Commit 6a5abd6b 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 8c43004a ]

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 <dennis@kernel.org>
Reviewed-by: default avatarPeng Fan <peng.fan@nxp.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent e92c1e9a
...@@ -988,7 +988,8 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits, ...@@ -988,7 +988,8 @@ static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
/* /*
* Search to find a fit. * Search to find a fit.
*/ */
end = start + alloc_bits + PCPU_BITMAP_BLOCK_BITS; end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
pcpu_chunk_map_bits(chunk));
bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start, bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start,
alloc_bits, align_mask); alloc_bits, align_mask);
if (bit_off >= end) if (bit_off >= end)
......
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