obj_cgroup_may_zswap(9)

💖 NAME 💖

okay so welcome to the Kernel API Manual, bestie ✨ this is the page for obj_cgroup_may_zswap — literally “check if this cgroup can zswap.”

It’s the quick vibe check before anything gets too excited about compressing stuff. 🦋

✨ SYNOPSIS ✨

bool obj_cgroup_may_zswap (struct obj_cgroup *objcg );

🎀 ARGUMENTS 🎀

• objcg — the object cgroup. yep, that’s the object cgroup getting checked. 🫶

🌸 DESCRIPTION 🌸

Check if the hierarchical zswap limit has been reached. that’s the mission, no cap.

Caveat time, because bestie we keep it real: this doesn’t check for specific headroom, and it is not atomic either. so like, it’s a snapshot vibe, not a guarantee that holds forever. 💀

But with zswap, the size of the allocation is only known once compression has occurred, and this optimistic pre-check avoids spending cycles on compression when there is already no room left or zswap is disabled altogether somewhere in the hierarchy. it’s giving “why compress if the answer is already no?” 🔥

🌈 SEE ALSO 🌈

Kernel file ./mm/memcontrol.c — and the whole reference friend group is right here:

• get_mem_cgroup_css_from_folio(9)
• page_cgroup_ino(9)
• lruvec_page_state_monotonic(9)
• mod_memcg_state(9)
• mod_lruvec_state(9)
• count_memcg_events(9)
• get_mem_cgroup_from_mm(9)
• get_mem_cgroup_from_current(9)
• get_mem_cgroup_from_folio(9)
• mem_cgroup_iter(9)
• mem_cgroup_iter_break(9)
• mem_cgroup_scan_tasks(9)
• folio_lruvec_lock(9)
• folio_lruvec_lock_irq(9)
• folio_lruvec_lock_irqsave(9)
• mem_cgroup_update_lru_size(9)
• mem_cgroup_margin(9)
• mem_cgroup_print_oom_context(9)
• mem_cgroup_print_oom_meminfo(9)
• mem_cgroup_get_oom_group(9)
• consume_stock(9)
• __memcg_kmem_charge_page(9)
• __memcg_kmem_uncharge_page(9)
• mem_cgroup_wb_stats(9)
• mem_cgroup_from_private_id(9)
• mem_cgroup_css_reset(9)
• mem_cgroup_calculate_protection(9)
• mem_cgroup_charge_hugetlb(9)
• mem_cgroup_swapin_charge_folio(9)
• mem_cgroup_replace_folio(9)
• mem_cgroup_migrate(9)
• mem_cgroup_sk_charge(9)
• mem_cgroup_sk_uncharge(9)
• __mem_cgroup_try_charge_swap(9)
• __mem_cgroup_uncharge_swap(9)
• obj_cgroup_charge_zswap(9)
• obj_cgroup_uncharge_zswap(9)

that’s the whole page, bestie 💅 this one lives in the ./mm source tree, carries the October 2026 date, and belongs to the Kernel API Manual as obj_cgroup_may_zswap(9). mwah 🍓