linux-kernel - Re: [PATCH v3 2/2] lib/test_vmalloc.c: Add vm_map_ram()/vm_unmap

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Message-ID: <68791932-5e23-4afd-9b36-6cc9a310fdd5@lucifer.local>
Date:   Mon, 27 Mar 2023 21:28:00 +0100
From:   Lorenzo Stoakes <lstoakes@...il.com>
To:     "Uladzislau Rezki (Sony)" <urezki@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        LKML <linux-kernel@...r.kernel.org>, Baoquan He <bhe@...hat.com>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Dave Chinner <david@...morbit.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH v3 2/2] lib/test_vmalloc.c: Add
 vm_map_ram()/vm_unmap_ram() test case

On Mon, Mar 27, 2023 at 07:01:26PM +0200, Uladzislau Rezki (Sony) wrote:
> Add vm_map_ram()/vm_unmap_ram() test case to our stress test-suite.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
> ---
>  lib/test_vmalloc.c | 41 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 41 insertions(+)
>
> diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
> index cd2bdba6d3ed..6633eda4cd4d 100644
> --- a/lib/test_vmalloc.c
> +++ b/lib/test_vmalloc.c
> @@ -53,6 +53,7 @@ __param(int, run_test_mask, INT_MAX,
>  		"\t\tid: 128,  name: pcpu_alloc_test\n"
>  		"\t\tid: 256,  name: kvfree_rcu_1_arg_vmalloc_test\n"
>  		"\t\tid: 512,  name: kvfree_rcu_2_arg_vmalloc_test\n"
> +		"\t\tid: 1024, name: vm_map_ram_test\n"
>  		/* Add a new test case description here. */
>  );
>
> @@ -358,6 +359,45 @@ kvfree_rcu_2_arg_vmalloc_test(void)
>  	return 0;
>  }
>
> +static int
> +vm_map_ram_test(void)
> +{
> +	unsigned int map_nr_pages;
> +	unsigned char *v_ptr;
> +	unsigned char *p_ptr;
> +	struct page **pages;
> +	struct page *page;
> +	int i;
> +
> +	map_nr_pages = nr_pages > 0 ? nr_pages:1;
> +	pages = kmalloc(map_nr_pages * sizeof(*page), GFP_KERNEL);
> +	if (!pages)
> +		return -1;
> +
> +	for (i = 0; i < map_nr_pages; i++) {
> +		page = alloc_pages(GFP_KERNEL, 1);

Pedantry, but given I literally patched this pedantically the other day,
this could be alloc_page(GFP_KERNEL) :)

> +		if (!page)
> +			return -1;

We're leaking memory here right? Should jump to cleanup below.

> +
> +		pages[i] = page;
> +	}


You should be able to replace this with something like:-

unsigned long nr_allocated;

...

nr_allocated = alloc_pages_bulk_array(GFP_KERNEL, map_nr_pages, pages);
if (nr_allocated != map_nr_pages)
	goto cleanup;

> +
> +	/* Run the test loop. */
> +	for (i = 0; i < test_loop_count; i++) {
> +		v_ptr = vm_map_ram(pages, map_nr_pages, -1);

NIT: The -1 would be clearer as NUMA_NO_NODE

> +		*v_ptr = 'a';
> +		vm_unmap_ram(v_ptr, map_nr_pages);
> +	}
> +

Reference to the above you'd add the cleanup label here:-

cleanup:

> +	for (i = 0; i < map_nr_pages; i++) {
> +		p_ptr = page_address(pages[i]);
> +		free_pages((unsigned long)p_ptr, 1);

Nit, can be free_page((unsigned long)p_ptr);

> +	}
> +
> +	kfree(pages);
> +	return 0;
> +}
> +
>  struct test_case_desc {
>  	const char *test_name;
>  	int (*test_func)(void);
> @@ -374,6 +414,7 @@ static struct test_case_desc test_case_array[] = {
>  	{ "pcpu_alloc_test", pcpu_alloc_test },
>  	{ "kvfree_rcu_1_arg_vmalloc_test", kvfree_rcu_1_arg_vmalloc_test },
>  	{ "kvfree_rcu_2_arg_vmalloc_test", kvfree_rcu_2_arg_vmalloc_test },
> +	{ "vm_map_ram_test", vm_map_ram_test },
>  	/* Add a new test case here. */
>  };
>
> --
> 2.30.2
>