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Date:   Wed, 6 Dec 2023 07:59:13 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Greg KH <gregkh@linuxfoundation.org>
Cc:     Pasha Tatashin <pasha.tatashin@soleen.com>,
        Sourav Panda <souravpanda@google.com>, corbet@lwn.net,
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Subject: Re: [PATCH v6 0/1] mm: report per-page metadata information
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On Wed, 6 Dec 2023 12:12:10 +0900 Greg KH <gregkh@linuxfoundation.org> wrote:

> On Tue, Dec 05, 2023 at 09:57:36PM -0500, Pasha Tatashin wrote:
> > Hi Greg,
> > 
> > Sourav removed the new field from sys/device../nodeN/meminfo as you
> > requested; however, in nodeN/vmstat fields still get appended, as
> > there is code that displays every item in zone_stat_item,
> > node_stat_item without option to opt-out. I mentioned it to you at
> > LPC.
> 
> Sorry, I thought that was a proc file, not a sysfs file.  Don't grow
> that file please, it should not be that way and adding to it will just
> cause others to also want to add to it and we end up with the whole proc
> file mess...
> 
> > In my IOMMU [1] series, there are also fields that are added to
> > node_stat_item that as result are appended to nodeN/vmstat.
> 
> I missed that, that too shouldn't be done please.
> 
> Again, sysfs is "one value per file" for a reason, don't abuse the fact
> that we missed this abuse of the rules for that file by adding more
> things to it.

I'm afraid that horse has bolted.

hp2:/usr/src/25> wc /sys/devices/system/node/node0/vmstat 
  61  122 1309 /sys/devices/system/node/node0/vmstat

We're never going to unpick this into 61 separate files so adding new
files at this stage is pointless.