Re: [PATCH] sysctl: Fix division by zero in percpu_pagelist_fraction handler

[Oleg Drokin]

Hello!

On Jun 2, 2014, at 11:57 PM, David Rientjes wrote:
> I'm pretty sure we want to allow users to restore the kernel default 
> behavior if they've already written to this file and now want to change it 
> back.
> 
> What do you think about doing it like this instead?
> ---
> Documentation/sysctl/vm.txt |  3 ++-
> kernel/sysctl.c             |  3 +--
> mm/page_alloc.c             | 20 ++++++++++++--------
> 3 files changed, 15 insertions(+), 11 deletions(-)
> 
> diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
> --- a/Documentation/sysctl/vm.txt
> +++ b/Documentation/sysctl/vm.txt
> @@ -702,7 +702,8 @@ The batch value of each per cpu pagelist is also updated as a result.  It is
> set to pcp->high/4.  The upper limit of batch is (PAGE_SHIFT * 8)
> 
> The initial value is zero.  Kernel does not use this value at boot time to set
> -the high water marks for each per cpu page list.
> +the high water marks for each per cpu page list.  If the user writes '0' to this
> +sysctl, it will revert to this default behavior.

I think this is probably a better idea indeed.
Always good to let users return back to defaults too.

Thanks!

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