Am 01.12.2017 um 01:23 schrieb Lyude Paul:

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

Acked-by: Christian König christian.koenig@amd.com

Thanks for taking care of this, Christian.

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

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