Hi Randy,

On Mon, 20 Jul 2020 09:56:08 -0700 Randy Dunlap <rdunlap@infradead.org> wrote:
>
> on x86_64:
> 
>   CC [M]  arch/x86/kvm/mmu/page_track.o
> In file included from ../include/linux/pid.h:5:0,
>                  from ../include/linux/sched.h:14,
>                  from ../include/linux/kvm_host.h:12,
>                  from ../arch/x86/kvm/mmu/page_track.c:14:
> ../arch/x86/kvm/mmu/page_track.c: In function ‘kvm_page_track_write’:
> ../include/linux/rculist.h:727:30: error: left-hand operand of comma expression has no effect [-Werror=unused-value]
>   for (__list_check_srcu(cond),     \
>                               ^
> ../arch/x86/kvm/mmu/page_track.c:232:2: note: in expansion of macro ‘hlist_for_each_entry_srcu’
>   hlist_for_each_entry_srcu(n, &head->track_notifier_list, node,
>   ^~~~~~~~~~~~~~~~~~~~~~~~~
> ../arch/x86/kvm/mmu/page_track.c: In function ‘kvm_page_track_flush_slot’:
> ../include/linux/rculist.h:727:30: error: left-hand operand of comma expression has no effect [-Werror=unused-value]
>   for (__list_check_srcu(cond),     \
>                               ^
> ../arch/x86/kvm/mmu/page_track.c:258:2: note: in expansion of macro ‘hlist_for_each_entry_srcu’
>   hlist_for_each_entry_srcu(n, &head->track_notifier_list, node,
>   ^~~~~~~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors

Caused by commit

  bd4444c47de9 ("rculist : Introduce list/hlist_for_each_entry_srcu() macros")

presumably with CONFIG_PROVE_RCU_LIST not set.

-- 
Cheers,
Stephen Rothwell