linux-kernel - Re: [PATCH] doc,cgroup-v2: memory.max is reported in multiples of page size

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Message-ID: <Z_fOenjfni55JsbV@linux.ibm.com>
Date: Thu, 10 Apr 2025 19:28:18 +0530
From: Vishal Chourasia <vishalc@...ux.ibm.com>
To: Michal Koutný <mkoutny@...e.com>
Cc: tj@...nel.org, hannes@...xchg.org, corbet@....net, cgroups@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] doc,cgroup-v2: memory.max is reported in multiples of
 page size

On Thu, Apr 10, 2025 at 03:47:06PM +0200, Michal Koutný wrote:
> Hello.
> 
> On Thu, Apr 10, 2025 at 07:04:40PM +0530, Vishal Chourasia <vishalc@...ux.ibm.com> wrote:
> > Update documentation for memory.max to clarify that the reported value
> > is in multiples of the system page_size. The following example
> > demonstrates this behavior:
> 
> This applies to any of page_counter-based attribute, not only
> memory.max.
> 
Yes. This is already documented, and I missed it.

>From Documentation/admin-api/cgroup-v2.rst:
...
Memory Interface Files
~~~~~~~~~~~~~~~~~~~~~~

All memory amounts are in bytes.  If a value which is not aligned to
PAGE_SIZE is written, the value may be rounded up to the closest
PAGE_SIZE multiple when read back.
...
> > --- a/Documentation/admin-guide/cgroup-v2.rst
> > +++ b/Documentation/admin-guide/cgroup-v2.rst
> > @@ -1316,6 +1316,9 @@ PAGE_SIZE multiple when read back.
> >  	Caller could retry them differently, return into userspace
> >  	as -ENOMEM or silently ignore in cases like disk readahead.
> >  
> > +        Note that the value set for memory.max is reported in units
> > +        corresponding to the system's page size.
> > +
> 
> There seems to be mismatch in whitespace to surrounding text.
> 
> Also the wording would be more precise if it referred to 'multiples',
> not 'units' (units are simply bytes).
> 
> Michal
>
Got it. But, it seems this patch is redundant. So, I won't be sending
another version.

Thanks,
Vishal