wb_get_create(9)

📦 version 7.3.1, in nixpkgs unstable

💖 wb_get_create — the Kernel API Manual tea 💖

okay so bestie, welcome to the Kernel API Manual entry for wb_get_create(9) — and yes it's giving "small function, big responsibilities" energy and we're gonna get into it 🌸

✨ NAME ✨

wb_get_create — get wb for a given memcg, create if necessary

literally the whole vibe: you want the wb, you maybe don't have the wb, so we make the wb. iconic 💅

🦋 SYNOPSIS 🦋

struct bdi_writeback * wb_get_create (struct backing_dev_info *bdi ,
struct cgroup_subsys_state *memcg_css , gfp_t gfp );

that's the whole signature, no cap — check the return type: a struct bdi_writeback * 🎀

🌈 ARGUMENTS 🌈

  • bdi — the target bdi, like the destination of this whole little journey 💫
  • memcg_css — the cgroup_subsys_state of the target memcg. heads up bestie, it must have positive ref — that's a hard requirement, not a suggestion 🙈
  • gfp — the allocation mask to use 🍓

🧚 DESCRIPTION 🧚

So here's the plot: try to get the wb for memcg_css on bdi. simple enough right?

but if it doesn't exist? bestie, we try to create one. that's the "create if necessary" part of the name doing its thing ✨

and for the deeper lore, the manpage says see wb_get_lookup for more details — so like, if you want the full story, that's where you go 👑

👑 SEE ALSO 👑

Kernel file ./mm/backing-dev.c — that's where the source lives 🫶

💀 friendly reminder from your girl: memcg_css needs a positive ref. don't come crying to me if you skip that. i warned you. periodt.

and that's the page!! 💜 this one comes from the ./mm source, dated October 2026 — so yeah, she's fresh, she's current, she ate and left no crumbs 🌟 byeee 💖🎀

📦 where this page comes from