I did another test, with the commits 2e6871a632a99d9b9e2ce3a7847acabe99e5a26e
and bc2846c7ab029f0660fef1774c6d02a1ec021aaa from the upstream Kernel as
requested by Jiri:
> 2e6871a632a99d9b9e2ce3a7847acabe99e5a26e: fail
> bc2846c7ab029f0660fef1774c6d02a1ec021aaa: ok
This confirms the result of the bisection that
2e6871a632a99d9b9e2ce3a7847acabe99e5a26e is (likely) the culprit.
I will also add the dmesg for both commits here.