I haven't gone to see where it started, but as of late a good number of
pretty nasty deadlock issues have appeared with the kernel. Easy
reproduction recipe on a laptop with i915/amdgpu prime with lockdep enabled:
DRI_PRIME=1 glxinfo
Additionally, some more race conditions exist that I've managed to
trigger with piglit and lockdep enabled after applying these patches:
=============================
WARNING: suspicious RCU usage
4.14.3Lyude-Test+ #2 Not tainted
-----------------------------
./include/linux/reservation.h:216 suspicious rcu_dereference_protected() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by ext_image_dma_b/27451:
#0: (reservation_ww_class_mutex){+.+.}, at: [<ffffffffa034f2ff>] ttm_bo_unref+0x9f/0x3c0 [ttm]
stack backtrace:
CPU: 0 PID: 27451 Comm: ext_image_dma_b Not tainted 4.14.3Lyude-Test+ #2
Hardware name: HP HP ZBook 15 G4/8275, BIOS P70 Ver. 01.02 06/09/2017
Call Trace:
dump_stack+0x8e/0xce
lockdep_rcu_suspicious+0xc5/0x100
reservation_object_copy_fences+0x292/0x2b0
? ttm_bo_unref+0x9f/0x3c0 [ttm]
ttm_bo_unref+0xbd/0x3c0 [ttm]
amdgpu_bo_unref+0x2a/0x50 [amdgpu]
amdgpu_gem_object_free+0x4b/0x50 [amdgpu]
drm_gem_object_free+0x1f/0x40 [drm]
drm_gem_object_put_unlocked+0x40/0xb0 [drm]
drm_gem_object_handle_put_unlocked+0x6c/0xb0 [drm]
drm_gem_object_release_handle+0x51/0x90 [drm]
drm_gem_handle_delete+0x5e/0x90 [drm]
? drm_gem_handle_create+0x40/0x40 [drm]
drm_gem_close_ioctl+0x20/0x30 [drm]
drm_ioctl_kernel+0x5d/0xb0 [drm]
drm_ioctl+0x2f7/0x3b0 [drm]
? drm_gem_handle_create+0x40/0x40 [drm]
? trace_hardirqs_on_caller+0xf4/0x190
? trace_hardirqs_on+0xd/0x10
amdgpu_drm_ioctl+0x4f/0x90 [amdgpu]
do_vfs_ioctl+0x93/0x670
? __fget+0x108/0x1f0
SyS_ioctl+0x79/0x90
entry_SYSCALL_64_fastpath+0x23/0xc2
I've also added the relevant fixes for the issue mentioned above.
Christian König (3):
drm/ttm: fix ttm_bo_cleanup_refs_or_queue once more
dma-buf: make reservation_object_copy_fences rcu save
drm/amdgpu: reserve root PD while releasing it
Michel Dänzer (1):
drm/ttm: Always and only destroy bo->ttm_resv in ttm_bo_release_list
drivers/dma-buf/reservation.c | 56 +++++++++++++++++++++++++---------
drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 13 ++++++--
drivers/gpu/drm/ttm/ttm_bo.c | 43 +++++++++++++-------------
3 files changed, 74 insertions(+), 38 deletions(-)
--
2.14.3