97 00 85 c0 0f 94 c3 eb 02 31 db 0f b6 fb b8 90 74 8e c3 89 fa 31 c9 6a 00 e8 77 ca 7b ff 83 c4 04 84 db 74 02 <0f> 0b b8 a8 74 8e c3 89 fa 31 c9 6a 00 e8 5e ca 7b ff 83 c4 04 83
> [    5.493049][    T1] EAX: c38e74a0 EBX: ffffff01 ECX: 00000000 EDX: 00000001
> [    5.494179][    T1] ESI: c6d8b870 EDI: 00000001 EBP: c46d7d34 ESP: c46d7d24
> [    5.495296][    T1] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010202
> [    5.496530][    T1] CR0: 80050033 CR2: 00000000 CR3: 03aa0000 CR4: 000406d0
> [    5.497647][    T1] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
> [    5.498759][    T1] DR6: fffe0ff0 DR7: 00000400
> [    5.499486][    T1] Call Trace:
> [    5.500104][    T1]  drm_client_buffer_delete+0x1d/0x90
> [    5.500877][    T1]  drm_client_framebuffer_delete+0x37/0x60
> [    5.501805][    T1]  drm_fbdev_cleanup+0x80/0x90
> [    5.502653][    T1]  drm_fbdev_client_hotplug+0x1b6/0x210
> [    5.503585][    T1]  drm_fbdev_generic_setup+0x143/0x1a0
> [    5.504571][    T1]  vkms_init+0x23f/0x244
> [    5.505338][    T1]  ? vgem_init+0x133/0x133
> [    5.506130][    T1]  do_one_initcall+0x10e/0x210
> [    5.506976][    T1]  ? vgem_init+0x133/0x133
> [    5.507775][    T1]  do_initcall_level+0x80/0x92
> [    5.508630][    T1]  do_initcalls+0x41/0x6f
> [    5.509386][    T1]  do_basic_setup+0x17/0x19
> [    5.510106][    T1]  kernel_init_freeable+0xb4/0xe5
> [    5.510970][    T1]  ? rest_init+0x180/0x180
> [    5.511745][    T1]  kernel_init+0x17/0x180
> [    5.512522][    T1]  ret_from_fork+0x19/0x24
> [    5.513333][    T1] irq event stamp: 118087
> [    5.514101][    T1] hardirqs last  enabled at (118097): [<c1107774>] __up_console_sem+0x64/0xb0
> [    5.515620][    T1] hardirqs last disabled at (118110): [<c110775b>] __up_console_sem+0x4b/0xb0
> [    5.517061][    T1] softirqs last  enabled at (117834): [<c236bd86>] __do_softirq+0x2c6/0x329
> [    5.518391][    T1] softirqs last disabled at (117825): [<c102bb62>] do_softirq_own_stack+0x22/0x30
> [    5.519760][    T1] ---[ end trace 0000000000000000 ]---

That's a good catch, I missed to touch drm_client.c. At a quick glance
will be fine to switch it to the unlocked drm_gem_vun/map functions.

-- 
Best regards,
Dmitry