linux-kernel - Re: [PATCH v3 13/13] mm: Remove device private pages from the physical address space

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Message-ID: <413d265f-9ffc-499b-8dbc-26f92bdff6d8@nvidia.com>
Date: Tue, 27 Jan 2026 11:29:30 +1100
From: Jordan Niethe <jniethe@...dia.com>
To: linux-mm@...ck.org
Cc: balbirs@...dia.com, matthew.brost@...el.com, akpm@...ux-foundation.org,
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
 david@...hat.com, ziy@...dia.com, apopple@...dia.com,
 lorenzo.stoakes@...cle.com, lyude@...hat.com, dakr@...nel.org,
 airlied@...il.com, simona@...ll.ch, rcampbell@...dia.com,
 mpenttil@...hat.com, jgg@...dia.com, willy@...radead.org,
 linuxppc-dev@...ts.ozlabs.org, intel-xe@...ts.freedesktop.org, jgg@...pe.ca,
 Felix.Kuehling@....com, jhubbard@...dia.com
Subject: Re: [PATCH v3 13/13] mm: Remove device private pages from the
 physical address space

Hi,

On 23/1/26 17:23, Jordan Niethe wrote:

> diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
> index a8aad9e0b1fb..ac3da24b2aac 100644
> --- a/drivers/gpu/drm/xe/xe_svm.c
> +++ b/drivers/gpu/drm/xe/xe_svm.c
> @@ -452,7 +452,7 @@ static u64 xe_page_to_dpa(struct page *page)
>   	struct xe_pagemap *xpagemap = xe_page_to_pagemap(page);
>   	struct xe_vram_region *vr = xe_pagemap_to_vr(xpagemap);
>   	u64 hpa_base = xpagemap->hpa_base;
> -	u64 pfn = page_to_pfn(page);
> +	u64 pfn = device_private_page_to_offset(page);
>   	u64 offset;
>   	u64 dpa;
>   
> @@ -1700,8 +1700,6 @@ static void xe_pagemap_destroy_work(struct work_struct *work)
>   	 */
>   	if (drm_dev_enter(drm, &idx)) {
>   		devm_memunmap_pages(drm->dev, pagemap);
> -		devm_release_mem_region(drm->dev, pagemap->range.start,
> -					pagemap->range.end - pagemap->range.start + 1);
>   		drm_dev_exit(idx);
>   	}

There's some new failures on the intel-xe CI run: https://patchwork.freedesktop.org/series/159738/#rev5
Looks like the issue is a missing update to call devm_memunmap_device_private_pagemap():

diff --git a/drivers/gpu/drm/xe/xe_svm.c b/drivers/gpu/drm/xe/xe_svm.c
index ac3da24b2aac..aadc73b6f951 100644
--- a/drivers/gpu/drm/xe/xe_svm.c
+++ b/drivers/gpu/drm/xe/xe_svm.c
@@ -1699,7 +1699,7 @@ static void xe_pagemap_destroy_work(struct work_struct *work)
          * will do shortly.
          */
         if (drm_dev_enter(drm, &idx)) {
-               devm_memunmap_pages(drm->dev, pagemap);
+               devm_memunmap_device_private_pagemap(drm->dev, pagemap);
                 drm_dev_exit(idx);
         }
  


Thanks,
Jordan.

>   
> @@ -1745,8 +1743,6 @@ static struct xe_pagemap *xe_pagemap_create(struct xe_device *xe, struct xe_vram
>   	struct xe_pagemap *xpagemap;
>   	struct dev_pagemap *pagemap;
>   	struct drm_pagemap *dpagemap;
> -	struct resource *res;
> -	void *addr;
>   	int err;
>   
>   	xpagemap = kzalloc(sizeof(*xpagemap), GFP_KERNEL);
> @@ -1763,36 +1759,24 @@ static struct xe_pagemap *xe_pagemap_create(struct xe_device *xe, struct xe_vram
>   	if (err)
>   		goto out_no_dpagemap;
>   
> -	res = devm_request_free_mem_region(dev, &iomem_resource,
> -					   vr->usable_size);
> -	if (IS_ERR(res)) {
> -		err = PTR_ERR(res);
> -		goto out_err;
> -	}
> -
>   	err = drm_pagemap_acquire_owner(&xpagemap->peer, &xe_owner_list,
>   					xe_has_interconnect);
>   	if (err)
> -		goto out_no_owner;
> +		goto out_err;
>   
>   	pagemap->type = MEMORY_DEVICE_PRIVATE;
> -	pagemap->range.start = res->start;
> -	pagemap->range.end = res->end;
>   	pagemap->nr_range = 1;
> +	pagemap->nr_pages = vr->usable_size / PAGE_SIZE;
>   	pagemap->owner = xpagemap->peer.owner;
>   	pagemap->ops = drm_pagemap_pagemap_ops_get();
> -	addr = devm_memremap_pages(dev, pagemap);
> -	if (IS_ERR(addr)) {
> -		err = PTR_ERR(addr);
> +	err = devm_memremap_device_private_pagemap(dev, pagemap);
> +	if (err)
>   		goto out_no_pages;
> -	}
> -	xpagemap->hpa_base = res->start;
> +	xpagemap->hpa_base = pagemap->range.start;
>   	return xpagemap;
>   
>   out_no_pages:
>   	drm_pagemap_release_owner(&xpagemap->peer);
> -out_no_owner:
> -	devm_release_mem_region(dev, res->start, res->end - res->start + 1);
>   out_err:
>   	drm_pagemap_put(dpagemap);
>   	return ERR_PTR(err);
> diff --git a/include/linux/hmm.h b/include/linux/hmm.h
> index d8756c341620..25bb4df298f7 100644