Encountering a taint issue during the unloading of gpu_sched
due to the fence not being released/put. In this context,
amdgpu_vm_clear_freed is responsible for creating a job to
update the page table (PT). It allocates kmem_cache for
drm_sched_fence and returns the finished fence associated
with job->base.s_fence. In case of Usermode queue this finished
fence is added to the timeline sync object through
amdgpu_gem_update_bo_mapping, which is utilized by user
space to ensure the completion of the PT update.

[  508.900587] 
=============================================================================
[  508.900605] BUG drm_sched_fence (Tainted: G                 N): Objects 
remaining in drm_sched_fence on __kmem_cache_shutdown()
[  508.900617] 
-----------------------------------------------------------------------------

[  508.900627] Slab 0xffffe0cc04548780 objects=32 used=2 fp=0xffff8ea81521f000 
flags=0x17ffffc0000240(workingset|head|node=0|zone=2|lastcpupid=0x1fffff)
[  508.900645] CPU: 3 UID: 0 PID: 2337 Comm: rmmod Tainted: G                 N 
6.12.0+ #1
[  508.900651] Tainted: [N]=TEST
[  508.900653] Hardware name: Gigabyte Technology Co., Ltd. X570 AORUS 
ELITE/X570 AORUS ELITE, BIOS F34 06/10/2021
[  508.900656] Call Trace:
[  508.900659]  <TASK>
[  508.900665]  dump_stack_lvl+0x70/0x90
[  508.900674]  dump_stack+0x14/0x20
[  508.900678]  slab_err+0xcb/0x110
[  508.900687]  ? srso_return_thunk+0x5/0x5f
[  508.900692]  ? try_to_grab_pending+0xd3/0x1d0
[  508.900697]  ? srso_return_thunk+0x5/0x5f
[  508.900701]  ? mutex_lock+0x17/0x50
[  508.900708]  __kmem_cache_shutdown+0x144/0x2d0
[  508.900713]  ? flush_rcu_work+0x50/0x60
[  508.900719]  kmem_cache_destroy+0x46/0x1f0
[  508.900728]  drm_sched_fence_slab_fini+0x19/0x970 [gpu_sched]
[  508.900736]  __do_sys_delete_module.constprop.0+0x184/0x320
[  508.900744]  ? srso_return_thunk+0x5/0x5f
[  508.900747]  ? debug_smp_processor_id+0x1b/0x30
[  508.900754]  __x64_sys_delete_module+0x16/0x20
[  508.900758]  x64_sys_call+0xdf/0x20d0
[  508.900763]  do_syscall_64+0x51/0x120
[  508.900769]  entry_SYSCALL_64_after_hwframe+0x76/0x7e

v2: call dma_fence_put in amdgpu_gem_va_update_vm
v3: Addressed review comments from Christian.
    - calling amdgpu_gem_update_timeline_node before switch.
    - puting a dma_fence in case of error or !timeline_syncobj.

Cc: Alex Deucher <alexander.deuc...@amd.com>
Cc: Christian König <christian.koe...@amd.com>
Cc: Shashank Sharma <shashank.sha...@amd.com>
Cc: Sunil Khatri <sunil.kha...@amd.com>
Signed-off-by: Le Ma <le...@amd.com>
Signed-off-by: Arvind Yadav <arvind.ya...@amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 33 +++++++++++++------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
index 8b67aae6c2fe..40522b4f331b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
@@ -125,9 +125,6 @@ amdgpu_gem_update_bo_mapping(struct drm_file *filp,
        struct amdgpu_vm *vm = &fpriv->vm;
        struct dma_fence *last_update;
 
-       if (!syncobj)
-               return;
-
        /* Find the last update fence */
        switch (operation) {
        case AMDGPU_VA_OP_MAP:
@@ -839,6 +836,7 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
        struct drm_exec exec;
        uint64_t va_flags;
        uint64_t vm_size;
+       int syncobj_status;
        int r = 0;
 
        if (args->va_address < AMDGPU_VA_RESERVED_BOTTOM) {
@@ -931,6 +929,12 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void *data,
                bo_va = NULL;
        }
 
+       syncobj_status = amdgpu_gem_update_timeline_node(filp,
+                                       args->vm_timeline_syncobj_out,
+                                       args->vm_timeline_point,
+                                       &timeline_syncobj,
+                                       &timeline_chain);
+
        switch (args->operation) {
        case AMDGPU_VA_OP_MAP:
                va_flags = amdgpu_gem_va_map_flags(adev, args->flags);
@@ -957,22 +961,19 @@ int amdgpu_gem_va_ioctl(struct drm_device *dev, void 
*data,
                break;
        }
        if (!r && !(args->flags & AMDGPU_VM_DELAY_UPDATE) && !adev->debug_vm) {
-
-               r = amdgpu_gem_update_timeline_node(filp,
-                                                   
args->vm_timeline_syncobj_out,
-                                                   args->vm_timeline_point,
-                                                   &timeline_syncobj,
-                                                   &timeline_chain);
-
                fence = amdgpu_gem_va_update_vm(adev, &fpriv->vm, bo_va,
                                                args->operation);
 
-               if (!r)
-                       amdgpu_gem_update_bo_mapping(filp, bo_va,
-                                                    args->operation,
-                                                    args->vm_timeline_point,
-                                                    fence, timeline_syncobj,
-                                                    timeline_chain);
+               if (syncobj_status || !timeline_syncobj) {
+                       dma_fence_put(fence);
+                       goto error;
+               }
+
+               amdgpu_gem_update_bo_mapping(filp, bo_va,
+                                            args->operation,
+                                            args->vm_timeline_point,
+                                            fence, timeline_syncobj,
+                                            timeline_chain);
        }
 
 error:
-- 
2.34.1

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