Re: [PATCH 3/5] lib/bitmap: add test for bitmap_{from,to}_arr64

From: Guenter Roeck <linux@roeck-us.net>
To: Yury Norov <yury.norov@gmail.com>
Cc: linux-kernel@vger.kernel.org,
	Alexander Gordeev <agordeev@linux.ibm.com>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Christian Borntraeger <borntraeger@linux.ibm.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Heiko Carstens <hca@linux.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Sven Schnelle <svens@linux.ibm.com>,
	Vasily Gorbik <gor@linux.ibm.com>,
	linux-s390@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH 3/5] lib/bitmap: add test for bitmap_{from,to}_arr64
Date: Sat, 25 Feb 2023 10:47:02 -0800	[thread overview]
Message-ID: <20230225184702.GA3587246@roeck-us.net> (raw)
In-Reply-To: <20220428205116.861003-4-yury.norov@gmail.com>

Hi,

On Thu, Apr 28, 2022 at 01:51:14PM -0700, Yury Norov wrote:
> Test newly added bitmap_{from,to}_arr64() functions similarly to
> already existing bitmap_{from,to}_arr32() tests.
> 
> Signed-off-by: Yury Norov <yury.norov@gmail.com>

Ever since this test is in the tree, several of my boot tests show
lots of messages such as

test_bitmap: bitmap_to_arr64(nbits == 1): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000001)
test_bitmap: bitmap_to_arr64(nbits == 2): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000003)
test_bitmap: bitmap_to_arr64(nbits == 3): tail is not safely cleared: 0xa5a5a5a500000001 (must be 0x0000000000000007)
...
test_bitmap: bitmap_to_arr64(nbits == 927): tail is not safely cleared: 0xa5a5a5a500000000 (must be 0x000000007fffffff)
test_bitmap: bitmap_to_arr64(nbits == 928): tail is not safely cleared: 0xa5a5a5a580000000 (must be 0x00000000ffffffff)

but then:

test_bitmap: all 6550 tests passed

The message suggests an error, given that it is displayed with pr_err,
but the summary suggests otherwise.

Is the message just noise, or is there a problem ?

Thanks,
Guenter

> ---
>  lib/test_bitmap.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
> index 0c82f07f74fc..d5923a640457 100644
> --- a/lib/test_bitmap.c
> +++ b/lib/test_bitmap.c
> @@ -585,6 +585,30 @@ static void __init test_bitmap_arr32(void)
>  	}
>  }
>  
> +static void __init test_bitmap_arr64(void)
> +{
> +	unsigned int nbits, next_bit;
> +	u64 arr[EXP1_IN_BITS / 64];
> +	DECLARE_BITMAP(bmap2, EXP1_IN_BITS);
> +
> +	memset(arr, 0xa5, sizeof(arr));
> +
> +	for (nbits = 0; nbits < EXP1_IN_BITS; ++nbits) {
> +		memset(bmap2, 0xff, sizeof(arr));
> +		bitmap_to_arr64(arr, exp1, nbits);
> +		bitmap_from_arr64(bmap2, arr, nbits);
> +		expect_eq_bitmap(bmap2, exp1, nbits);
> +
> +		next_bit = find_next_bit(bmap2, round_up(nbits, BITS_PER_LONG), nbits);
> +		if (next_bit < round_up(nbits, BITS_PER_LONG))
> +			pr_err("bitmap_copy_arr64(nbits == %d:"
> +				" tail is not safely cleared: %d\n", nbits, next_bit);
> +
> +		if (nbits < EXP1_IN_BITS - 64)
> +			expect_eq_uint(arr[DIV_ROUND_UP(nbits, 64)], 0xa5a5a5a5);
> +	}
> +}
> +
>  static void noinline __init test_mem_optimisations(void)
>  {
>  	DECLARE_BITMAP(bmap1, 1024);
> @@ -852,6 +876,7 @@ static void __init selftest(void)
>  	test_copy();
>  	test_replace();
>  	test_bitmap_arr32();
> +	test_bitmap_arr64();
>  	test_bitmap_parse();
>  	test_bitmap_parselist();
>  	test_bitmap_printlist();
> -- 
> 2.32.0
> 