linux-kernel - Re: [PATCH 1/2] percpu: km: remove SMP check

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Message-ID: <20190225151330.GA49611@dennisz-mbp.dhcp.thefacebook.com>
Date:   Mon, 25 Feb 2019 10:13:30 -0500
From:   Dennis Zhou <dennis@...nel.org>
To:     Peng Fan <peng.fan@....com>
Cc:     "dennis@...nel.org" <dennis@...nel.org>,
        "tj@...nel.org" <tj@...nel.org>, "cl@...ux.com" <cl@...ux.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "van.freenix@...il.com" <van.freenix@...il.com>
Subject: Re: [PATCH 1/2] percpu: km: remove SMP check

On Sun, Feb 24, 2019 at 01:13:43PM +0000, Peng Fan wrote:
> percpu-km could only be selected by NEED_PER_CPU_KM which
> depends on !SMP, so CONFIG_SMP will be false when choose percpu-km.
> 
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  mm/percpu-km.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/percpu-km.c b/mm/percpu-km.c
> index 0f643dc2dc65..66e5598be876 100644
> --- a/mm/percpu-km.c
> +++ b/mm/percpu-km.c
> @@ -27,7 +27,7 @@
>   *   chunk size is not aligned.  percpu-km code will whine about it.
>   */
>  
> -#if defined(CONFIG_SMP) && defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
> +#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
>  #error "contiguous percpu allocation is incompatible with paged first chunk"
>  #endif
>  
> -- 
> 2.16.4
> 

Hi,

I think keeping CONFIG_SMP makes this easier to remember dependencies
rather than having to dig into the config. So this is a NACK from me.

Thanks,
Dennis