STRUCT DMEM_CGROUP_OPS(9)

💅 struct dmem_cgroup_ops(9) 💅

okay so this is a page from the Kernel API Manual, and it's all about one little struct: struct dmem_cgroup_ops — literally the operations table for a dmem cgroup region. bestie, it's giving "small but mighty." 🎀

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✨ NAME ✨

struct dmem_cgroup_ops — the operations for a dmem cgroup region. that's it, that's the whole vibe. 🦋

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🌸 SYNOPSIS 🌸

struct dmem_cgroup_ops {
    int (*reclaim)(struct dmem_cgroup_pool_state *pool, u64
target_bytes, void *priv);
 };

look at her. one function pointer. main character energy honestly. 👑

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💖 Members 💖

• reclaim — this one's optional (so no pressure, but also… slay if you implement it 💅). it's the callback that gets invoked when dmem.max is set below the current usage of a pool. when that happens, the driver should attempt to free at least target_bytes from pool. and heads up — it may get called multiple times if usage is still above the limit after it returns. so like, don't assume it's a one-and-done situation, okay? 🔥

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🌈 Return 🌈

the return value of reclaim is doing a whole lot of storytelling, so let's break it down:

• 0 — some progress was made. yes, even if you freed less than target_bytes. progress is progress, we celebrate it 🫶
• -ENOSPC — no progress could be made at all. the caller will retry, but only up to a bounded number of times, so don't get too comfy 😭
• another negative error code — a fatal error happened. this stops further reclaim attempts immediately. like, hard stop. no more retries. 💀

fr fr, that last one is the dramatic exit — once you return a fatal negative error, the reclaim party is over.

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🧚 SEE ALSO 🧚

• Kernel file ./include/linux/cgroup_dmem.h
• struct dmem_cgroup_init(9)

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that's the whole page, babes — go forth and reclaim responsibly ✨💜

— with love, from ./include/linux, October 2026 edition of the Kernel API Manual 🎀🦋