discard_a_page(9)

📦 version 7.3.1, in nixpkgs unstable

💅 discard_a_page(9) — like, the Kernel API Manual page, bestie

okay so this is discard_a_page from the Kernel API Manual, and honestly? it's the opening move of throwing a page away. the beginning of the discard journey. main character energy for a cleanup routine ✨

🌸 SYNOPSIS 🌸

void discard_a_page (struct vdo_page_cache *cache );

that's it. one function, one arg, void return, no cap. 🫶

🎀 ARGUMENTS 🎀

  • cache — the page cache. yes, the page cache. that's the whole vibe check on this one 💖

🦋 DESCRIPTION 🦋

so here's the tea ☕ — if there's, like, no page that's discardable, this function bumps up a count of deferred frees. why? so that the next time a page gets released and it's no longer busy, it'll kick off another whole discard cycle. basically a little nudge note to future-you 📝

and what does that count mean, you ask? it's an indication that the cache is not big enough. literally the cache sending you a hint. disrespectful but valid 💀

now, if the selected page is not dirty? the function immediately allocates that page to the oldest completion waiting for a free page. first come, first served, we love a fair queue 👑

no cap, keep both of these behaviours in mind — one path defers, the other path hands the page straight to whoever's been waiting the longest. two totally different vibes from one tiny function 🌈

⭐ SEE ALSO ⭐

the whole friend group, fr fr. first up the file it lives in:

  • Kernel file ./drivers/md/dm-vdo/block-map.c

then the squad, in the exact order the manual lists them:

like, that's the entire group chat and every single one of them is iconic 💜

and that's the page, bestie! 🧚 this lil beauty comes from ./drivers/md/dm-vdo, dated October 2026, and it's filed under discard_a_page(9). go read some more kernel docs, you're doing amazing 🍓✨

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