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Date: Mon, 7 Jul 2025 08:24:28 -0600
From: Keith Busch <kbusch@kernel.org>
To: Christoph Hellwig <hch@lst.de>
Cc: Alan Adamson <alan.adamson@oracle.com>,
	John Garry <john.g.garry@oracle.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	Jens Axboe <axboe@kernel.dk>, linux-nvme@lists.infradead.org,
	linux-block@vger.kernel.org
Subject: Re: What should we do about the nvme atomics mess?
Message-ID: <aGvYnMciN_IZC65Z@kbusch-mbp>
References: <20250707141834.GA30198@lst.de>
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In-Reply-To: <20250707141834.GA30198@lst.de>

On Mon, Jul 07, 2025 at 04:18:34PM +0200, Christoph Hellwig wrote:
> We could:
> 
>  I.	 revert the check and the subsequent fixup.  If you really want
>          to use the nvme atomics you already better pray a lot anyway
> 	 due to issue 1)
>  II.	 limit the check to multi-controller subsystems
>  III.	 don't allow atomics on controllers that only report AWUPF and
>  	 limit support to controllers that support that more sanely
> 	 defined NAWUPF
> 
> I guess for 6.16 we are limited to I. to bring us back to the previous
> state, but I have a really bad gut feeling about it given the really
> bad spec language and a lot of low quality NVMe implementations we're
> seeing these days.

I like option III. The controler scoped atomic size is broken for all
the reasons you mentioned, so I vote we not bother trying to make sense
of it.