On 4 January 2017 at 13:28, Will Deacon <will.deacon@xxxxxxx> wrote: > On Wed, Dec 14, 2016 at 09:11:47AM +0000, Ard Biesheuvel wrote: >> The NUMA code may get confused by the presence of NOMAP regions within >> zones, resulting in spurious BUG() checks where the node id deviates >> from the containing zone's node id. >> >> Since the kernel has no business reasoning about node ids of pages it >> does not own in the first place, enable CONFIG_HOLES_IN_ZONE to ensure >> that such pages are disregarded. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> >> --- >> arch/arm64/Kconfig | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig >> index 111742126897..0472afe64d55 100644 >> --- a/arch/arm64/Kconfig >> +++ b/arch/arm64/Kconfig >> @@ -614,6 +614,10 @@ config NEED_PER_CPU_EMBED_FIRST_CHUNK >> def_bool y >> depends on NUMA >> >> +config HOLES_IN_ZONE >> + def_bool y >> + depends on NUMA >> + >> source kernel/Kconfig.preempt >> source kernel/Kconfig.hz > > I'm happy to apply this, but I'll hold off until the first patch is queued > somewhere, since this doesn't help without the VM_BUG_ON being moved. > > Alternatively, I can queue both if somebody from the mm camp acks the > first patch. > Actually, I am not convinced the discussion is finalized. These patches do fix the issue, but Robert also suggested an alternative fix which may be preferable. http://marc.info/?l=linux-arm-kernel&m=148190753510107&w=2 I haven't responded to it yet, due to the holidays, but I'd like to explore that solution a bit further before applying anything, if you don't mind. Thanks, Ard. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>