Re: [PATCH V18 05/14] drm/xe: Guard teardown paths against purged BOs

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Medium] Missing xe_bo_is_purged() guard in PSMI teardown path causes xe_assert warnings on purged BOs.
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commit b5b060f35b87d3363b29c5356982c12efa65fab5
Author: Tejas Upadhyay <tejas.upadhyay@intel.com>

drm/xe: Guard teardown paths against purged BOs

This commit adds guards to prevent unpinning or mapping buffer objects that
have already been purged by VRAM page offlining in multiple teardown paths.

> diff --git a/drivers/gpu/drm/xe/xe_bo.h b/drivers/gpu/drm/xe/xe_bo.h
> index eede678ad303a..dfcd0e57073be 100644
> --- a/drivers/gpu/drm/xe/xe_bo.h
> +++ b/drivers/gpu/drm/xe/xe_bo.h
> @@ -364,7 +364,8 @@ static inline void xe_bo_unpin_map_no_vm(struct xe_bo *bo)
>  {
>  	if (likely(bo)) {
>  		xe_bo_lock(bo, false);
> -		xe_bo_unpin(bo);
> +		if (!xe_bo_is_purged(bo))
> +			xe_bo_unpin(bo);
>  		xe_bo_unlock(bo);

[Severity: Medium]
Does the PSMI teardown path in psmi_free_object() also need this guard?

Looking at drivers/gpu/drm/xe/xe_psmi.c, psmi_free_object() unpins the
capture BO without checking if it was purged:

drivers/gpu/drm/xe/xe_psmi.c:psmi_free_object() {
        ...
        xe_bo_lock(bo, NULL);
        xe_bo_unpin(bo);
        xe_bo_unlock(bo);
        ...
}

If the PSMI capture buffer is allocated, it is pinned in VRAM and tagged with
the XE_BO_FLAG_PINNED_LATE_RESTORE flag. If a VRAM page offline fault occurs,
xe_ttm_vram_reserve_page_at_addr() will successfully purge and unpin the BO
because the LATE_RESTORE flag explicitly bypasses the system reset check.

Later, when PSMI is disabled or resized, psmi_cleanup() calls
psmi_free_object(), which directly calls xe_bo_unpin() without checking
xe_bo_is_purged(). Calling xe_bo_unpin() on a BO with a 0 pin count triggers
xe_assert(xe, xe_bo_is_pinned(bo)) in Xe and a WARN_ON_ONCE in the TTM core.

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Sashiko AI review · https://sashiko.dev/#/patchset/20260826135136.204044-16-tejas.upadhyay@intel.com?part=5