kunmap(9)

💅 kunmap — kernel API manual, but make it make sense 💅

okay so bestie, welcome to kunmap(9) — straight out of the Kernel API Manual, and honestly? she's a supporting character who does her job flawlessly and never asks for credit. we stan a humble icon 🫶

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✨ NAME ✨

kunmap — the girl whose whole job is unmapping the virtual address that was mapped by kmap(). that's it. that's the gig. reverse uno card energy 🔄💖

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🌸 SYNOPSIS 🌸

void kunmap (const struct page *page );

like. she takes one argument. void return. no drama, no cap. 💅

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🎀 ARGUMENTS 🎀

• page — Pointer to the page which was mapped by kmap. that's the exact same struct page * you handed to kmap earlier, bestie. don't get cute and pass a different one 🙈

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🦋 DESCRIPTION 🦋

so the tea is: kunmap is the counterpart to kmap. kmap maps, kunmap unmaps. they're a matched set, a duo, the main character and her ride-or-die. 👑

and here's the part that lowkey slays: she's a NOOP (that's "no operation", for the uninitiated 💀) when CONFIG_HIGHMEM=n. also a NOOP for mappings of pages in the low memory area. so sometimes she literally does nothing and that's correct behaviour, not laziness. honestly? queen. she knows when not to act. 🌈✨

fr fr though — this is not a "maybe it did something" situation. it is defined to be a no-op in those cases. no guessing, no vibes-based kernel debugging. 🧚

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🔥 SEE ALSO 🔥

Kernel file ./include/linux/highmem.h — go read her whole friend group, they're all icons:

• kmap(9)
• kmap_to_page(9)
• kmap_flush_unused(9)
• kmap_local_page(9)
• kmap_local_folio(9)
• kmap_atomic(9)
• clear_user_page(9)
• clear_user_pages(9)
• clear_user_highpage(9)
• clear_user_highpages(9)
• vma_alloc_zeroed_movable_folio(9)
• memcpy_from_folio(9)
• memcpy_to_folio(9)
• folio_zero_tail(9)
• folio_fill_tail(9)
• memcpy_from_file_folio(9)
• folio_zero_segments(9)
• folio_zero_segment(9)
• folio_zero_range(9)
• folio_release_kmap(9)

like, that's a whole squad. group chat is poppin' off. 🍓💜

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okay that's the whole page, bestie — this cutie lives in ./include/linux, dated October 2026, and that's the vibe check complete. go unmap something responsibly. mwah 💋✨