linux-kernel - Re: [PATCH] kernel: sysctl: make drop

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Date:   Mon, 4 Nov 2019 11:37:34 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Johannes Weiner <hannes@...xchg.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        kernel-team@...com
Subject: Re: [PATCH] kernel: sysctl: make drop_caches write-only

On 31.10.19 23:16, Johannes Weiner wrote:
> Currently, the drop_caches proc file and sysctl read back the last
> value written, suggesting this is somehow a stateful setting instead
> of a one-time command. Make it write-only, like e.g. compact_memory.
> 
> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> ---
>   kernel/sysctl.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/sysctl.c b/kernel/sysctl.c
> index 31ece1120aa4..50373984a5e2 100644
> --- a/kernel/sysctl.c
> +++ b/kernel/sysctl.c
> @@ -1474,7 +1474,7 @@ static struct ctl_table vm_table[] = {
>   		.procname	= "drop_caches",
>   		.data		= &sysctl_drop_caches,
>   		.maxlen		= sizeof(int),
> -		.mode		= 0644,
> +		.mode		= 0200,
>   		.proc_handler	= drop_caches_sysctl_handler,
>   		.extra1		= SYSCTL_ONE,
>   		.extra2		= &four,
> 

Makes perfect sense to me (and we might notice while in next/master if 
this breaks something, hopefully)

Acked-by: David Hildenbrand <david@...hat.com>

-- 

Thanks,

David / dhildenb