Re: [PATCH v10 5/7] drm/tyr: add a kernel buffer object

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Resource leak: `KernelBo::drop` permanently leaks the GEM buffer object and its virtual mapping if `vm.unmap_range()` fails.
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--- Patch [5]: [PATCH v10 5/7] drm/tyr: add a kernel buffer object ---
commit f17ba69672f18401371cf98a1da7881e0b938c23
Author: Deborah Brouwer <deborah.brouwer@collabora.com>

drm/tyr: add a kernel buffer object

This commit introduces a buffer object type (KernelBo) for internal driver
allocations managed by the kernel. It wraps a GEM shmem object and automatically
handles GPU virtual address space mapping during creation and unmapping on drop.

> diff --git a/drivers/gpu/drm/tyr/gem.rs b/drivers/gpu/drm/tyr/gem.rs
> index c28be61a01bb2..69e1c75e59a55 100644
> --- a/drivers/gpu/drm/tyr/gem.rs
> +++ b/drivers/gpu/drm/tyr/gem.rs

[ ... ]

> +impl Drop for KernelBo<'_> {
> +    fn drop(&mut self) {
> +        let va = self.va_range.start;
> +        let size = self.va_range.end - self.va_range.start;
> +
> +        if let Err(e) = self.vm.unmap_range(va, size) {

[Severity: Medium]
Does this leak the GEM buffer object if unmap_range() fails?

If unmap_range() encounters an error (such as a kmalloc failure due to
memory pressure when preallocating GPUVA objects to handle a mapping split),
it aborts the unmap operation. 

Because the error is caught and ignored here, the drm_gpuvm will retain its
reference to the GEM object indefinitely, leaking it along with its
physical pages.

> +            // If unmap_range fails, it is still safe to drop the
> +            // KernelBo and its ARef to the GEM buffer object because
> +            // GPUVM also holds a reference to the GEM buffer object.
> +            // The physical pages won't be freed or reallocated.
> +            dev_err!(
> +                self.vm.dev(),
> +                "Failed to unmap KernelBo range {:#x}..{:#x}: {:?}",
> +                self.va_range.start,
> +                self.va_range.end,
> +                e
> +            );
> +        }
> +    }
> +}

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Sashiko AI review · https://sashiko.dev/#/patchset/20260728-fw-boot-b4-v10-0-9187aefa3f2f@collabora.com?part=5