On Wed, 2019-05-22 at 11:55 +0200, Lucas Stach wrote:
> The devcoredump needs to operate on a stable state of the MMU while
> it is writing the MMU state to the coredump. The missing lock
> allowed both the userspace submit, as well as the GPU job finish
> paths to mutate the MMU state while a coredump is under way.
>
> Fixes: a8c21a5451d8 (drm/etnaviv: add initial etnaviv DRM driver)
> Reported-by: David Jander <david@xxxxxxxxxxx>
> Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> Tested-by: David Jander <david@xxxxxxxxxxx>
Reviewed-by: Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/etnaviv/etnaviv_dump.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_dump.c b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> index 33854c94cb85..515515ef24f9 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> @@ -125,6 +125,8 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
> return;
> etnaviv_dump_core = false;
>
> + mutex_lock(&gpu->mmu->lock);
> +
> mmu_size = etnaviv_iommu_dump_size(gpu->mmu);
>
> /* We always dump registers, mmu, ring and end marker */
> @@ -167,6 +169,7 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
> iter.start = __vmalloc(file_size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
> PAGE_KERNEL);
> if (!iter.start) {
> + mutex_unlock(&gpu->mmu->lock);
> dev_warn(gpu->dev, "failed to allocate devcoredump file\n");
> return;
> }
> @@ -234,6 +237,8 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
> obj->base.size);
> }
>
> + mutex_unlock(&gpu->mmu->lock);
> +
> etnaviv_core_dump_header(&iter, ETDUMP_BUF_END, iter.data);
>
> dev_coredumpv(gpu->dev, iter.start, iter.data - iter.start, GFP_KERNEL);
regards
Philipp
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