On Wed, Nov 04, 2020 at 12:19:45PM +1100, Michael Ellerman wrote: > Michael Ellerman <mpe@xxxxxxxxxxxxxx> writes: > > Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> writes: > >> From: Nicholas Piggin <npiggin@xxxxxxxxx> > >> > >> [ Upstream commit 66acd46080bd9e5ad2be4b0eb1d498d5145d058e ] > >> > >> powerpc uses IPIs in some situations to switch a kernel thread away > >> from a lazy tlb mm, which is subject to the TLB flushing race > >> described in the changelog introducing ARCH_WANT_IRQS_OFF_ACTIVATE_MM. > >> > >> Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx> > >> Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx> > >> Link: https://lore.kernel.org/r/20200914045219.3736466-3-npiggin@xxxxxxxxx > >> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> > >> --- > >> arch/powerpc/Kconfig | 1 + > >> arch/powerpc/include/asm/mmu_context.h | 2 +- > >> 2 files changed, 2 insertions(+), 1 deletion(-) > >> > >> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig > >> index f38d153d25861..0bc53f0e37c0f 100644 > >> --- a/arch/powerpc/Kconfig > >> +++ b/arch/powerpc/Kconfig > >> @@ -152,6 +152,7 @@ config PPC > >> select ARCH_USE_BUILTIN_BSWAP > >> select ARCH_USE_CMPXCHG_LOCKREF if PPC64 > >> select ARCH_WANT_IPC_PARSE_VERSION > >> + select ARCH_WANT_IRQS_OFF_ACTIVATE_MM > > > > This depends on upstream commit: > > > > d53c3dfb23c4 ("mm: fix exec activate_mm vs TLB shootdown and lazy tlb switching race") > > > > > > Which I don't see in 4.19 stable, or in the email thread here. > > > > So this shouldn't be backported to 4.19 unless that commit is also > > backported. > > I just sent you a backport of d53c3dfb23c4 for 4.19. I've taken that at the proper part of this series now, thanks! greg k-h
