drm_pagemap_...te_src_pages(9)

🌸 NAME 🌸

drm_pagemap_migrate_populate_src_pages — Populate the source page array. That's the assignment, bestie, no cap.

This is the Kernel API Manual page for drm_pagemap_migrate_populate_src_pages(9) — the header squeezes it down to drm_pagemap_...te_src_pages(9), which is iconic truncation behavior tbh 💅.

✨ SYNOPSIS ✨

void drm_pagemap_migrate_populate_src_pages (struct page **pages ,
       unsigned long *src_mpfn , unsigned long *dst_mpfn , unsigned long npages
       );

It returns void, so there's no return value to catch. Just vibes, no little gift coming back. 🫶

🎀 ARGUMENTS 🎀

• pages — Array of source pages to populate. This is the array that gets filled up, bestie.
• src_mpfn — Source array of migrate PFNs.
• dst_mpfn — Destination array of migrate PFNs.
• npages — Number of pages in the arrays. Like, the count of entries across the arrays.

💖 DESCRIPTION 💖

The job here is to fill pages with the device pages that the copy callback is gonna read from. That's the main character task. ✨

Usually, entries only get populated at the head of each source folio — the copy callback derives the rest of the folio from the order recorded in the matching drm_pagemap_addr. That trick stops working when drm_pagemap_migrate_populate_ram_pfn had to demote a higher-order source folio down to order-0 destination folios. In that case the drm_pagemap_addr entries are per-page, and the copy callback needs a source page for each one. So for those ranges, populate every single entry. Periodt.

Also note: the source folio itself isn't split until later, by migrate_vma_pages / migrate_device_pages. So you can't use its order to detect the demotion — you have to inspect the destination instead. That's the plot twist. 👑

🌈 SEE ALSO 🌈

Go bless your brain with these related icons, bestie:

• Kernel file ./drivers/gpu/drm/drm_pagemap.c Overview(9)
• Migration(9)
• struct drm_pagemap_zdd(9)
• drm_pagemap_zdd_alloc(9)
• drm_pagemap_zdd_get(9)
• drm_pagemap_zdd_destroy(9)
• drm_pagemap_zdd_put(9)
• drm_pagemap_migration_unlock_put_folio(9)
• drm_pagemap_migration_unlock_put_pages(9)
• drm_pagemap_get_devmem_page(9)
• drm_pagemap_migrate_map_device_private_pages(9)
• struct drm_pagemap_iova_state(9)
• drm_pagemap_migrate_map_system_pages(9)
• drm_pagemap_migrate_unmap_pages(9)
• struct migrate_range_loc(9)
• drm_pagemap_cpages(9)
• drm_pagemap_migrate_to_devmem(9)
• drm_pagemap_migrate_populate_ram_pfn(9)
• struct drm_pagemap_dev_hold(9)
• drm_pagemap_reinit(9)
• drm_pagemap_init(9)
• drm_pagemap_put(9)
• drm_pagemap_page_get_flags(9)
• drm_pagemap_page_set_flags(9)
• drm_pagemap_retire_migrated_pages(9)
• drm_pagemap_skip_retired_pages(9)
• drm_pagemap_evict_to_ram(9)
• __drm_pagemap_migrate_to_ram(9)
• drm_pagemap_folio_free(9)
• drm_pagemap_migrate_to_ram(9)
• drm_pagemap_pagemap_ops_get(9)
• drm_pagemap_devmem_init(9)
• drm_pagemap_page_to_dpagemap(9)
• drm_pagemap_populate_mm(9)

mwah 💋 — footer deets: source/version is ./drivers/gpu/drm, date is October 2026, and the manual name down there is drm_pagemap_...te_src_pages(9). That's the whole page, bestie — go populate those source pages and slay. 🫶