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Message-Id: <20210405193920.46d3792200ad05f4a7c66829@linux-foundation.org>
Date: Mon, 5 Apr 2021 19:39:20 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Uladzislau Rezki <urezki@...il.com>
Cc: linux-mm@...ck.org, LKML <linux-kernel@...r.kernel.org>,
Hillf Danton <hdanton@...a.com>,
Michal Hocko <mhocko@...e.com>,
Matthew Wilcox <willy@...radead.org>,
Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH-next 2/5] lib/test_vmalloc.c: add a new 'nr_threads'
parameter
On Sat, 3 Apr 2021 14:31:43 +0200 Uladzislau Rezki <urezki@...il.com> wrote:
> >
> > We may need to replaced that kcalloc() with kmvalloc() though...
> >
> Yep. If we limit to USHRT_MAX, the maximum amount of memory for
> internal data would be ~12MB. Something like below:
>
> diff --git a/lib/test_vmalloc.c b/lib/test_vmalloc.c
> index d337985e4c5e..a5103e3461bf 100644
> --- a/lib/test_vmalloc.c
> +++ b/lib/test_vmalloc.c
> @@ -24,7 +24,7 @@
> MODULE_PARM_DESC(name, msg) \
>
> __param(int, nr_threads, 0,
> - "Number of workers to perform tests(min: 1 max: 1024)");
> + "Number of workers to perform tests(min: 1 max: 65536)");
>
> __param(bool, sequential_test_order, false,
> "Use sequential stress tests order");
> @@ -469,13 +469,13 @@ init_test_configurtion(void)
> {
> /*
> * A maximum number of workers is defined as hard-coded
> - * value and set to 1024. We add such gap just in case
> + * value and set to 65536. We add such gap just in case
> * and for potential heavy stressing.
> */
> - nr_threads = clamp(nr_threads, 1, 1024);
> + nr_threads = clamp(nr_threads, 1, 65536);
>
> /* Allocate the space for test instances. */
> - tdriver = kcalloc(nr_threads, sizeof(*tdriver), GFP_KERNEL);
> + tdriver = kvcalloc(nr_threads, sizeof(*tdriver), GFP_KERNEL);
> if (tdriver == NULL)
> return -1;
>
> @@ -555,7 +555,7 @@ static void do_concurrent_test(void)
> i, t->stop - t->start);
> }
>
> - kfree(tdriver);
> + kvfree(tdriver);
> }
>
> static int vmalloc_test_init(void)
>
> Does it sound reasonable for you?
I think so. It's a test thing so let's give testers more flexibility,
remembering that they don't need as much protection from their own
mistakes.
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