mmgrab(9)

🦋 mmgrab(9) — Kernel API Manual, bestie edition 💅

okay so welcome to mmgrab(9), aka the Kernel API Manual page that's about to make pinning a &struct mm_struct make sense 💖

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✨ NAME ✨

mmgrab — Pin a &struct mm_struct. Periodt 💅

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🌈 SYNOPSIS 🌈

void mmgrab (struct mm_struct *mm );

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💅 ARGUMENTS 💅

• mm — The struct mm_struct to pin. That's the whole argument, bestie 🫶

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🎀 DESCRIPTION 🎀

Okay so the main character job here: make sure mm will not get freed even after the owning task exits. No cap, that's the whole point 💀

🚨 Important vibe check: this doesn't guarantee that the associated address space will still exist later on. Before you access it, mmget_not_zero has to be used. Periodt.

This is a preferred way to pin mm for a longer/unbounded amount of time. Slay, that's literally what it's for ✨

When you're done and you need to release the reference acquired by mmgrab, use mmdrop — don't leave it hanging, bestie 💅

Also see <Documentation/mm/active_mm.rst> for an in-depth explanation of mm_struct.mm_count vs mm_struct.mm_users. iykyk 🦋

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🔥 SEE ALSO 🔥

Kernel file ./include/linux/sched/mm.h:

• mmget(9)
• might_alloc(9)
• memalloc_flags_save(9)
• memalloc_noio_save(9)
• memalloc_noio_restore(9)
• memalloc_nofs_save(9)
• memalloc_nofs_restore(9)
• memalloc_noreclaim_save(9)
• memalloc_noreclaim_restore(9)
• memalloc_pin_save(9)
• memalloc_pin_restore(9)
• set_active_memcg(9)

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mwah 💋 — source/version ./include/linux/sched, date October 2026, page mmgrab(9). bye bestie 🎀✨