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>

1 files changed, 38 insertions, 10 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index e52fc641edfb..53e627970798 100644
--- 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;
 }