linux-kernel - Re: [PATCH] lib/test_meminit.c: Add bulk alloc/free tests

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Date:   Thu, 7 Nov 2019 13:19:50 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Alexander Potapenko <glider@...gle.com>,
        Christoph Lameter <cl@...ux.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Kostya Serebryany <kcc@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Sandeep Patil <sspatil@...roid.com>,
        Jann Horn <jannh@...gle.com>, Marco Elver <elver@...gle.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] lib/test_meminit.c: Add bulk alloc/free tests

On Thu, Nov 07, 2019 at 02:14:47PM -0500, Laura Abbott wrote:
> 
> kmem_cache_alloc_bulk/kmem_cache_free_bulk are used to
> make multiple allocations of the same size to avoid the
> overhead of multiple kmalloc/kfree calls. Extend the kmem_cache
> tests to make some calls to these APIs.
> 
> Signed-off-by: Laura Abbott <labbott@...hat.com>

Thanks! Andrew, can you add this to -mm please?

Reviewed-by: Kees Cook <keescook@...omium.org>

-Kees

> ---
>  lib/test_meminit.c | 20 +++++++++++++++++++-
>  1 file changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/lib/test_meminit.c b/lib/test_meminit.c
> index 9729f271d150..20f330948b92 100644
> --- a/lib/test_meminit.c
> +++ b/lib/test_meminit.c
> @@ -183,6 +183,9 @@ static bool __init check_buf(void *buf, int size, bool want_ctor,
>  	return fail;
>  }
>  
> +#define BULK_SIZE 100
> +static void *bulk_array[BULK_SIZE];
> +
>  /*
>   * Test kmem_cache with given parameters:
>   *  want_ctor - use a constructor;
> @@ -203,9 +206,24 @@ static int __init do_kmem_cache_size(size_t size, bool want_ctor,
>  			      want_rcu ? SLAB_TYPESAFE_BY_RCU : 0,
>  			      want_ctor ? test_ctor : NULL);
>  	for (iter = 0; iter < 10; iter++) {
> +		/* Do a test of bulk allocations */
> +		if (!want_rcu && !want_ctor) {
> +			int ret;
> +
> +			ret = kmem_cache_alloc_bulk(c, alloc_mask, BULK_SIZE, bulk_array);
> +			if (!ret) {
> +				fail = true;
> +			} else {
> +				int i;
> +				for (i = 0; i < ret; i++)
> +					fail |= check_buf(bulk_array[i], size, want_ctor, want_rcu, want_zero);
> +				kmem_cache_free_bulk(c, ret, bulk_array);
> +			}
> +		}
> +
>  		buf = kmem_cache_alloc(c, alloc_mask);
>  		/* Check that buf is zeroed, if it must be. */
> -		fail = check_buf(buf, size, want_ctor, want_rcu, want_zero);
> +		fail |= check_buf(buf, size, want_ctor, want_rcu, want_zero);
>  		fill_with_garbage_skip(buf, size, want_ctor ? CTOR_BYTES : 0);
>  
>  		if (!want_rcu) {
> -- 
> 2.21.0
> 

-- 
Kees Cook