Re: [PATCH V15 08/14] drm/xe/vram: Add page offline data structures and lifecycle

["Ghimiray, Himal Prasad" <himal.prasad.ghimiray@intel.com>]

On 11-08-2026 18:10, Tejas Upadhyay wrote:
> Add xe_ttm_vram_offline_resource to track individual offlined VRAM
> pages, and extend xe_ttm_vram_mgr with offlined_pages/queued_pages
> lists and their counters.
> 
> Initialize the lists in __xe_ttm_vram_mgr_init() and add
> xe_ttm_vram_free_bad_pages() to release all tracked pages during
> xe_ttm_vram_mgr_fini() teardown.
> 
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr.c       | 24 ++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h | 26 ++++++++++++++++++++++
>   2 files changed, 50 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> index 49eeec90a470..2813ae68325e 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr.c
> @@ -300,6 +300,24 @@ static const struct ttm_resource_manager_func xe_ttm_vram_mgr_func = {
>   	.debug	= xe_ttm_vram_mgr_debug
>   };
>   
> +static void xe_ttm_vram_free_bad_pages(struct drm_device *dev, struct xe_ttm_vram_mgr *mgr)
> +{

Don't see dev being used ?

> +	struct xe_ttm_vram_offline_resource *pos, *n;
> +
> +	list_for_each_entry_safe(pos, n, &mgr->offlined_pages, offlined_link) {
> +		xe_ttm_vram_buddy_free(mgr, &pos->blocks, pos->used_visible_size);
> +		list_del(&pos->offlined_link);
> +		--mgr->n_offlined_pages;
> +		kfree(pos);
> +	}

This can be racy, better to use
list_del_rcu() + kfree_rcu()

> +	list_for_each_entry_safe(pos, n, &mgr->queued_pages, queued_link) {
> +		xe_ttm_vram_buddy_free(mgr, &pos->blocks, 0);

Nit: pos->used_visible_size is always 0, hardcoding is Ok. comment it ?

> +		list_del(&pos->queued_link);
> +		--mgr->n_queued_pages;
> +		kfree(pos);
> +	}
> +}
> +
>   static void xe_ttm_vram_mgr_fini(struct drm_device *dev, void *arg)
>   {
>   	struct xe_device *xe = to_xe_device(dev);
> @@ -311,6 +329,10 @@ static void xe_ttm_vram_mgr_fini(struct drm_device *dev, void *arg)
>   	if (ttm_resource_manager_evict_all(&xe->ttm, man))
>   		return;
>


potential leak here due to early return ?

> +	mutex_lock(&mgr->lock);
> +	xe_ttm_vram_free_bad_pages(dev, mgr);
> +	mutex_unlock(&mgr->lock);
> +
>   	WARN_ON_ONCE(mgr->visible_avail != mgr->visible_size);
>   
>   	gpu_buddy_fini(&mgr->mm);
> @@ -338,6 +360,8 @@ int __xe_ttm_vram_mgr_init(struct xe_device *xe, struct xe_ttm_vram_mgr *mgr,
>   	err = drmm_mutex_init(&xe->drm, &mgr->lock);
>   	if (err)
>   		return err;
> +	INIT_LIST_HEAD(&mgr->offlined_pages);
> +	INIT_LIST_HEAD(&mgr->queued_pages);
>   	mgr->default_page_size = default_page_size;
>   	mgr->visible_size = io_size;
>   	mgr->visible_avail = io_size;
> diff --git a/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h b/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> index 9106da056b49..bdfdf6ec1218 100644
> --- a/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> +++ b/drivers/gpu/drm/xe/xe_ttm_vram_mgr_types.h
> @@ -19,6 +19,14 @@ struct xe_ttm_vram_mgr {
>   	struct ttm_resource_manager manager;
>   	/** @mm: DRM buddy allocator which manages the VRAM */
>   	struct gpu_buddy mm;
> +	/** @offlined_pages: List of offlined pages */
> +	struct list_head offlined_pages;
> +	/** @n_offlined_pages: Number of offlined pages */
> +	u16 n_offlined_pages;
> +	/** @queued_pages: List of queued pages */
> +	struct list_head queued_pages;
> +	/** @n_queued_pages: Number of queued pages */
> +	u16 n_queued_pages;
>   	/** @visible_size: Proped size of the CPU visible portion */
>   	u64 visible_size;
>   	/** @visible_avail: CPU visible portion still unallocated */
> @@ -45,4 +53,22 @@ struct xe_ttm_vram_mgr_resource {
>   	unsigned long flags;
>   };
>   
> +/**
> + * struct xe_ttm_vram_offline_resource - Tracks a single offlined VRAM page
> + */
> +struct xe_ttm_vram_offline_resource {
> +	/** @offlined_link: Link into mgr->offlined_pages */
> +	struct list_head offlined_link;
> +	/** @queued_link: Link into mgr->queued_pages */
> +	struct list_head queued_link;
> +	/** @blocks: Buddy blocks reserved for this page */
> +	struct list_head blocks;
> +	/** @used_visible_size: CPU-visible bytes consumed */
> +	u64 used_visible_size;
> +	/** @addr: Faulty DPA reported by HW */
> +	u64 addr;
> +	/** @status: Reservation status (0=pending, 1=fail) */
> +	bool status;
> +};
> +
>   #endif