gmap_helper..._cow_sharing(9)

🎀 NAME 🎀

okay so this is from the Kernel API Manual, and the function is gmap_helper_disable_cow_sharing — it disables all COW sharing. bestie, it’s giving “shut it down” energy 💅

✨ SYNOPSIS ✨

int gmap_helper_disable_cow_sharing (void );

🫶 ARGUMENTS 🫶

• void — no arguments. literally none. not a single one 😌

💖 DESCRIPTION 💖

This one disables most COW-sharing of memory pages for the whole process. like, the entire process, no cap. it does it in two steps:

1. Disables KSM and unmerges/unshares any KSM pages. bye 👋
2. Disallows shared zeropages and unshares any zerpages that are mapped. (yes, zerpages — that’s the page’s spelling, not me 😭)

Also, just so you know: we currently don’t bother with COW-shared pages that are shared with parent/child processes due to fork. that’s the note 🫡

🌈 SEE ALSO 🌈

• Kernel file ./arch/s390/mm/gmap_helpers.c
• try_get_locked_pte(9)
• gmap_helper_zap_one_page(9)
• gmap_helper_discard(9)
• gmap_helper_try_set_pte_unused(9)

go read these too, iykyk 👑

mwah 💋 — from ./arch/s390/mm, October 2026. periodt. 🎀