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

[Mike-SPC via Bugspray Bot <bugbot@kernel.org>]

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)?

Regards,
Michael

View: https://bugzilla.kernel.org/show_bug.cgi?id=220745#c6
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