RE: [PATCH 5.15.y 1/2] mm/damon/vaddr-test: split a test function having >1024 bytes frame size

[David Laight <David.Laight@ACULAB.COM>]

From: SeongJae Park
> Sent: 06 December 2024 18:16
> 
> On some configuration[1], 'damon_test_split_evenly()' kunit test
> function has >1024 bytes frame size, so below build warning is
> triggered:
> 
>       CC      mm/damon/vaddr.o
>     In file included from mm/damon/vaddr.c:672:
>     mm/damon/vaddr-test.h: In function 'damon_test_split_evenly':
>     mm/damon/vaddr-test.h:309:1: warning: the frame size of 1064 bytes is larger than 1024 bytes [-
> Wframe-larger-than=]
>       309 | }
>           | ^
> 
> This commit fixes the warning by separating the common logic in the
> function.

In that guaranteed to make any difference without some noinline_for_stack
attributes?

Not that I can see exactly where the stack was used.
But it tends to be clang that doesn't re-use stack space.

	David

> 
> [1] https://lore.kernel.org/linux-mm/202111182146.OV3C4uGr-lkp@intel.com/
> 
> Link: https://lkml.kernel.org/r/20211201150440.1088-6-sj@kernel.org
> Fixes: 17ccae8bb5c9 ("mm/damon: add kunit tests")
> Signed-off-by: SeongJae Park <sj@kernel.org>
> Reported-by: kernel test robot <lkp@intel.com>
> Cc: Brendan Higgins <brendanhiggins@google.com>
> Cc: Shuah Khan <shuah@kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> (cherry picked from commit 044cd9750fe010170f5dc812e4824d98f5ea928c)
> ---
>  mm/damon/vaddr-test.h | 77 ++++++++++++++++++++++---------------------
>  1 file changed, 40 insertions(+), 37 deletions(-)
> 
> diff --git a/mm/damon/vaddr-test.h b/mm/damon/vaddr-test.h
> index 1f5c13257dba..95ec362cdc37 100644
> --- a/mm/damon/vaddr-test.h
> +++ b/mm/damon/vaddr-test.h
> @@ -252,59 +252,62 @@ static void damon_test_apply_three_regions4(struct kunit *test)
>  			new_three_regions, expected, ARRAY_SIZE(expected));
>  }
> 
> -static void damon_test_split_evenly(struct kunit *test)
> +static void damon_test_split_evenly_fail(struct kunit *test,
> +		unsigned long start, unsigned long end, unsigned int nr_pieces)
>  {
> -	struct damon_ctx *c = damon_new_ctx();
> -	struct damon_target *t;
> -	struct damon_region *r;
> -	unsigned long i;
> -
> -	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(NULL, NULL, 5),
> -			-EINVAL);
> -
> -	t = damon_new_target(42);
> -	r = damon_new_region(0, 100);
> -	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 0), -EINVAL);
> +	struct damon_target *t = damon_new_target(42);
> +	struct damon_region *r = damon_new_region(start, end);
> 
>  	damon_add_region(r, t);
> -	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 10), 0);
> -	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 10u);
> +	KUNIT_EXPECT_EQ(test,
> +			damon_va_evenly_split_region(t, r, nr_pieces), -EINVAL);
> +	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1u);
> 
> -	i = 0;
>  	damon_for_each_region(r, t) {
> -		KUNIT_EXPECT_EQ(test, r->ar.start, i++ * 10);
> -		KUNIT_EXPECT_EQ(test, r->ar.end, i * 10);
> +		KUNIT_EXPECT_EQ(test, r->ar.start, start);
> +		KUNIT_EXPECT_EQ(test, r->ar.end, end);
>  	}
> +
>  	damon_free_target(t);
> +}
> +
> +static void damon_test_split_evenly_succ(struct kunit *test,
> +	unsigned long start, unsigned long end, unsigned int nr_pieces)
> +{
> +	struct damon_target *t = damon_new_target(42);
> +	struct damon_region *r = damon_new_region(start, end);
> +	unsigned long expected_width = (end - start) / nr_pieces;
> +	unsigned long i = 0;
> 
> -	t = damon_new_target(42);
> -	r = damon_new_region(5, 59);
>  	damon_add_region(r, t);
> -	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 5), 0);
> -	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 5u);
> +	KUNIT_EXPECT_EQ(test,
> +			damon_va_evenly_split_region(t, r, nr_pieces), 0);
> +	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), nr_pieces);
> 
> -	i = 0;
>  	damon_for_each_region(r, t) {
> -		if (i == 4)
> +		if (i == nr_pieces - 1)
>  			break;
> -		KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i++);
> -		KUNIT_EXPECT_EQ(test, r->ar.end, 5 + 10 * i);
> +		KUNIT_EXPECT_EQ(test,
> +				r->ar.start, start + i++ * expected_width);
> +		KUNIT_EXPECT_EQ(test, r->ar.end, start + i * expected_width);
>  	}
> -	KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i);
> -	KUNIT_EXPECT_EQ(test, r->ar.end, 59ul);
> +	KUNIT_EXPECT_EQ(test, r->ar.start, start + i * expected_width);
> +	KUNIT_EXPECT_EQ(test, r->ar.end, end);
>  	damon_free_target(t);
> +}
> 
> -	t = damon_new_target(42);
> -	r = damon_new_region(5, 6);
> -	damon_add_region(r, t);
> -	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 2), -EINVAL);
> -	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1u);
> +static void damon_test_split_evenly(struct kunit *test)
> +{
> +	struct damon_ctx *c = damon_new_ctx();
> +
> +	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(NULL, NULL, 5),
> +			-EINVAL);
> +
> +	damon_test_split_evenly_fail(test, 0, 100, 0);
> +	damon_test_split_evenly_succ(test, 0, 100, 10);
> +	damon_test_split_evenly_succ(test, 5, 59, 5);
> +	damon_test_split_evenly_fail(test, 5, 6, 2);
> 
> -	damon_for_each_region(r, t) {
> -		KUNIT_EXPECT_EQ(test, r->ar.start, 5ul);
> -		KUNIT_EXPECT_EQ(test, r->ar.end, 6ul);
> -	}
> -	damon_free_target(t);
>  	damon_destroy_ctx(c);
>  }
> 
> --
> 2.39.5
> 

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)