[PATCH v3] drm/ttm: fix error handling if no BO can be swapped out

[PATCH v3] drm/ttm: fix error handling if no BO can be swapped out

[Shiwu Zhang]

In case that all pre-allocated BOs are busy, just continue to populate
BOs since likely half of system memory in total is still free.

Signed-off-by: Shiwu Zhang <shiwu.zhang@amd.com>
---
 drivers/gpu/drm/ttm/ttm_device.c | 2 +-
 drivers/gpu/drm/ttm/ttm_tt.c     | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index 1f2024164d72..a48fe4dccd61 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -112,7 +112,7 @@ int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags)
 {
 	struct ttm_global *glob = &ttm_glob;
 	struct ttm_device *bdev;
-	int ret = -EBUSY;
+	int ret;
 
 	mutex_lock(&ttm_global_mutex);
 	list_for_each_entry(bdev, &glob->device_list, device_list) {
diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 48c407cff112..539e0232cb3b 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -329,6 +329,8 @@ int ttm_tt_populate(struct ttm_device *bdev,
 	       ttm_dma32_pages_limit) {
 
 		ret = ttm_global_swapout(ctx, GFP_KERNEL);
+		if (ret == 0)
+			break;
 		if (ret < 0)
 			goto error;
 	}
-- 
2.17.1

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Re: [PATCH v3] drm/ttm: fix error handling if no BO can be swapped out

[Christian König]

Am 22.04.21 um 12:25 schrieb Shiwu Zhang:
> In case that all pre-allocated BOs are busy, just continue to populate

I'm not a native speaker of English either, but I think that should read 
"previously allocated".

> BOs since likely half of system memory in total is still free.
>
> Signed-off-by: Shiwu Zhang <shiwu.zhang@amd.com>

> ---
>   drivers/gpu/drm/ttm/ttm_device.c | 2 +-
>   drivers/gpu/drm/ttm/ttm_tt.c     | 2 ++
>   2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
> index 1f2024164d72..a48fe4dccd61 100644
> --- a/drivers/gpu/drm/ttm/ttm_device.c
> +++ b/drivers/gpu/drm/ttm/ttm_device.c
> @@ -112,7 +112,7 @@ int ttm_global_swapout(struct ttm_operation_ctx *ctx, gfp_t gfp_flags)
>   {
>   	struct ttm_global *glob = &ttm_glob;
>   	struct ttm_device *bdev;
> -	int ret = -EBUSY;
> +	int ret;

Oh, we have been inconsistent here?

In this case we should indeed zero initialize the variable and also fix 
the only other user in vmwgfx!

Going to take care of this myself.

Thanks for the help,
Christian.

>   
>   	mutex_lock(&ttm_global_mutex);
>   	list_for_each_entry(bdev, &glob->device_list, device_list) {
> diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
> index 48c407cff112..539e0232cb3b 100644
> --- a/drivers/gpu/drm/ttm/ttm_tt.c
> +++ b/drivers/gpu/drm/ttm/ttm_tt.c
> @@ -329,6 +329,8 @@ int ttm_tt_populate(struct ttm_device *bdev,
>   	       ttm_dma32_pages_limit) {
>   
>   		ret = ttm_global_swapout(ctx, GFP_KERNEL);
> +		if (ret == 0)
> +			break;
>   		if (ret < 0)
>   			goto error;
>   	}

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