bitmap_find_free_region(9)

💖 bitmap_find_free_region(9) 💖

okay so this is a page from the Kernel API Manual, and bestie, it's literally about grabbing a nice lil chunk of free space out of a bitmap. it's bitmap_find_free_region, and yes she's iconic 💅

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✨ NAME ✨

bitmap_find_free_region — find a contiguous aligned mem region 🎀

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🌸 SYNOPSIS 🌸

int bitmap_find_free_region (unsigned long *bitmap , unsigned int bits ,
int order );

like, that's the whole signature. short king 🫶

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🦋 ARGUMENTS 🦋

• bitmap — the array of unsigned longs that correspond to the bitmap. this is the thing you're hunting through, no cap.
• bits — how many bits are in the bitmap, fr fr. that's your total playing field.
• order — the region size you wanna find, expressed as log base 2 of the number of bits. so order is giving "the exponent, not the answer" 😭

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💫 DESCRIPTION 💫

so what she does is: find a region of free (zero) bits in a bitmap of bits bits, and then allocate them by setting them to one. periodt. 🎀

and here's the slay part — she only considers regions of length a power (order) of two, aligned to that power of two. the way that makes the search algorithm much faster?? obsessed. ⚡ highkey a vibe.

so yeah, aligned-only. that's not a bug, that's the whole point of the speed. don't come for her 💅

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👑 RETURN 👑

returns the bit offset in bitmap of the allocated region 🌟 — or -errno on failure 😭 (yes, negative errno, watch out for it).

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🔥 SEE ALSO 🔥

kernel file ./include/linux/bitmap.h 🧚

• bitmap overview(9)
• bitmap bitops(9)
• declare bitmap(9)
• bitmap_find_next_zero_area(9)
• bitmap_or_equal(9)
• bitmap_weight_from(9)
• bitmap_scatter(9)
• bitmap_gather(9)
• bitmap_release_region(9)
• bitmap_allocate_region(9)
• BITMAP_FROM_U64(9)
• bitmap_from_u64(9)
• bitmap_read(9)
• bitmap_write(9)

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🌈 okay that's the whole page, bestie! this one's brought to you from ./include/linux, October 2026, and it's bitmap_find_free_region(9) signing off — mwah 💋✨