ttm_bo_reserve_slowpath(9)

💅 ttm_bo_reserve_slowpath — Kernel API Manual, bestie edition

okay so real talk, this is ttm_bo_reserve_slowpath(9) from the kernel API manual, and the strict-lore girlies already know this is the redemption-arc function of the TTM buffer object world. let's get into it ✨

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🌸 NAME 🌸

ttm_bo_reserve_slowpath —

no because the original literally leaves the description blank after that dash 😭 the manpage said "figure it out" and honestly? iconic. anyway the name is the name, and it's the slowpath version of reserving. you'll get it in a sec 🫶

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✨ SYNOPSIS ✨

int ttm_bo_reserve_slowpath (struct ttm_buffer_object *bo , bool
interruptible , struct ww_acquire_ctx *ticket );

three args, one int back, no drama 💅

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🎀 ARGUMENTS 🎀

• bo — a pointer to a struct ttm_buffer_object. the buffer object in question, the main character of this whole operation 👑
• interruptible — a bool. when it's waiting, it sleeps interruptible if you set this. so like, you can still be woken up while it naps 💤
• ticket — the ticket used to acquire the ww_mutex. yes bestie, the ticket, the whole karma system, it's how the wound/wait mutex does its thing 🎟️

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🦋 DESCRIPTION 🦋

kay so here's the lore: this function gets called after ttm_bo_reserve comes back with -EAGAIN and we've backed off from all our other reservations. not me releasing everything before trying again, self-care honestly 🧖‍♀️

and because there are no other reservations held by us at that point, this function cannot deadlock any more. can't deadlock, won't deadlock, periodt. 🔥 no cap, that's the whole point of the back-off — you drop your other holds, then you come back for this one clean 💀

fr fr though: -EAGAIN from ttm_bo_reserve → back off from all your other reservations → then ttm_bo_reserve_slowpath because the deadlock risk is gone. that's the vibe check ✅

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🌈 SEE ALSO 🌈

the whole friend group, gathered:

• kernel file ./include/drm/ttm/ttm_bo.h
• enum ttm_bo_type(9)
• struct ttm_buffer_object(9)
• struct ttm_bo_kmap_obj(9)
• struct ttm_operation_ctx(9)
• struct ttm_lru_walk_arg(9)
• struct ttm_lru_walk(9)
• struct ttm_bo_shrink_flags(9)
• ttm_bo_reserve(9)
• ttm_bo_move_null(9)
• ttm_bo_unreserve(9)
• ttm_kmap_obj_virtual(9)
• struct ttm_bo_lru_cursor(9)
• ttm_bo_lru_for_each_reserved_guarded(9)

literally all of them, linked and everything, iykyk 💖

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⭐ sign-off ⭐

that's the page bestie 🫶 it came from ./include/drm/ttm and it's dated October 2026, so mark your calendar, mwah 💋