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Commit 526972e9 authored by Dennis Zhou's avatar Dennis Zhou Committed by Greg Kroah-Hartman
Browse files

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 <dennis@kernel.org>
Reviewed-by: default avatarPeng Fan <peng.fan@nxp.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent d4d5dce6

mm/percpu.c

+2 −1
Original line number Diff line number Diff line
@@ -988,7 +988,8 @@ 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,

		    pcpu_chunk_map_bits(chunk));

	bit_off = bitmap_find_next_zero_area(chunk->alloc_map, end, start,

					     alloc_bits, align_mask);

	if (bit_off >= end)