Commit 4794604a authored by Dennis Zhou's avatar Dennis Zhou Committed by Greg Kroah-Hartman

percpu: do not search past bitmap when allocating an area

[ Upstream commit 8c43004af01635cc9fbb11031d070e5e0d327ef2 ]

pcpu_find_block_fit() guarantees that a fit is found within
PCPU_BITMAP_BLOCK_BITS. Iteration is used to determine the first fit as
it compares against the block's contig_hint. This can lead to
incorrectly scanning past the end of the bitmap. The behavior was okay
given the check after for bit_off >= end and the correctness of the
hints from pcpu_find_block_fit().

This patch fixes this by bounding the end offset by the number of bits
in a chunk.
Signed-off-by: default avatarDennis Zhou <>
Reviewed-by: Peng Fan's avatarPeng Fan <>
Signed-off-by: default avatarSasha Levin <>
parent 3e729a2c
......@@ -984,7 +984,8 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
* Search to find a fit.
end = start + alloc_bits + PCPU_BITMAP_BLOCK_BITS;
end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start,
alloc_bits, align_mask);
if (bit_off >= end)
Markdown is supported
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment