unmap_mapping_range(9)

💅 unmap_mapping_range

okay bestie, welcome to the unmap_mapping_range page from the Kernel API Manual — yes, that's the manual name, we're fancy like that 🎀

✨ NAME ✨

unmap_mapping_range — literally unmap the portion of all mmaps in the specified address_space that corresponds to the specified byte range in the underlying file. that's it, that's the whole vibe 💅

🌸 SYNOPSIS 🌸

void unmap_mapping_range (struct address_space *mapping , loff_t const
holebegin , loff_t const holelen , int even_cows );

no cap, that's the exact signature, copy it exactly please 🙏

🦋 ARGUMENTS 🦋

• mapping — the address space that's holding the mmaps you want unmapped. it's giving "which friend group are we removing from the chat" energy 🫶
• holebegin — the byte in the first page to unmap, measured relative to the start of the underlying file. heads up: this gets rounded down to a PAGE_SIZE boundary ✨ and note that this is different from truncate_pagecache, which must keep the partial page. we, in contrast, must get rid of partial pages. no partial pages allowed, periodt 💀
• holelen — the size of the prospective hole, in bytes. this one gets rounded up to a PAGE_SIZE boundary. and a holelen of zero truncates to the end of the file. zero means "all the way, bestie" 🔥
• even_cows — set to 1 when you're truncating a file, so you unmap even private COWed pages; but set it to 0 when you're invalidating pagecache, because then you don't throw away private data. pick wisely, this is the main character decision of the whole call 👑

👑 SEE ALSO 👑

this is the whole Kernel file ./mm/memory.c crew, and they're all here, every single one, no gatekeeping 🧚:

free_pgd_range(9), free_pgtables(9), __vm_normal_page(9), vm_normal_page(9), vm_normal_folio(9), vm_normal_page_pmd(9), vm_normal_folio_pmd(9), vm_normal_page_pud(9), restore_exclusive_pte(9), cond_install_uffd_wp_ptes(9), zap_vma_for_reaping(9), unmap_vmas(9), zap_vma_range_batched(9), zap_vma_range(9), zap_special_vma_range(9), vm_insert_pages(9), vm_insert_page(9), vm_map_pages(9), vm_map_pages_zero(9), vmf_insert_pfn_prot(9), vmf_insert_pfn(9), remap_pfn_range(9), vm_iomap_memory(9), __vmf_anon_prepare(9), finish_mkwrite_fault(9), unmap_mapping_folio(9), unmap_mapping_pages(9), set_pte_range(9), finish_fault(9), mm_account_fault(9), follow_pfnmap_start(9), follow_pfnmap_end(9), generic_access_phys(9), access_remote_vm(9), copy_remote_vm_str(9), folio_zero_user(9)

like, that is a lot of friends and we are not skipping any of them. iykyk 🌈

💖 okay that's the whole page, you ate that. this one came out of ./mm in October 2026, so go forth and unmap responsibly, bestie — mwah 🎀🦋💜