Re: [PATCH] bitmap: Properly initialise destination bitmap for scatter & gather test

[Yury Norov]

On Thu, Jul 09, 2026 at 01:40:06PM +0200, Christophe Leroy (CS GROUP) wrote:
> Erhard reports failure of bitmap tests on powerpc:
> 
>   test_bitmap: loaded.
>   test_bitmap: [lib/test_bitmap.c:397] bitmaps contents differ: expected "1,3-4,9", got "1,3-4,9,65-71,73-79,81-87,89-95,97-99"
>   test_bitmap: parselist('0-2047:128/256'):    912
>   test_bitmap: scnprintf("%*pbl", '0-32767'):    5977
>   test_bitmap: test_bitmap_read_perf:        1191082
>   test_bitmap: test_bitmap_write_perf:        1270153
>   test_bitmap: failed 1 out of 208655 tests
> 
> The happens mainly when CONFIG_INIT_STACK_ALL_PATTERN is set.
> 
> Commit 6b5a4b687367 ("bitmap: Add test for out-of-boundary
> modifications for scatter & gather") extended the test to
> out-of-boundary bits, but those bits where left uninitialised.
> 
> Properly initialise the entire result bitmap before the test.
> 
> Reported-by: Erhard Furtner <erhard_f@xxxxxxxxxxx>
> Closes: https://lore.kernel.org/all/ca3547ae-8b79-43a2-a758-23ec980bfd9a@xxxxxxxxxxx
> Fixes: 6b5a4b687367 ("bitmap: Add test for out-of-boundary modifications for scatter & gather")
> Signed-off-by: Christophe Leroy (CS GROUP) <chleroy@xxxxxxxxxx>

Applied, thanks!

> ---
>  lib/test_bitmap.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> index 69813c10e6c0..448c3eb48a4a 100644
> --- a/lib/test_bitmap.c
> +++ b/lib/test_bitmap.c
> @@ -392,6 +392,7 @@ static void __init test_bitmap_sg(void)
>  
>  	/* Scatter/gather relationship */
>  	bitmap_zero(bmap_tmp, 100);
> +	bitmap_zero(bmap_res, 100);
>  	bitmap_gather(bmap_tmp, bmap_scatter, sg_mask, nbits);
>  	bitmap_scatter(bmap_res, bmap_tmp, sg_mask, nbits);
>  	expect_eq_bitmap(bmap_scatter, bmap_res, 100);
> -- 
> 2.54.0