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drm/amdgpu: Fix race condition in amdgpu_mn_unregister 

Exchange locking order of adev->mn_lock and mm_sem, so that
rmn->mm->mmap_sem can be taken safely, protected by adev->mn_lock,
when amdgpu_mn_destroy runs concurrently.

Signed-off-by: Felix Kuehling <Felix.Kuehling@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
This commit is contained in:
Felix Kuehling 2016-02-16 15:29:23 -05:00 committed by Alex Deucher
parent 418aa0c296
commit b8ea378346
1 changed files with 13 additions and 10 deletions
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23
drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
View File

@ -71,12 +71,11 @@ static void amdgpu_mn_destroy(struct work_struct *work)
struct amdgpu_mn_node *node, *next_node;
struct amdgpu_bo *bo, *next_bo;
down_write(&rmn->mm->mmap_sem);
mutex_lock(&adev->mn_lock);
down_write(&rmn->mm->mmap_sem);
hash_del(&rmn->node);
rbtree_postorder_for_each_entry_safe(node, next_node, &rmn->objects,
it.rb) {
interval_tree_remove(&node->it, &rmn->objects);
list_for_each_entry_safe(bo, next_bo, &node->bos, mn_list) {
bo->mn = NULL;
@ -84,8 +83,8 @@ static void amdgpu_mn_destroy(struct work_struct *work)
}
kfree(node);
}
mutex_unlock(&adev->mn_lock);
up_write(&rmn->mm->mmap_sem);
mutex_unlock(&adev->mn_lock);
mmu_notifier_unregister_no_release(&rmn->mn, rmn->mm);
kfree(rmn);
}
@ -182,8 +181,8 @@ static struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev)
struct amdgpu_mn *rmn;
int r;
down_write(&mm->mmap_sem);
mutex_lock(&adev->mn_lock);
down_write(&mm->mmap_sem);
hash_for_each_possible(adev->mn_hash, rmn, node, (unsigned long)mm)
if (rmn->mm == mm)
@ -207,14 +206,14 @@ static struct amdgpu_mn *amdgpu_mn_get(struct amdgpu_device *adev)
hash_add(adev->mn_hash, &rmn->node, (unsigned long)mm);
release_locks:
mutex_unlock(&adev->mn_lock);
up_write(&mm->mmap_sem);
mutex_unlock(&adev->mn_lock);
return rmn;
free_rmn:
mutex_unlock(&adev->mn_lock);
up_write(&mm->mmap_sem);
mutex_unlock(&adev->mn_lock);
kfree(rmn);
return ERR_PTR(r);
@ -288,14 +287,18 @@ int amdgpu_mn_register(struct amdgpu_bo *bo, unsigned long addr)
void amdgpu_mn_unregister(struct amdgpu_bo *bo)
{
struct amdgpu_device *adev = bo->adev;
struct amdgpu_mn *rmn = bo->mn;
struct amdgpu_mn *rmn;
struct list_head *head;
if (rmn == NULL)
mutex_lock(&adev->mn_lock);
rmn = bo->mn;
if (rmn == NULL) {
mutex_unlock(&adev->mn_lock);
return;
}
down_write(&rmn->mm->mmap_sem);
mutex_lock(&adev->mn_lock);
/* save the next list entry for later */
head = bo->mn_list.next;
@ -310,6 +313,6 @@ void amdgpu_mn_unregister(struct amdgpu_bo *bo)
kfree(node);
}
mutex_unlock(&adev->mn_lock);
up_write(&rmn->mm->mmap_sem);
mutex_unlock(&adev->mn_lock);
}