pin_hibernation_swap_type(9)

💖 pin_hibernation_swap_type(9) 💖

okay so bestie, welcome to the Kernel API Manual — yes we're reading kernel docs together, this is our bonding era 🫶. Today's main character is pin_hibernation_swap_type, and ngl, it's giving "tiny function, huge responsibility."

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✨ NAME ✨

pin_hibernation_swap_type — pin the swap device for hibernation 🔒💤

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🌸 SYNOPSIS 🌸

int pin_hibernation_swap_type (dev_t device , sector_t offset );

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🎀 ARGUMENTS 🎀

• device — the block device that's holding the resume image 👀
• offset — the offset that identifies the swap area, a.k.a. the "which swap area tho" coordinate 📍

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🦋 DESCRIPTION 🦋

So here's the vibe: it goes and locates the swap device that matches device/offset, then marks it as pinned for hibernation. While it's pinned, swapoff is prevented — like, absolutely not, we're not doing that right now 💅.

And listen, bestie, there's a limit here: only one uswsusp context may pin a swap device at a time. That's the rule. If it's already pinned, this function just returns -EBUSY and moves on. No drama, just a hard no 🙈.

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🔥 RETURN 🔥

• >= 0 — success, and you get the swap type back ✨
• -EINVAL — device is invalid, like girl what even is that 😭
• -ENODEV — the swap device was not found, it's literally not here 💀
• -EBUSY — the device is already pinned for hibernation, someone else got here first 👑

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👑 SEE ALSO 👑

Kernel file ./mm/swapfile.c — and the whole friend group:

swap_put_entries_cluster(9), swap_dup_entries_cluster(9), folio_alloc_swap(9), folio_dup_swap(9), folio_put_swap(9), swap_entry_swapped(9), folio_free_swap(9), swap_put_entries_direct(9), swap_alloc_hibernation_slot(9), swap_free_hibernation_slot(9), unpin_hibernation_swap_type(9), find_hibernation_swap_type(9)

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🌈 friendly reminder: pinning is a commitment. Only one uswsusp context at a time, iykyk.

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and that's the whole page, bestie, you ate 🍓✨ — this iconic little number lives in ./mm, dated October 2026, and it's filed under pin_hibernation_swap_type(9). mwah 💋🧚💜