Hello, Aneesh! Yesterday evening's next-20210622 testing gave me the following kernel-build error: ld: mm/mremap.o: in function `move_huge_pud': /home/git/linux-next/mm/mremap.c:372: undefined reference to `__compiletime_assert_395' Bisection landed on this commit: 257121c5aabe ("mm/mremap: convert huge PUD move to separate helper") I have no idea how this commit relates to that error message, but reverting this commit on top of next-20210622 really does get rid of the problem. The following reproducer provokes this error: tools/testing/selftests/rcutorture/bin/kvm.sh --allcpus --torture lock --configs LOCK07 --build-only --kconfig "CONFIG_DEBUG_LOCK_ALLOC=y CONFIG_PROVE_LOCKING=y" --kmake-arg "CC=clang-11" Run the above command in the top-level directory of your -next source tree, and using this compiler: $ clang-11 -v Ubuntu clang version 11.1.0-++20210428103817+1fdec59bffc1-1~exp1~20210428204431.166 Target: x86_64-pc-linux-gnu Thoughts? Thanx, Paul