shmem_writeout(9)

💅 shmem_writeout — a kernel API manual, but make it make sense

okay so bestie, you found your way to shmem_writeout(9), the third section (kernel API) manual page. pull up a chair, grab a strawberry 🍓, and let's get into it — this one's short but she's iconic.

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✨ NAME ✨

shmem_writeout — literally just: write the folio to swap. that's the whole vibe. 💫

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🦋 SYNOPSIS 🦋

int shmem_writeout (struct swap_io_ctx *ctx , struct folio *folio ,
       struct list_head *folio_list );

like yes, it returns an int, and yes, those are the exact parameters, don't @ me.

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🎀 ARGUMENTS 🎀

• ctx — the swap I/O context. she's the whole situation, the group chat the operation happens in. 🫶
• folio — the folio to write. the main character, fr fr. 👑
• folio_list — the list to put back folios on split. yes, "on split" — that's the exact wording, i'm not making this up. 😭

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🔥 DESCRIPTION 🔥

move the folio from the page cache to the swap cache. that's it. that's the description. no cap, no extra lore, just a relocation. the way that she just moves 💅

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🌈 SEE ALSO 🌈

• kernel file ./mm/shmem.c
• shmem_recalc_inode(9)
• shmem_get_folio(9)
• shmem_kernel_file_setup(9)
• shmem_file_setup(9)
• shmem_file_setup_with_mnt(9)
• shmem_zero_setup(9)
• shmem_zero_setup_desc(9)
• shmem_read_folio_gfp(9)

go read those too, iykyk 📚✨

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lowkey a warning-ish thing: the manpage doesn't editorialize here, but do note the folio_list argument exists specifically for putting folios back on split — don't just pass garbage, bestie. 🙈

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and that's the page!! 🧚 source/version: ./mm, dated October 2026, and the whole thing is filed under shmem_writeout(9). mwah, go write some folios 💜🌸