Locking mutex in different orders just screams for deadlocks, and some testing showed that it is actually quite easy to trigger them.
Signed-off-by: Christian König deathsimple@vodafone.de Cc: stable@vger.kernel.org --- drivers/gpu/drm/radeon/radeon_gart.c | 19 ++++++++++++------- 1 file changed, 12 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/radeon/radeon_gart.c b/drivers/gpu/drm/radeon/radeon_gart.c index 79db56e..59d4493 100644 --- a/drivers/gpu/drm/radeon/radeon_gart.c +++ b/drivers/gpu/drm/radeon/radeon_gart.c @@ -476,12 +476,18 @@ int radeon_vm_bo_add(struct radeon_device *rdev,
mutex_lock(&vm->mutex); if (last_pfn > vm->last_pfn) { - /* grow va space 32M by 32M */ - unsigned align = ((32 << 20) >> 12) - 1; + /* release mutex and lock in right order */ + mutex_unlock(&vm->mutex); radeon_mutex_lock(&rdev->cs_mutex); - radeon_vm_unbind_locked(rdev, vm); + mutex_lock(&vm->mutex); + /* and check again */ + if (last_pfn > vm->last_pfn) { + /* grow va space 32M by 32M */ + unsigned align = ((32 << 20) >> 12) - 1; + radeon_vm_unbind_locked(rdev, vm); + vm->last_pfn = (last_pfn + align) & ~align; + } radeon_mutex_unlock(&rdev->cs_mutex); - vm->last_pfn = (last_pfn + align) & ~align; } head = &vm->va; last_offset = 0; @@ -595,8 +601,8 @@ int radeon_vm_bo_rmv(struct radeon_device *rdev, if (bo_va == NULL) return 0;
- mutex_lock(&vm->mutex); radeon_mutex_lock(&rdev->cs_mutex); + mutex_lock(&vm->mutex); radeon_vm_bo_update_pte(rdev, vm, bo, NULL); radeon_mutex_unlock(&rdev->cs_mutex); list_del(&bo_va->vm_list); @@ -641,9 +647,8 @@ void radeon_vm_fini(struct radeon_device *rdev, struct radeon_vm *vm) struct radeon_bo_va *bo_va, *tmp; int r;
- mutex_lock(&vm->mutex); - radeon_mutex_lock(&rdev->cs_mutex); + mutex_lock(&vm->mutex); radeon_vm_unbind_locked(rdev, vm); radeon_mutex_unlock(&rdev->cs_mutex);