[ 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: Dennis Zhou <den...@kernel.org>
Reviewed-by: Peng Fan <peng....@nxp.com>
Signed-off-by: Sasha Levin <sas...@kernel.org>
---
mm/percpu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/percpu.c b/mm/percpu.c
index bc58bcbe4b60..9beb84800d8d 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -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,
+ 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)
--
2.20.1
