Heads-up from Linus -- potential bisection trainwreck: "A note on the 5.12-rc1 tag"

[Bengt Richter <bokr@bokr.com>]

Hi,

Not so usual to be switching rc kernels for guix I suppose, but
this looked worth mentioning anyway:

LWN archive link [1]

[1]https://lwn.net/ml/linux-kernel/CAHk-=wjnzdLSP3oDxhf9eMTYo7GF-QjaNLBUH1Zk3c4A7X75YA@mail.gmail.com/

In case of link problem, a couple of extractions:
--8<---------------cut here---------------start------------->8---
From: 	 	Linus Torvalds <torvalds-AT-linux-foundation.org>
To: 	 	Linux Kernel Mailing List <linux-kernel-AT-vger.kernel.org>
Subject: 	 	A note on the 5.12-rc1 tag
Date: 	 	Wed, 03 Mar 2021 12:53:18 -0800
Message-ID: 	 	<CAHk-=wjnzdLSP3oDxhf9eMTYo7GF-QjaNLBUH1Zk3c4A7X75YA@mail.gmail.com>

Hey peeps - some of you may have already noticed that in my public git
tree, the "v5.12-rc1" tag has magically been renamed to
"v5.12-rc1-dontuse". It's still the same object, it still says
"v5.12-rc1" internally, and it is still is signed by me, but the
user-visible name of the tag has changed.

The reason is fairly straightforward: this merge window, we had a very
innocuous code cleanup and simplification that raised no red flags at
all, but had a subtle and very nasty bug in it: swap files stopped
working right.  And they stopped working in a particularly bad way:
the offset of the start of the swap file was lost.

Swapping still happened, but it happened to the wrong part of the
filesystem, with the obvious catastrophic end results.

[ -- snip discussion why all will not be hit -- ]

But I want everybody to be aware of because _if_ it bites you, it
bites you hard, and you can end up with a filesystem that is
essentially overwritten by random swap data. This is what we in the
industry call "double ungood".

--8<---------------cut here---------------end--------------->8---

-- 
Regards,
Bengt Richter