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drm/pagemap: Correct cpages calculation for migrate_vma_setup

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cpages returned from migrate_vma_setup represents the total number of
individual pages found, not the number of 4K pages. The math in
drm_pagemap_migrate_to_devmem for npages is based on the number of 4K
pages, so cpages != npages can fail even if the entire memory range is
found in migrate_vma_setup (e.g., when a single 2M page is found).
Add drm_pagemap_cpages, which converts cpages to the number of 4K pages
found.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: linux-mm@kvack.org
Reviewed-by: Francois Dugast <francois.dugast@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Link: https://patch.msgid.link/20260312192126.2024853-4-francois.dugast@intel.com
This commit is contained in:
Matthew Brost 2026-03-12 20:20:13 +01:00
parent 2e03c0c5c5
commit 139ab31aea
1 changed files with 37 additions and 1 deletions
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38
drivers/gpu/drm/drm_pagemap.c
View File

@ -452,6 +452,41 @@ static int drm_pagemap_migrate_range(struct drm_pagemap_devmem *devmem,
return ret;
}
/**
* drm_pagemap_cpages() - Count collected pages
* @migrate_pfn: Array of migrate_pfn entries to account
* @npages: Number of entries in @migrate_pfn
*
* Compute the total number of minimum-sized pages represented by the
* collected entries in @migrate_pfn. The total is derived from the
* order encoded in each entry.
*
* Return: Total number of minimum-sized pages.
*/
static int drm_pagemap_cpages(unsigned long *migrate_pfn, unsigned long npages)
{
unsigned long i, cpages = 0;
for (i = 0; i < npages;) {
struct page *page = migrate_pfn_to_page(migrate_pfn[i]);
struct folio *folio;
unsigned int order = 0;
if (page) {
folio = page_folio(page);
order = folio_order(folio);
cpages += NR_PAGES(order);
} else if (migrate_pfn[i] & MIGRATE_PFN_COMPOUND) {
order = HPAGE_PMD_ORDER;
cpages += NR_PAGES(order);
}
i += NR_PAGES(order);
}
return cpages;
}
/**
* drm_pagemap_migrate_to_devmem() - Migrate a struct mm_struct range to device memory
* @devmem_allocation: The device memory allocation to migrate to.
@ -554,7 +589,8 @@ int drm_pagemap_migrate_to_devmem(struct drm_pagemap_devmem *devmem_allocation,
goto err_free;
}
if (migrate.cpages != npages) {
if (migrate.cpages != npages &&
drm_pagemap_cpages(migrate.src, npages) != npages) {
/*
* Some pages to migrate. But we want to migrate all or
* nothing. Raced or unknown device pages.