xas_nomem(9)

📦 version 7.3.1, in nixpkgs unstable

💖 xas_nomem(9) 💖

ok so this is a page from the Kernel API Manual, and today's main character is xas_nomem — she's the "bestie, can you grab me some memory real quick" helper for the XArray. Let's get into it 🎀

✨ NAME ✨

xas_nomem — allocate memory if needed. literally that's it, that's her whole job 💅

🌸 SYNOPSIS 🌸

bool xas_nomem (struct xa_state *xas , gfp_t gfp );

🦋 ARGUMENTS 🦋

  • xas — the XArray operation state. this is the girl holding all the context, she's been through a lot 🫶
  • gfp — the memory allocation flags. the vibes you pass along to the allocator, basically ✨

💜 DESCRIPTION 💜

okay so picture this: we need to add new nodes to the XArray, right? while we're holding the lock, we try to allocate memory with GFP_NOWAIT, and ngl it usually slays and just works 💅

but if it fails — and sometimes it does, it's giving "not today" 😭 — then xas gets flagged as needing memory to continue. that's your cue, bestie: the caller should drop the lock and call xas_nomem. and if xas_nomem succeeds? retry the operation. periodt 🔥

forward progress is guaranteed here, because exactly one node gets allocated at this point and stored in the xa_state, where xas_alloc will find it later. iconic behavior honestly 👑

more nodes will likely be sitting around in the slab allocator, but we do not tie them up here — we're not doing all that, not today 🙈

⭐ RETURN ⭐

true if memory was needed, and was successfully allocated. that's the whole deal 💖

👑 SEE ALSO 👑

Kernel file ./lib/xarray.c — plus the whole friend group, and yes we're listing every single one of them, no skipping 🎀

bestie reminder: if memory was needed and you got it, retry the operation. don't just sit there 😭

🌸 that's the whole page!! brought to you by ./lib, dated October 2026 — mwah, go forth and allocate responsibly 💖✨🎀

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