Re: [PATCH V19 13/15] drm/xe: Expose bad VRAM pages via debugfs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Incorrect PFN calculation and page size reporting on architectures with non-4KB CPU pages.
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commit 582114b5c95fb63375e25846ac38204e4e81d526
Author: Tejas Upadhyay <tejas.upadhyay@intel.com>

drm/xe: Expose bad VRAM pages via debugfs

This commit adds a debugfs file vram_bad_pages that displays offlined
and queued VRAM pages across all tiles.

> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index 286c866f1d581..456ea78a31e2a 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
[ ... ]
> @@ -845,3 +846,61 @@ int xe_ttm_vram_handle_addr_fault(struct xe_device *xe, u64 addr)
> +static int vram_bad_pages_show(struct seq_file *m, void *unused)
> +{
[ ... ]
> +		list_for_each_entry_rcu(pos, &mgr->offlined_pages, offlined_link) {
> +			u64 pfn;
> +
> +			pfn = (pos->addr + vr->dpa_base) >> PAGE_SHIFT;
> +			seq_printf(m, "0x%016llx : 0x%016lx : R\n", pfn, PAGE_SIZE);
> +		}
> +
> +		list_for_each_entry_rcu(pos, &mgr->queued_pages, queued_link) {
> +			u64 pfn;
> +
> +			pfn = (pos->addr + vr->dpa_base) >> PAGE_SHIFT;
> +			seq_printf(m, "0x%016llx : 0x%016lx : %c\n",
> +				   pfn, PAGE_SIZE, pos->status ? 'F' : 'P');
> +		}

[Severity: Medium]
Will this calculate and report incorrect page frame numbers (PFN) and page
sizes on architectures with non-4KB CPU pages?

On systems where CPU page size is greater than 4KB (such as ARM64 with 64KB
pages), using PAGE_SHIFT and PAGE_SIZE in vram_bad_pages_show() will truncate
the 4KB-aligned address bits and display the CPU page size instead of the
intended GPU page size, breaking diagnostic statistics.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260831064942.315720-17-tejas.upadhyay@intel.com?part=13