swap_cache_has_folio(9)

💅 swap_cache_has_folio(9) 💅

okay so real talk, this is a page from the Kernel API Manual and honestly? it's a little one but she's important. literally the vibe check for swap slots. let's get into it 🫶

---

✨ NAME ✨

swap_cache_has_folio — bestie, this one checks if a swap slot has cache. that's the whole job. no cap. 💖

---

🌸 SYNOPSIS 🌸

bool swap_cache_has_folio (swp_entry_t entry );

it returns a bool, she takes exactly one thing, and she is not complicated. iconic behavior honestly ✨

---

🎀 ARGUMENTS 🎀

• entry — a swap entry that's pointing at the slot you're curious about. that's it, that's the argument. she's just here to tell you which slot we're talking about 🔥

---

💀 CONTEXT 💀

okay this part is the serious part, listen up:

the caller must make sure entry is valid, and must protect the swap device either with a reference count or with locks. like, that's on you, not on her. she's not doing the vibes-checking for you 🙈

no like fr fr, don't skip this bit. validity + protection (refcount or locks) is the whole prerequisite. don't be that person 😭

---

🦋 SEE ALSO 🦋

she does not exist in a vacuum, she's got a whole friend group:

• the kernel file ./mm/swap_state.c — that's where she lives, that's her home 🏠
• swap_cache_get_folio(9)
• swap_cache_get_shadow(9)
• __swap_cache_add_check(9)
• __swap_cache_add_folio(9)
• __swap_cache_del_folio(9)
• swap_cache_del_folio(9)
• __swap_cache_replace_folio(9)
• swap_cache_alloc_folio(9)
• swap_update_readahead(9)
• swapin_sync(9)
• swap_cluster_readahead(9)
• swap_vma_readahead(9)
• swapin_readahead(9)

like she literally ate and left crumbs, go read the whole squad 👑

---

and that's the page!! 💜

cute little sign-off moment: this whole thing comes from ./mm, dated October 2026, and yes she's filed under swap_cache_has_folio(9) for all your future reference needs 🍓✨ mwah, go touch some folios 🧚