Re: [RFC PATCH 05/40] mm: page_alloc: remove watermark boost mechanism

[Rik van Riel <riel@surriel.com>]

On Tue, 2026-05-26 at 07:02 -0700, Usama Arif wrote:
> On Wed, 20 May 2026 10:59:11 -0400 Rik van Riel <riel@surriel.com>
> wrote:
> 
> > @@ -7187,14 +7117,6 @@ static const struct ctl_table
> > page_alloc_sysctl_table[] = {
> >  		.proc_handler	= min_free_kbytes_sysctl_handler,
> >  		.extra1		= SYSCTL_ZERO,
> >  	},
> > -	{
> > -		.procname	= "watermark_boost_factor",
> > -		.data		= &watermark_boost_factor,
> > -		.maxlen		=
> > sizeof(watermark_boost_factor),
> > -		.mode		= 0644,
> > -		.proc_handler	= proc_dointvec_minmax,
> > -		.extra1		= SYSCTL_ZERO,
> > -	},
> 
> 
> This is a userspace-visible removal. Writes to
> /proc/sys/vm/watermark_boost_factor will now return -ENOENT instead
> of being
> accepted, breaking userspace.
> 
> I am not sure whats been done in the past, but we need to add a
> Documentation/ABI/removed/ note explaining what replaces it (SPB
> steering).
> and also maybe keep the sysctl entry as a no-op with warning for a
> few
> cycles before deletion?

I'll just drop this patch for now.

While we no longer need it, and the watermark boosting
can cause a little bit of harm at times, this probably
isn't worth the extra code churn in this series.

-- 
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