pcpu_next_md_free_region(9)

💖 pcpu_next_md_free_region(9) 💖

okay so this entire page is from the Kernel API Manual, and it’s here to explain one very specific little helper. It’s giving “deep in the kernel group chat” energy, and honestly? iconic.

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✨ NAME ✨

pcpu_next_md_free_region — finds the next hint free area 🎯

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🎀 SYNOPSIS 🎀

void pcpu_next_md_free_region (struct pcpu_chunk *chunk , int *bit_off ,
       int *bits );

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🧚 ARGUMENTS 🧚

• chunk — chunk of interest, bestie. That’s the chunk we’re looking at.
• bit_off — chunk offset.
• bits — size of free area.

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💅 DESCRIPTION 💅

So this is a helper function for pcpu_for_each_md_free_region. No cap.

It checks block->contig_hint and performs aggregation across blocks to find the next hint. The way it does that is very “main character energy”: it modifies bit_off and bits in-place to be consumed in the loop. ✨

In-place updates are the vibe here — bit_off and bits get changed right where they are, and that’s exactly what the loop expects. 💖

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🦋 SEE ALSO 🦋

Kernel file: ./mm/percpu.c — plus the whole related squad below:

• pcpu_addr_in_chunk(9)
• pcpu_check_block_hint(9)
• pcpu_next_fit_region(9)
• pcpu_mem_zalloc(9)
• pcpu_mem_free(9)
• pcpu_chunk_relocate(9)
• pcpu_block_update(9)
• pcpu_chunk_refresh_hint(9)
• pcpu_block_refresh_hint(9)
• pcpu_block_update_hint_alloc(9)
• pcpu_block_update_hint_free(9)
• pcpu_is_populated(9)
• pcpu_find_block_fit(9)
• pcpu_alloc_area(9)
• pcpu_free_area(9)
• pcpu_alloc_first_chunk(9)
• pcpu_chunk_populated(9)
• pcpu_chunk_depopulated(9)
• pcpu_chunk_addr_search(9)
• pcpu_alloc(9)
• pcpu_balance_free(9)
• pcpu_balance_populated(9)
• pcpu_reclaim_populated(9)
• pcpu_balance_workfn(9)
• free_percpu(9)
• is_kernel_percpu_address(9)
• per_cpu_ptr_to_phys(9)
• pcpu_alloc_alloc_info(9)
• pcpu_free_alloc_info(9)
• pcpu_dump_alloc_info(9)
• pcpu_setup_first_chunk(9)
• pcpu_build_alloc_info(9)
• pcpu_embed_first_chunk(9)
• pcpu_page_first_chunk(9)

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Source/version: ./mm · Date: October 2026 · Page: pcpu_next_md_free_region(9) — that’s the footer, bestie, and we ate 💅💖