minimum_image_size(9)

🌸 NAME 🌸

okay so bestie, this page is from the Kernel API Manual, and the main character is minimum_image_size — literally here to estimate the minimum acceptable size of an image. 💅✨

✨ SYNOPSIS ✨

unsigned long minimum_image_size (unsigned long saveable );

🎀 ARGUMENTS 🎀

• saveable — the number of saveable pages in the system. that’s the whole input, bestie 🫶

💖 DESCRIPTION 💖

so the vibe is: we do not want to be out here attempting to free too much memory too hard. 😭 instead, this function estimates the minimum acceptable size of a hibernation image, and that estimate is used as the lower limit for preallocating memory. iconic, honestly.

we assume that the minimum image size should be proportional to

[number of saveable pages] - [number of pages that can be freed in theory]

where that second term is the sum of:

1. reclaimable slab pages
2. active anonymous pages
3. inactive anonymous pages
4. active file pages
5. inactive file pages

wait, let me say it cleaner: the second term is the sum of (1) reclaimable slab pages, (2) active and (3) inactive anonymous pages, (4) active and (5) inactive file pages. no cap. ✨

🦋 SEE ALSO 🦋

kernel file ./kernel/power/snapshot.c — plus these functions, all listed exactly:

• get_image_page(9)
• free_image_page(9)
• alloc_rtree_node(9)
• free_mem_extents(9)
• create_mem_extents(9)
• memory_bm_next_pfn(9)
• mark_nosave_pages(9)
• create_basic_memory_bitmaps(9)
• free_basic_memory_bitmaps(9)
• snapshot_additional_pages(9)
• count_free_highmem_pages(9)
• count_highmem_pages(9)
• count_data_pages(9)
• swsusp_free(9)
• preallocate_image_pages(9)
• free_unnecessary_pages(9)
• hibernate_preallocate_memory(9)
• pack_pfns(9)
• snapshot_read_next(9)
• unpack_orig_pfns(9)
• count_highmem_image_pages(9)
• prepare_highmem_image(9)
• copy_last_highmem_page(9)
• prepare_image(9)
• snapshot_write_next(9)
• restore_highmem(9)

and that’s the whole page, bestie. this one lives under ./kernel/power, dated October 2026, and yes it’s still minimum_image_size(9) — mwah 💋🎀