Re: [PATCH] drm/ttm: fix missing NULL check in ttm_device_swapout

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Am 04.06.22 um 00:44 schrieb Felix Kuehling:
[+amd-gfx]


On 2022-06-03 15:37, Felix Kuehling wrote:

On 2022-06-03 06:46, Christian König wrote:
Resources about to be destructed are not tied to BOs any more.
I've been seeing a backtrace in that area with a patch series I'm working on, but didn't have enough time to track it down yet. I'll try if this patch fixes it.

The patch doesn't apply on amd-staging-drm-next. I made the following change instead, which fixes my problem (and I do see the pr_err being triggered):

--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -157,6 +157,10 @@ int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
                        list_for_each_entry(bo, &man->lru[j], lru) {
                                uint32_t num_pages = PFN_UP(bo->base.size);

+                               if (!bo->resource) {
+                                       pr_err("### bo->resource is NULL\n");
+                                       continue;
+                               }

Yeah, that should be functional identical.

Can I get an rb for that? Going to provide backports to older kernels as well then.

Regards,
Christian.

ret = ttm_bo_swapout(bo, ctx, gfp_flags);
                                /* ttm_bo_swapout has dropped the lru_lock */
                                if (!ret)


Regards,
  Felix



Signed-off-by: Christian König <christian.koenig@xxxxxxx>
---
  drivers/gpu/drm/ttm/ttm_device.c | 6 +++++-
  1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index a0562ab386f5..e7147e304637 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -156,8 +156,12 @@ int ttm_device_swapout(struct ttm_device *bdev, struct ttm_operation_ctx *ctx,
            ttm_resource_manager_for_each_res(man, &cursor, res) {
              struct ttm_buffer_object *bo = res->bo;
-            uint32_t num_pages = PFN_UP(bo->base.size);
+            uint32_t num_pages;
  +            if (!bo)
+                continue;
+
+            num_pages = PFN_UP(bo->base.size);
              ret = ttm_bo_swapout(bo, ctx, gfp_flags);
              /* ttm_bo_swapout has dropped the lru_lock */
              if (!ret)




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