wp_shared_mapping_range(9)

💅 wp_shared_mapping_range(9) 💅

ok so this is a page from the Kernel API Manual (section 9, kernel devs only, iykyk) and honestly? it's giving "small function, big responsibilities." let's get into it ✨

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🌸 NAME 🌸

wp_shared_mapping_range — write-protect all the ptes in an address space range, bestie. every single one. no crumbs left behind 💖

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🦋 SYNOPSIS 🦋

unsigned long wp_shared_mapping_range (struct address_space *mapping ,
pgoff_t first_index , pgoff_t nr );

like look at that signature. so clean. so intentional. and yes it returns an unsigned long, keep that in your notes 📝

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🎀 ARGUMENTS 🎀

• mapping — the address_space we want to write protect. this is the main character of the whole operation, fr fr 👑
• first_index — the first page offset in the range. where the vibes begin ✨
• nr — number of incremental page offsets to cover. so like, how far we're walking from first_index, one page offset at a time 🌈

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😭 NOTE 😭

ok important heads-up, bestie. this function currently skips transhuge page-table entries, because it's intended for dirty-tracking on the PTE level. that's the whole design rn, no cap.

but 👀 — it will warn on encountering transhuge write-enabled entries. and lowkey it can easily be extended to handle them as well, so it's not a permanent situation, it's just the current vibe check. so if you see that warning, that's why 💀

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🫶 RETURN 🫶

it returns the number of ptes actually write-protected. and here's the lil gotcha that trips people up: already write-protected ptes are not counted. so don't @ me when your count is lower than you expected — that's literally the design 🙈

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🧚 SEE ALSO 🧚

• Kernel file ./mm/mapping_dirty_helpers.c
• struct wp_walk(9)
• wp_pte(9)
• struct clean_walk(9)
• clean_record_pte(9)
• clean_record_shared_mapping_range(9)

go read the whole little family, they're all in on the same dirty-tracking plot 🍓

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⭐ sign-off ⭐

this page lives in ./mm from October 2026 — go off, kernel docs 💜 slay, stay write-protected, and remember: skipping transhuge entries is a feature, not a bug (for now) 💅✨