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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Wed, 12 Jul 2023 09:51:52 -0700
Message-ID: <CAHk-=whA9rmvNfo=8iKmtimayiA2Aus4XvPwcDrA53G2rfGP0w@mail.gmail.com>
Subject: Re: Fwd: Need NVME QUIRK BOGUS for SAMSUNG MZ1WV480HCGL-000MV
 (Samsung SM-953 Datacenter SSD)
To:     Christoph Hellwig <hch@lst.de>
Cc:     Linux regressions mailing list <regressions@lists.linux.dev>,
        Pankaj Raghav <p.raghav@samsung.com>,
        Keith Busch <kbusch@kernel.org>,
        Bagas Sanjaya <bagasdotme@gmail.com>,
        Jens Axboe <axboe@kernel.dk>, Sagi Grimberg <sagi@grimberg.me>,
        "Clemens S." <cspringsguth@gmail.com>,
        Martin Belanger <martin.belanger@dell.com>,
        Chaitanya Kulkarni <kch@nvidia.com>,
        John Meneghini <jmeneghi@redhat.com>,
        Hannes Reinecke <hare@suse.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux NVMe <linux-nvme@lists.infradead.org>,
        Kanchan Joshi <joshi.k@samsung.com>,
        Javier Gonzalez <javier.gonz@samsung.com>,
        =?UTF-8?B?67CV7KeE7ZmY?= <jh.i.park@samsung.com>
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On Wed, 12 Jul 2023 at 09:45, Christoph Hellwig <hch@lst.de> wrote:
>
> On Tue, Jul 11, 2023 at 09:47:00AM -0700, Linus Torvalds wrote:
>
> > and we have NEVER EVER seen devices with reliably unique IDs. Really.
>
> Sorry, but that's bullshit.

Christoph, you are *literally* involved in a discussion where this is the case.

What you call "bullshit" is what everybody else here calls REALITY.

The fact that *some* devices have serial numbers in no way implies
that all of them do.

And if you think that they all do, you are the problem. Literally in this case.

So you had better really internalize this "there are no reliable
serial numbers in general". Because it's simply a FACT.

> Well, let's try something like this (co-developed with Sagi) that
> allows it for non-multipath PCIe devices, which covers the quirks
> we've added so far, but also add a big fat warning, because we know
> people rely on the /dev/disk/by-id/ links.  Probably not on these
> devices, but who knows.

Looks sane to me.

          Linus