On Wed, 26 May 2021 11:43:35 +0200 Thomas Bogendoerfer [off-list ref] wrote:

This reverts commit f685a533a7fab35c5d069dcd663f59c8e4171a75.

MIPS cache flush logic needs to know whether the mapping was already
established to decide how to flush caches. This is done by checking the
valid bit in the PTE. The commit above breaks this logic by setting
the valid in the PTE in new mappings, which causes kernel crashes.

Thanks.  I added

Fixes: f685a533a7f ("MIPS: make userspace mapping young by default")
Cc: <redacted>