drm/amdgpu: prevent get_user_pages recursion

Remember the tasks which are inside get_user_pages()
and ignore MMU callbacks from there.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index e52fc64..53e6279 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -494,13 +494,20 @@ static void amdgpu_ttm_io_mem_free(struct ttm_bo_device *bdev, struct ttm_mem_re
 /*
  * TTM backend functions.
  */
+struct amdgpu_ttm_gup_task_list {
+       struct list_head        list;
+       struct task_struct      *task;
+};
+
 struct amdgpu_ttm_tt {
-       struct ttm_dma_tt               ttm;
-       struct amdgpu_device            *adev;
-       u64                             offset;
-       uint64_t                        userptr;
-       struct mm_struct                *usermm;
-       uint32_t                        userflags;
+       struct ttm_dma_tt       ttm;
+       struct amdgpu_device    *adev;
+       u64                     offset;
+       uint64_t                userptr;
+       struct mm_struct        *usermm;
+       uint32_t                userflags;
+       spinlock_t              guptasklock;
+       struct list_head        guptasks;
 };
 
 /* prepare the sg table with the user pages */
@@ -530,9 +537,20 @@ static int amdgpu_ttm_tt_pin_userptr(struct ttm_tt *ttm)
                unsigned num_pages = ttm->num_pages - pinned;
                uint64_t userptr = gtt->userptr + pinned * PAGE_SIZE;
                struct page **pages = ttm->pages + pinned;
+               struct amdgpu_ttm_gup_task_list guptask;
+
+               guptask.task = current;
+               spin_lock(&gtt->guptasklock);
+               list_add(&guptask.list, &gtt->guptasks);
+               spin_unlock(&gtt->guptasklock);
 
                r = get_user_pages(current, current->mm, userptr, num_pages,
                                   write, 0, pages, NULL);
+
+               spin_lock(&gtt->guptasklock);
+               list_del(&guptask.list);
+               spin_unlock(&gtt->guptasklock);
+
                if (r < 0)
                        goto release_pages;
 
@@ -783,6 +801,9 @@ int amdgpu_ttm_tt_set_userptr(struct ttm_tt *ttm, uint64_t addr,
        gtt->userptr = addr;
        gtt->usermm = current->mm;
        gtt->userflags = flags;
+       spin_lock_init(&gtt->guptasklock);
+       INIT_LIST_HEAD(&gtt->guptasks);
+
        return 0;
 }
 
@@ -800,18 +821,25 @@ bool amdgpu_ttm_tt_affect_userptr(struct ttm_tt *ttm, unsigned long start,
                                  unsigned long end)
 {
        struct amdgpu_ttm_tt *gtt = (void *)ttm;
+       struct amdgpu_ttm_gup_task_list *entry;
        unsigned long size;
 
-       if (gtt == NULL)
-               return false;
-
-       if (gtt->ttm.ttm.state != tt_bound || !gtt->userptr)
+       if (gtt == NULL || !gtt->userptr)
                return false;
 
        size = (unsigned long)gtt->ttm.ttm.num_pages * PAGE_SIZE;
        if (gtt->userptr > end || gtt->userptr + size <= start)
                return false;
 
+       spin_lock(&gtt->guptasklock);
+       list_for_each_entry(entry, &gtt->guptasks, list) {
+               if (entry->task == current) {
+                       spin_unlock(&gtt->guptasklock);
+                       return false;
+               }
+       }
+       spin_unlock(&gtt->guptasklock);
+
        return true;
 }