Patch "drm/amdgpu: check vm ready by amdgpu_vm->evicting flag" has been added to the 5.15-stable tree

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This is a note to let you know that I've just added the patch titled

    drm/amdgpu: check vm ready by amdgpu_vm->evicting flag

to the 5.15-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amdgpu-check-vm-ready-by-amdgpu_vm-evicting-flag.patch
and it can be found in the queue-5.15 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit a49c23a3287d17a6b5994a2f8b3bb0c755bf9d16
Author: Qiang Yu <qiang.yu@xxxxxxx>
Date:   Mon Feb 21 17:53:56 2022 +0800

    drm/amdgpu: check vm ready by amdgpu_vm->evicting flag
    
    [ Upstream commit c1a66c3bc425ff93774fb2f6eefa67b83170dd7e ]
    
    Workstation application ANSA/META v21.1.4 get this error dmesg when
    running CI test suite provided by ANSA/META:
    [drm:amdgpu_gem_va_ioctl [amdgpu]] *ERROR* Couldn't update BO_VA (-16)
    
    This is caused by:
    1. create a 256MB buffer in invisible VRAM
    2. CPU map the buffer and access it causes vm_fault and try to move
       it to visible VRAM
    3. force visible VRAM space and traverse all VRAM bos to check if
       evicting this bo is valuable
    4. when checking a VM bo (in invisible VRAM), amdgpu_vm_evictable()
       will set amdgpu_vm->evicting, but latter due to not in visible
       VRAM, won't really evict it so not add it to amdgpu_vm->evicted
    5. before next CS to clear the amdgpu_vm->evicting, user VM ops
       ioctl will pass amdgpu_vm_ready() (check amdgpu_vm->evicted)
       but fail in amdgpu_vm_bo_update_mapping() (check
       amdgpu_vm->evicting) and get this error log
    
    This error won't affect functionality as next CS will finish the
    waiting VM ops. But we'd better clear the error log by checking
    the amdgpu_vm->evicting flag in amdgpu_vm_ready() to stop calling
    amdgpu_vm_bo_update_mapping() later.
    
    Another reason is amdgpu_vm->evicted list holds all BOs (both
    user buffer and page table), but only page table BOs' eviction
    prevent VM ops. amdgpu_vm->evicting flag is set only for page
    table BOs, so we should use evicting flag instead of evicted list
    in amdgpu_vm_ready().
    
    The side effect of this change is: previously blocked VM op (user
    buffer in "evicted" list but no page table in it) gets done
    immediately.
    
    v2: update commit comments.
    
    Acked-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
    Reviewed-by: Christian König <christian.koenig@xxxxxxx>
    Signed-off-by: Qiang Yu <qiang.yu@xxxxxxx>
    Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
    Cc: stable@xxxxxxxxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 6b15cad78de9d..a33cb2f4d7444 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -768,11 +768,16 @@ int amdgpu_vm_validate_pt_bos(struct amdgpu_device *adev, struct amdgpu_vm *vm,
  * Check if all VM PDs/PTs are ready for updates
  *
  * Returns:
- * True if eviction list is empty.
+ * True if VM is not evicting.
  */
 bool amdgpu_vm_ready(struct amdgpu_vm *vm)
 {
-	return list_empty(&vm->evicted);
+	bool ret;
+
+	amdgpu_vm_eviction_lock(vm);
+	ret = !vm->evicting;
+	amdgpu_vm_eviction_unlock(vm);
+	return ret;
 }
 
 /**



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