folio_add_new_anon_rmap(9)

📦 version 7.3.1, in nixpkgs unstable

✨ folio_add_new_anon_rmap ✨

okay bestie, so this one is a kernel API manual page, like from the Kernel API Manual bestie, and we're literally about to get into it 💅

🌸 NAME 🌸

folio_add_new_anon_rmap — add mapping to a new anonymous folio. periodt.

🦋 SYNOPSIS 🦋

void folio_add_new_anon_rmap (struct folio *folio , struct
       vm_area_struct *vma , unsigned long address , rmap_t flags );

🎀 ARGUMENTS 🎀

  • folio — the folio we're adding the mapping to, bestie. that's the main character right there.
  • vma — the vm area in which the mapping is added. it's giving "where the vibe lives".
  • address — the user virtual address mapped. literally the address, no cap.
  • flags — the rmap flags. yes queen, flags.

💖 DESCRIPTION 💖

so this is like folio_add_anon_rmap_*() but bestie… it must only be called on new folios. i cannot stress this enough like fr fr. this means the inc-and-test can be bypassed — slay, we skip that step.

the folio doesn't necessarily need to be locked while it's exclusive, unless two threads map it concurrently (messy, avoid). however — and this is the important part — the folio must be locked if it's shared. like, do not come for me if you skip this, i warned you 😭💀

if the folio is pmd-mappable, it is accounted as a THP. that's it, that's the tea 🍓.

lowkey a vibe check: new folios only, lock it if shared, no exceptions 🫶

👑 SEE ALSO 👑

kernel file ./mm/rmap.c:

and that's the whole page, bestie — no crumbs left behind 💅✨ this iconic lil manual page lives in ./mm, dated October 2026, and it's literally called folio_add_new_anon_rmap(9). go off, kernel queen 👑💜

📦 where this page comes from