is_highmem(9)

🌸 NAME 🌸

Okay so bestie, welcome to the manual page for is_highmem(9) 💖. is_highmem is a helper function that quickly checks if a struct zone is a highmem zone or not. This is an attempt to keep references to ZONE_{DMA/NORMAL/HIGHMEM/etc} in general code to a minimum. Periodt. ✨

✨ SYNOPSIS ✨

Here's the signature, exactly as it is, because we do not mess with code in this house 🫶:

int is_highmem (const struct zone *zone );

🎀 ARGUMENTS 🎀

• zone — pointer to a struct zone variable. That's the whole argument, bestie.

🔥 RETURN 🔥

• 1 for a highmem zone.
• 0 otherwise.

🦋 SEE ALSO 🦋

The kernel file to peek at is ./include/linux/mmzone.h 👀. Also go hang out with:

• for_each_online_pgdat(9)
• for_each_zone(9)
• next_zones_zonelist(9)
• first_zones_zonelist(9)
• for_each_zone_zonelist_nodemask(9)
• for_each_zone_zonelist(9)
• pfn_valid(9)

Bye bestie 💜 — source/version: ./include/linux, date: October 2026. Slay. 🌈✨