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Subject: Re: [PATCH v2] mm/gup_test: GUP_TEST depends on DEBUG_FS
To:     Barry Song <song.bao.hua@hisilicon.com>,
        <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
        <linux-kernel@vger.kernel.org>
CC:     <linuxarm@huawei.com>, Ralph Campbell <rcampbell@nvidia.com>,
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        John Garry <john.garry@huawei.com>
References: <20201108083732.15336-1-song.bao.hua@hisilicon.com>
From:   John Hubbard <jhubbard@nvidia.com>
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Date:   Sun, 8 Nov 2020 23:45:57 -0800
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On 11/8/20 12:37 AM, Barry Song wrote:
> Without DEBUG_FS, all the code in gup_test becomes meaningless. For sure
> kernel provides debugfs stub while DEBUG_FS is disabled, but the point
> here is that GUP_TEST can do nothing without DEBUG_FS.
> 
> Cc: John Hubbard <jhubbard@nvidia.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: Randy Dunlap <rdunlap@infradead.org>
> Suggested-by: John Garry <john.garry@huawei.com>
> Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
> ---
>   -v2:
>   add comment as a prompt to users as commented by John and Randy, thanks!
> 
>   mm/Kconfig | 4 ++++
>   1 file changed, 4 insertions(+)

Thanks for suffering through a lot of discussion about this!

Reviewed-by: John Hubbard <jhubbard@nvidia.com>


thanks,
-- 
John Hubbard
NVIDIA

> 
> diff --git a/mm/Kconfig b/mm/Kconfig
> index 01b0ae0cd9d3..a7ff0d31afd5 100644
> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -836,6 +836,7 @@ config PERCPU_STATS
>   
>   config GUP_TEST
>   	bool "Enable infrastructure for get_user_pages()-related unit tests"
> +	depends on DEBUG_FS
>   	help
>   	  Provides /sys/kernel/debug/gup_test, which in turn provides a way
>   	  to make ioctl calls that can launch kernel-based unit tests for
> @@ -853,6 +854,9 @@ config GUP_TEST
>   
>   	  See tools/testing/selftests/vm/gup_test.c
>   
> +comment "GUP_TEST needs to have DEBUG_FS enabled"
> +	depends on !GUP_TEST && !DEBUG_FS
> +
>   config GUP_GET_PTE_LOW_HIGH
>   	bool
>   
>