Fwd: Compile Error fs/nfsd/nfs4state.o - clamp() low limit slotsize greater than high limit total_avail/scale_factor

[Chuck Lever <cel@kernel.org>]

FYI

https://bugzilla.kernel.org/show_bug.cgi?id=220745


-------- Forwarded Message --------
Subject: Re: Compile Error fs/nfsd/nfs4state.o - clamp() low limit
slotsize greater than high limit total_avail/scale_factor
Date: Thu, 06 Nov 2025 07:29:25 -0500
From: Jeff Layton <jlayton@kernel.org>
To: Mike-SPC via Bugspray Bot <bugbot@kernel.org>, cel@kernel.org,
neilb@ownmail.net, trondmy@kernel.org, linux-nfs@vger.kernel.org,
anna@kernel.org, neilb@brown.name

On Thu, 2025-11-06 at 11:30 +0000, Mike-SPC via Bugspray Bot wrote:
> Mike-SPC writes via Kernel.org Bugzilla:
> 
> (In reply to Bugspray Bot from comment #5)
> > Chuck Lever <cel@kernel.org> replies to comment #4:
> > 
> > On 11/5/25 7:25 AM, Mike-SPC via Bugspray Bot wrote:
> > > Mike-SPC writes via Kernel.org Bugzilla:
> > > 
> > > > Have you found a 6.1.y kernel for which the build doesn't fail?
> > > 
> > > Yes. Compiling Version 6.1.155 works without problems.
> > > Versions >= 6.1.156 aren't.
> > 
> > My analysis yesterday suggests that, because the nfs4state.c code hasn't
> > changed, it's probably something elsewhere that introduced this problem.
> > As we can't reproduce the issue, can you use "git bisect" between
> > v6.1.155 and v6.1.156 to find the culprit commit?
> > 
> > (via https://msgid.link/ab235dbe-7949-4208-a21a-2cdd50347152@kernel.org)
> 
> 
> Yes, your analysis is right (thanks for it).
> After some investigation, the issue appears to be caused by changes introduced in
> include/linux/minmax.h.
> 
> I verified this by replacing minmax.h in 6.1.156 with the version from 6.1.155,
> and the kernel then compiles successfully.
> 
> The relevant section in the 6.1.156 changelog (https://cdn.kernel.org/pub/linux/kernel/v6.x/ChangeLog-6.1.156) shows several modifications to minmax.h (notably around __clamp_once() and the use of
> BUILD_BUG_ON_MSG(statically_true(ulo > uhi), ...)), which seem to trigger a compile-time assertion when building NFSD.
> 
> Replacing the updated header with the previous one resolves the issue, so this appears
> to be a regression introduced by the new clamp() logic.
> 
> Could you please advise who is the right person or mailing list to report this issue to
> (minmax.h maintainers, kernel core, or stable tree)?
> 

I'd let all 3 know, and I'd include the author of the patches that you
suspect are the problem. They'll probably want to revise the one that's
a problem.

Cheers,
-- 
Jeff Layton <jlayton@kernel.org>