On Wed, 20 Oct 2021, Eric W. Biederman wrote:

When an instruction to save or restore a register from the stack fails
in _save_fp_context or _restore_fp_context return with -EFAULT.  This
change was made to r2300_fpu.S[1] but it looks like it got lost with
the introduction of EX2[2].  This is also what the other implementation
of _save_fp_context and _restore_fp_context in r4k_fpu.S does, and
what is needed for the callers to be able to handle the error.

 Umm, right, good catch, thanks!  I think this ought to be backported.

Acked-by: Maciej W. Rozycki <macro@orcam.me.uk>

  Maciej