sparse_add_section(9)

💖 NAME 💖

okay bestie, welcome to sparse_add_section(9) from the Kernel API Manual — she adds a memory section, or populates one that’s already there. lowkey iconic. ✨

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✨ SYNOPSIS ✨

int sparse_add_section (int nid , unsigned long start_pfn , unsigned
       long nr_pages , struct vmem_altmap *altmap , struct dev_pagemap *pgmap
       );

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🎀 ARGUMENTS 🎀

• nid — the node to add the section on. like, which node bestie 💅
• start_pfn — start pfn of the memory range. periodt.
• nr_pages — number of pfns to add in the section.
• altmap — alternate pfns to allocate the memmap backing store.
• pgmap — alternate compound page geometry for devmap mappings.

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🦋 DESCRIPTION 🦋

so this one is only intended for hotplug. no cap. 🫶

note bestie: only VMEMMAP supports sub-section aligned hotplug, and the proper alignment and size are gated by check_pfn_span. that part is literally the vibe check. 💀

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🔥 RETURN 🔥

• 0 — on success. slay. 💖
• -EEXIST — section has been present. like, it’s already there, bestie. 🙈
• -ENOMEM — out of memory. 😭

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🌈 SEE ALSO 🌈

kernel file ./mm/sparse-vmemmap.c — go peek, iykyk. 🦋

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mwah 💋 — source/version: ./mm, date: October 2026, page: sparse_add_section(9). that’s the cute little sign-off, bestie 🎀✨