Re: [PATCH v4 08/20] tools/testing/vma: add tests for copy_vma() self-merge

["David Hildenbrand (Arm)" <david@kernel.org>]

On 8/6/26 22:21, Lorenzo Stoakes (ARM) wrote:
> Assert that a VMA can be moved backwards, forwards and between a preceding
> VMA and its old self.
> 
> In the cases in which the VMA merges only with itself expect that to be
> achieved by expanding its old self, so assert that these function
> correctly.
> 
> However in the case of a merge between a preceding VMA and itself the
> original VMA is removed, so assert that the preceding VMA replaces the one
> passed in as vmap and the merge is as expected.
> 
> Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
> ---
>  tools/testing/vma/tests/vma.c | 46 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 45 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/testing/vma/tests/vma.c b/tools/testing/vma/tests/vma.c
> index 754a2da06321..0d40d7ba2181 100644
> --- a/tools/testing/vma/tests/vma.c
> +++ b/tools/testing/vma/tests/vma.c
> @@ -33,7 +33,51 @@ static bool test_copy_vma(void)
>  	struct mm_struct mm = {};
>  	bool need_locks = false;
>  	VMA_ITERATOR(vmi, &mm, 0);
> -	struct vm_area_struct *vma, *vma_new, *vma_next;
> +	struct vm_area_struct *vma, *vma_prev, *vma_new, *vma_next, *vma_orig;
> +
> +	/* Move forwards, adjacent to old self - self-merge. */
> +
> +	vma = alloc_and_link_vma(&mm, 0x1000, 0x2000, 1, vma_flags);
> +	vma_set_anonymous(vma);
> +	vma_orig = vma;
> +	vma_new = copy_vma(&vma, 0x2000, 0x1000, 1, &need_locks);
> +	ASSERT_EQ(vma_new, vma_orig);
> +	ASSERT_EQ(vma, vma_orig);
> +	ASSERT_EQ(vma_new->vm_start, 0x1000);
> +	ASSERT_EQ(vma_new->vm_end, 0x3000);
> +
> +	cleanup_mm(&mm, &vmi);
> +
> +	/* Move backwards, adjacent to old self - self-merge. */
> +
> +	vma = alloc_and_link_vma(&mm, 0x2000, 0x3000, 2, vma_flags);
> +	vma_set_anonymous(vma);
> +	vma_orig = vma;
> +	vma_new = copy_vma(&vma, 0x1000, 0x1000, 2, &need_locks);
> +	ASSERT_EQ(vma_new, vma_orig);
> +	ASSERT_EQ(vma, vma_orig);
> +	ASSERT_EQ(vma_new->vm_start, 0x1000);
> +	ASSERT_EQ(vma_new->vm_end, 0x3000);
> +
> +	cleanup_mm(&mm, &vmi);
> +
> +	/*
> +	 * Move backwards between prior VMA and old self - self-merge and vma
> +	 * updated to a new VMA.
> +	 */
> +
> +	vma_prev = alloc_and_link_vma(&mm, 0x1000, 0x2000, 1, vma_flags);
> +	vma_set_anonymous(vma_prev);
> +	vma = alloc_and_link_vma(&mm, 0x3000, 0x4000, 3, vma_flags);
> +	vma_set_anonymous(vma);
> +	vma_orig = vma;
> +	vma_new = copy_vma(&vma, 0x2000, 0x1000, 3, &need_locks);
> +	ASSERT_NE(vma_new, vma_orig);
> +	ASSERT_EQ(vma_new, vma);
> +	ASSERT_EQ(vma_new->vm_start, 0x1000);
> +	ASSERT_EQ(vma_new->vm_end, 0x4000);
> +
> +	cleanup_mm(&mm, &vmi);

Okay, these examples were pretty useful to understand the original problem.

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David