Messages in this thread Patch in this message | | | Date | Tue, 7 Jun 2022 14:42:09 -0400 | Subject | [PATCH v6 04/11] dmapool: fix boundary comparison | From | Tony Battersby <> |
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Fix the boundary comparison when constructing the list of free blocks for the case that 'size' is a power of two. Since 'boundary' is also a power of two, that would make 'boundary' a multiple of 'size', in which case a single block would never cross the boundary. This bug would cause some of the allocated memory to be wasted (but not leaked).
Example:
size = 512 boundary = 2048 allocation = 4096
Address range 0 - 511 512 - 1023 1024 - 1535 1536 - 2047 * 2048 - 2559 2560 - 3071 3072 - 3583 3584 - 4095 *
Prior to this fix, the address ranges marked with "*" would not have been used even though they didn't cross the given boundary.
Fixes: e34f44b3517f ("pool: Improve memory usage for devices which can't cross boundaries") Signed-off-by: Tony Battersby <tonyb@cybernetics.com> --- mm/dmapool.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/dmapool.c b/mm/dmapool.c index f85d6bde2205..122781fe2c03 100644 --- a/mm/dmapool.c +++ b/mm/dmapool.c @@ -201,7 +201,7 @@ static void pool_initialise_page(struct dma_pool *pool, struct dma_page *page) do { unsigned int next = offset + pool->size; - if (unlikely((next + pool->size) >= next_boundary)) { + if (unlikely((next + pool->size) > next_boundary)) { next = next_boundary; next_boundary += pool->boundary; } -- 2.25.1
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