Re: [PATCH v8 6/6] lib/test_vmalloc: add vrealloc test case

[Uladzislau Rezki <urezki@gmail.com>]

On Fri, Mar 27, 2026 at 03:18:42PM +0530, Shivam Kalra via B4 Relay wrote:
> From: Shivam Kalra <shivamkalra98@zohomail.in>
> 
> Introduce a new test case "vrealloc_test" that exercises the vrealloc()
> shrink and in-place grow paths:
> 
>   - Grow beyond allocated pages (triggers full reallocation).
>   - Shrink crossing a page boundary (frees tail pages).
>   - Shrink within the same page (no page freeing).
>   - Grow within the already allocated page count (in-place).
> 
> Data integrity is validated after each realloc step by checking that
> the first byte of the original allocation is preserved.
> 
> The test is gated behind run_test_mask bit 12 (id 4096).
> 
> Signed-off-by: Shivam Kalra <shivamkalra98@zohomail.in>
> ---
>  lib/test_vmalloc.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 62 insertions(+)
> 
> diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
> index 876c72c18a0c..b23f85e8f8ca 100644
> --- a/lib/test_vmalloc.c
> +++ b/lib/test_vmalloc.c
> @@ -55,6 +55,7 @@ __param(int, run_test_mask, 7,
>  		"\t\tid: 512,  name: kvfree_rcu_2_arg_vmalloc_test\n"
>  		"\t\tid: 1024, name: vm_map_ram_test\n"
>  		"\t\tid: 2048, name: no_block_alloc_test\n"
> +		"\t\tid: 4096, name: vrealloc_test\n"
>  		/* Add a new test case description here. */
>  );
>  
> @@ -421,6 +422,66 @@ vm_map_ram_test(void)
>  	return nr_allocated != map_nr_pages;
>  }
>  
> +static int vrealloc_test(void)
> +{
> +	void *ptr, *tmp;
> +	int i;
> +
> +	for (i = 0; i < test_loop_count; i++) {
> +		int err = -1;
> +
> +		ptr = vrealloc(NULL, PAGE_SIZE, GFP_KERNEL);
> +		if (!ptr)
> +			return -1;
> +
> +		*((__u8 *)ptr) = 'a';
> +
> +		/* Grow: beyond allocated pages, triggers full realloc. */
> +		tmp = vrealloc(ptr, 4 * PAGE_SIZE, GFP_KERNEL);
> +		if (!tmp)
> +			goto error;
> +		ptr = tmp;
> +
> +		if (*((__u8 *)ptr) != 'a')
> +			goto error;
> +
> +		/* Shrink: crosses page boundary, frees tail pages. */
> +		tmp = vrealloc(ptr, PAGE_SIZE, GFP_KERNEL);
> +		if (!tmp)
> +			goto error;
> +		ptr = tmp;
> +
> +		if (*((__u8 *)ptr) != 'a')
> +			goto error;
> +
> +		/* Shrink: within same page, no page freeing. */
> +		tmp = vrealloc(ptr, PAGE_SIZE / 2, GFP_KERNEL);
> +		if (!tmp)
> +			goto error;
> +		ptr = tmp;
> +
> +		if (*((__u8 *)ptr) != 'a')
> +			goto error;
> +
> +		/* Grow: within allocated page, in-place, no realloc. */
> +		tmp = vrealloc(ptr, PAGE_SIZE, GFP_KERNEL);
> +		if (!tmp)
> +			goto error;
> +		ptr = tmp;
> +
> +		if (*((__u8 *)ptr) != 'a')
> +			goto error;
> +
> +		err = 0;
> +error:
> +		vfree(ptr);
> +		if (err)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +
>  struct test_case_desc {
>  	const char *test_name;
>  	int (*test_func)(void);
> @@ -440,6 +501,7 @@ static struct test_case_desc test_case_array[] = {
>  	{ "kvfree_rcu_2_arg_vmalloc_test", kvfree_rcu_2_arg_vmalloc_test, },
>  	{ "vm_map_ram_test", vm_map_ram_test, },
>  	{ "no_block_alloc_test", no_block_alloc_test, true },
> +	{ "vrealloc_test", vrealloc_test, },
>  	/* Add a new test case here. */
>  };
>  
> 
> -- 
> 2.43.0
> 
> 
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>

--
Uladzislau Rezki