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. cheers
