Messages in this thread | | | Date | Tue, 17 Nov 2020 19:45:28 -0500 | From | Sasha Levin <> | Subject | Re: Same problem for 4.14.y and a concern: Re: [PATCH 4.19 056/191] powerpc: select ARCH_WANT_IRQS_OFF_ACTIVATE_MM |
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On Tue, Nov 17, 2020 at 10:51:16AM -0800, Kamal Mostafa wrote: >On Tue, Nov 3, 2020 at 4:22 PM Michael Ellerman <mpe@ellerman.id.au> wrote: > >> Greg Kroah-Hartman <gregkh@linuxfoundation.org> writes: >> > From: Nicholas Piggin <npiggin@gmail.com> >> > >> > [ 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@gmail.com> >> > Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> >> > Link: >> https://lore.kernel.org/r/20200914045219.3736466-3-npiggin@gmail.com >> > Signed-off-by: Sasha Levin <sashal@kernel.org> >> > --- >> > 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. >> >> cheers >> > >Hi- > >This glitch has made its way into 4.14.y ... > [4.14.y] c2bca8712a19 powerpc: select ARCH_WANT_IRQS_OFF_ACTIVATE_MM >But 4.14.y does not carry the prereq that introduces that config.
I'll queue up the 4.19 backport for 4.14 too, thanks!
-- Thanks, Sasha
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