On 04/09/2025 19:28, Lorenzo Stoakes wrote:

Hi Kevin,

This is causing a build failure:

In file included from ./include/linux/mm.h:31,
                 from mm/userfaultfd.c:8:
mm/userfaultfd.c: In function ‘move_present_ptes’:
./include/linux/pgtable.h:247:41: error: statement with no effect [-Werror=unused-value]
  247 | #define arch_enter_lazy_mmu_mode()      (LAZY_MMU_DEFAULT)
      |                                         ^
mm/userfaultfd.c:1103:9: note: in expansion of macro ‘arch_enter_lazy_mmu_mode’
 1103 |         arch_enter_lazy_mmu_mode();
      |         ^~~~~~~~~~~~~~~~~~~~~~~~
./include/linux/pgtable.h:248:54: error: expected expression before ‘)’ token
  248 | #define arch_leave_lazy_mmu_mode(state) ((void)(state))
      |                                                      ^
mm/userfaultfd.c:1141:9: note: in expansion of macro ‘arch_leave_lazy_mmu_mode’
 1141 |         arch_leave_lazy_mmu_mode();
      |         ^~~~~~~~~~~~~~~~~~~~~~~~

It seems you haven't carefully checked call sites here, please do very
carefully recheck these - I see Yeoreum reported a mising kasan case, so I
suggest you just aggressively grep this + make sure you've covered all
bases :)

I did check all call sites pretty carefully and of course build-tested,
but my series is based on v6.17-rc4 - just like the calls Yeoreum
mentioned, the issue is that those calls are in mm-stable but not in
mainline :/ I suppose I should post a v2 rebased on mm-stable ASAP then?

- Kevin