Re: [PATCH] lib/test_vmalloc.c: Minor fixes to test_vmalloc.c

[Andrew Morton]

On Mon,  1 Dec 2025 13:18:48 -0500 Audra Mitchell <audra@xxxxxxxxxx> wrote:

> If PAGE_SIZE is larger than 4k and if you have a system with a
> large number of CPUs, this test can require a very large amount
> of memory leading to oom-killer firing. Given the type of allocation,
> the kernel won't have anything to kill, causing the system to
> stall. Add a parameter to the test_vmalloc driver to represent the
> number of times a percpu object will be allocated. Calculate this
> in test_vmalloc.sh to be 90% of available memory or the current
> default of 35000, whichever is smaller.
> 
> ...
>
> --- a/lib/test_vmalloc.c
> +++ b/lib/test_vmalloc.c
> @@ -57,6 +57,9 @@ __param(int, run_test_mask, 7,
>  		/* Add a new test case description here. */
>  );
>  
> +__param(int, nr_pcpu_objects, 35000,
> +	"Number of pcpu objects to allocate for pcpu_alloc_test");
> +
>  /*
>   * This is for synchronization of setup phase.
>   */
> @@ -292,24 +295,24 @@ pcpu_alloc_test(void)
>  	size_t size, align;
>  	int i;
>  
> -	pcpu = vmalloc(sizeof(void __percpu *) * 35000);
> +	pcpu = vmalloc(sizeof(void __percpu *) * nr_pcpu_objects);

Could have used vmalloc_array() here.  Otherwise lgtm, thanks.