alloc_rtree_node(9)

👑 alloc_rtree_node — Kernel API Manual vibes ✨

okay so bestie, you're in the Kernel API Manual and today's main character is alloc_rtree_node(9). buckle up 🎀

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🌸 NAME 🌸

alloc_rtree_node — allocate a brand new node and, like, add it to the radix tree. that's the whole job. she's employed 💅

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✨ SYNOPSIS ✨

struct rtree_node * alloc_rtree_node (gfp_t gfp_mask , int safe_needed ,
struct chain_allocator *ca , struct list_head *list );

literally just call her with those four things and she'll hand you back a struct rtree_node *, no cap 🫶

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🦋 ARGUMENTS 🦋

• gfp_mask — the GFP mask for the allocation. it's giving "how hard should I try to get memory" energy.
• safe_needed — get pages that haven't been used before hibernation. restore only, so don't be weird about it 😭 this one's niche.
• ca — a pointer to a linked list of pages (yep, a "chain") that we allocate from. it's giving actual chain, not the cute necklace kind 🔗
• list — the Radix Tree node to add. she gets appended, periodt.

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💖 DESCRIPTION 💖

so what does she actually do? bestie. she's the one who allocates inner nodes and the leave nodes of the radix tree — both, iconic versatility 👑

and then, because she's not just pretty, she also adds the node to the corresponding linked list that got passed in through the *list parameter. multitasking queen fr fr 🌈

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🔥 SEE ALSO 🔥

kernel file ./kernel/power/snapshot.c — that's where the whole friend group lives:

• get_image_page(9)
• free_image_page(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)
• minimum_image_size(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)

like, the entire group chat. go read them, iykyk 💜

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ngl if you're poking at hibernation/snapshot code, you're in ./kernel/power territory — that's the address on the mailbox, bestie 🏡

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so yeah, that's the whole page 🍓 shoutout to the ./kernel/power source, dated October 2026, for being the origin of all this. mwah, love u, bye 😭💖