15.1/errata: add issue: NFSv4.1/4.2 client panic during server recovery

[vladlen]

Summary

Add an erratum describing a problem where the NFSv4.1 or NFSv4.2 client
may cause a kernel panic when the NFS server becomes unresponsive or
reboots. The system automatically reboots after the panic.

The erratum also documents a workaround: avoid using "soft" or "intr"
mount options with NFSv4.1/4.2 mounts, or downgrade to NFSv3 until a
patched version is available.

This is the issue from the list Won't fix
https://wiki.freebsd.org/action/diff/Releng/15.1ISSUES?action=diff&rev1=62&rev2=63

[vladlen]

website/content/en/releases/15.1R/errata.adoc

66–68

new proposed text

1.  **man:nfs[4]** client may panic when using `soft` or `intr` mount options
with NFSv4.1 or NFSv4.2. The panic occurs when the NFS server determines that
the client's session state is invalid (for example, after the server reboots
or experiences a network disruption), triggering a recovery attempt that
exposes a bug in the session handling code. +
**Workaround**: Avoid using `soft` or `intr` mount options with NFSv4.1/4.2
mounts. Use NFSv3 instead if these mount options are required.
The use of these options with NFSv4.1/4.2 is already discouraged in the
man:mount_nfs[8] manual page. +
**State**: fixed in main - https://bugs.freebsd.org/294925

[ziaee]

website/content/en/releases/15.1R/errata.adoc

66–68

I think what you have in the diff is really perfect. The proposed text in this comment is too wordy. The additional details are inappropriate for this type of docs; it is provided in the bug link for those who want to dig in.

The docs produced by re@ are "requirements docs". This is the most simplified and concise type of documentation. It needs to tell a target audience of every single person who might install freebsd only exactly what they need to know. If the lowest common denominator doesn't understand, this is our fault. Which is wildly different than say, a reference manual on a system call. People who don't even understand what that last sentence means are expected to read and understand this doc.

This is considerably different from say, website (marketing docs), handbook (user docs), or manpages (reference docs). Internet says there are 15 different fundamental types of docs for software. I don't know about that, but I do know a bit about our docs ;P