On Fri, Apr 29, 2016 at 02:07:54PM -0700, Yang Shi wrote:

Inspired by the counterpart of powerpc [1], which shows there is no negative
effect on code generation from enabling STRICT_MM_TYPECHECKS with a modern
compiler.

And, Arnd's comment [2] about that patch says STRICT_MM_TYPECHECKS could
be default as long as the architecture can pass structures in registers as
function arguments. ARM64 can do it as long as the size of structure <= 16
bytes. All the page table value types are u64 on ARM64.

The below disassembly demonstrates it, entry is pte_t type:

            entry = arch_make_huge_pte(entry, vma, page, writable);
   0xffff00000826fc38 <+80>:    and     x0, x0, #0xfffffffffffffffd
   0xffff00000826fc3c <+84>:    mov     w3, w21
   0xffff00000826fc40 <+88>:    mov     x2, x20
   0xffff00000826fc44 <+92>:    mov     x1, x19
   0xffff00000826fc48 <+96>:    orr     x0, x0, #0x400
   0xffff00000826fc4c <+100>:   bl      0xffff00000809bcc0 <arch_make_huge_pte>

[1] http://www.spinics.net/lists/linux-mm/msg105951.html
[2] http://www.spinics.net/lists/linux-mm/msg105969.html

Signed-off-by: Yang Shi <redacted>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Ard Biesheuvel <redacted>

I'm fine with this change. If Will is still cherry-picking patches for
4.7:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>