When reviewing <https://lore.kernel.org/r/20221029084715.3669204-1-tongtiangen@xxxxxxxxxx> I noticed that the arch-specific VM_FAULT flags used by arm and s390 alias with VM_FAULT_HINDEX_MASK. I'm not sure if it's possible to manifest this as a bug, but it certainly seems fragile. I'm including that original patch this time in the hope that makes it easier for folks to review. There were some boring conflicts so I figured I'd rebase rather than pinging again. Changes since v1 <20221203030356.3917-1-palmer@xxxxxxxxxxxx>: * Add the original patch, and reorder the RISC-V stuff first. * Rebased on v6.3-rc2 * Moved the comment about VM_FAULT_ARCH_* to the patch that adds those, rather than the patch that adds 0s.