idr_preload(9)

💖 idr_preload(9) 💖

okay so bestie, welcome to the kernel API manual — this one lives in the 9 section and honestly it's a tiny little function with main character energy ✨

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✨ NAME ✨

idr_preload — the preload hook for idr_alloc() 🎀

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🌸 SYNOPSIS 🌸

void idr_preload (gfp_t gfp_mask );

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🦋 ARGUMENTS 🦋

• gfp_t gfp_mask — the allocation mask to use for the preloading, like the whole entire vibe of how you're allowed to grab memory 💅

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🌈 DESCRIPTION 🌈

So the way that this works is: you preallocate memory that's gonna be used for the next call to idr_alloc. That's it, that's the whole gig 🫶

But here's the part where you need to pay attention, bestie — this function returns with preemption disabled. Not a joke, not a drill. 😭 And then idr_preload_end is the one that turns it back on.

🚨 fr fr do not forget the idr_preload_end — preemption stays off until it runs. that's the whole deal, no cap.

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👑 SEE ALSO 👑

While you're here, the kernel file is ./lib/radix-tree.c and there's a whole friend group of related calls you might wanna go say hi to — obsessed with how many there are honestly:

• radix_tree_find_next_bit(9)
• radix_tree_shrink(9)
• __radix_tree_create(9)
• radix_tree_insert(9)
• __radix_tree_lookup(9)
• radix_tree_lookup_slot(9)
• radix_tree_lookup(9)
• __radix_tree_replace(9)
• radix_tree_replace_slot(9)
• radix_tree_iter_replace(9)
• radix_tree_tag_set(9)
• radix_tree_tag_clear(9)
• radix_tree_iter_tag_clear(9)
• radix_tree_tag_get(9)
• radix_tree_next_chunk(9)
• radix_tree_gang_lookup(9)
• radix_tree_gang_lookup_tag(9)
• radix_tree_gang_lookup_tag_slot(9)
• radix_tree_iter_delete(9)
• radix_tree_delete_item(9)
• radix_tree_delete(9)
• radix_tree_tagged(9)
• idr_destroy(9)

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later bestie 💜 this one's from the ./lib corner of the world, dated October 2026, and it's filed under idr_preload(9) — slay ✨