linux-kernel - Re: [PATCH v5 3/7] cxl/region: Skip decoder reset on detach for autodiscovered regions

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Message-ID: <69794c2512bfc_1d3310087@dwillia2-mobl4.notmuch>
Date: Tue, 27 Jan 2026 15:37:09 -0800
From: <dan.j.williams@...el.com>
To: "Koralahalli Channabasappa, Smita" <skoralah@....com>, Jonathan Cameron
	<jonathan.cameron@...wei.com>, Smita Koralahalli
	<Smita.KoralahalliChannabasappa@....com>
CC: <linux-cxl@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<nvdimm@...ts.linux.dev>, <linux-fsdevel@...r.kernel.org>,
	<linux-pm@...r.kernel.org>, Ard Biesheuvel <ardb@...nel.org>, "Alison
 Schofield" <alison.schofield@...el.com>, Vishal Verma
	<vishal.l.verma@...el.com>, Ira Weiny <ira.weiny@...el.com>, Dan Williams
	<dan.j.williams@...el.com>, Yazen Ghannam <yazen.ghannam@....com>, Dave Jiang
	<dave.jiang@...el.com>, Davidlohr Bueso <dave@...olabs.net>, Matthew Wilcox
	<willy@...radead.org>, Jan Kara <jack@...e.cz>, "Rafael J . Wysocki"
	<rafael@...nel.org>, Len Brown <len.brown@...el.com>, Pavel Machek
	<pavel@...nel.org>, Li Ming <ming.li@...omail.com>, Jeff Johnson
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	Yao Xingtao <yaoxt.fnst@...itsu.com>, Peter Zijlstra <peterz@...radead.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Nathan Fontenot
	<nathan.fontenot@....com>, Terry Bowman <terry.bowman@....com>, "Robert
 Richter" <rrichter@....com>, Benjamin Cheatham <benjamin.cheatham@....com>,
	Zhijian Li <lizhijian@...itsu.com>, Borislav Petkov <bp@...en8.de>, "Tomasz
 Wolski" <tomasz.wolski@...itsu.com>
Subject: Re: [PATCH v5 3/7] cxl/region: Skip decoder reset on detach for
 autodiscovered regions

Koralahalli Channabasappa, Smita wrote:
[..]
> I’m re reading Dan’s note here:
> https://lore.kernel.org/all/6930dacd6510f_198110020@dwillia2-mobl4.notmuch/
> 
> Specifically this part:
> "If the administrator actually wants to destroy and reclaim that
> physical address space then they need to forcefully de-commit that
> auto-assembled region via the @commit sysfs attribute. So that means
> commit_store() needs to clear CXL_REGION_F_AUTO to get the decoder reset
> to happen."
> 
> Today the sysfs commit=0 path inside commit_store() resets decoders 
> without the AUTO check whereas the detach path now skips the reset when 
> CXL_REGION_F_AUTO is set.
> 
> I think the same rationale should apply to the sysfs de-commit path as 
> well? I’m trying to understand the implications of not guarding the 
> reset with AUTO in commit_store().

Linux tends to give the administrator the ability to know better than the
kernel. So if the root forcefully decommits the region, root gets to
keep the pieces.