| Message ID | 20191122105253.11375-3-lee.jones@linaro.org |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [4.9,1/8] ARM: 8904/1: skip nomap memblocks while finding the lowmem/highmem boundary | expand |
On Fri, Nov 22, 2019 at 10:52:48AM +0000, Lee Jones wrote: >From: Hari Vyas <hari.vyas@broadcom.com> > >[ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ] > >The bad_mode() handler is called if we encounter an uunknown exception, >with the expectation that the subsequent call to panic() will halt the >system. Unfortunately, if the exception calling bad_mode() is taken from >EL0, then the call to die() can end up killing the current user task and >calling schedule() instead of falling through to panic(). > >Remove the die() call altogether, since we really want to bring down the >machine in this "impossible" case. Should this be in newer LTS kernels too? I don't see it in 4.14. We can't take anything into older kernels if it's not in newer ones - we don't want to break users who update their kernels. -- Thanks, Sasha
On Mon, 25 Nov 2019, Sasha Levin wrote: > On Fri, Nov 22, 2019 at 10:52:48AM +0000, Lee Jones wrote: > > From: Hari Vyas <hari.vyas@broadcom.com> > > > > [ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ] > > > > The bad_mode() handler is called if we encounter an uunknown exception, > > with the expectation that the subsequent call to panic() will halt the > > system. Unfortunately, if the exception calling bad_mode() is taken from > > EL0, then the call to die() can end up killing the current user task and > > calling schedule() instead of falling through to panic(). > > > > Remove the die() call altogether, since we really want to bring down the > > machine in this "impossible" case. > > Should this be in newer LTS kernels too? I don't see it in 4.14. We > can't take anything into older kernels if it's not in newer ones - we > don't want to break users who update their kernels. Only; 3.18, 4.4, 4.9 and 5.3 were studied. I can look at others if it helps. -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
On Mon, Nov 25, 2019 at 02:44:29PM +0000, Lee Jones wrote: > On Mon, 25 Nov 2019, Sasha Levin wrote: > > > On Fri, Nov 22, 2019 at 10:52:48AM +0000, Lee Jones wrote: > > > From: Hari Vyas <hari.vyas@broadcom.com> > > > > > > [ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ] > > > > > > The bad_mode() handler is called if we encounter an uunknown exception, > > > with the expectation that the subsequent call to panic() will halt the > > > system. Unfortunately, if the exception calling bad_mode() is taken from > > > EL0, then the call to die() can end up killing the current user task and > > > calling schedule() instead of falling through to panic(). > > > > > > Remove the die() call altogether, since we really want to bring down the > > > machine in this "impossible" case. > > > > Should this be in newer LTS kernels too? I don't see it in 4.14. We > > can't take anything into older kernels if it's not in newer ones - we > > don't want to break users who update their kernels. > > Only; 3.18, 4.4, 4.9 and 5.3 were studied. > > I can look at others if it helps. You have to look at others, we can't have regressions if people move from one LTS to a newer one. thanks, greg k-h
On Mon, 25 Nov 2019, Greg KH wrote: > On Mon, Nov 25, 2019 at 02:44:29PM +0000, Lee Jones wrote: > > On Mon, 25 Nov 2019, Sasha Levin wrote: > > > > > On Fri, Nov 22, 2019 at 10:52:48AM +0000, Lee Jones wrote: > > > > From: Hari Vyas <hari.vyas@broadcom.com> > > > > > > > > [ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ] > > > > > > > > The bad_mode() handler is called if we encounter an uunknown exception, > > > > with the expectation that the subsequent call to panic() will halt the > > > > system. Unfortunately, if the exception calling bad_mode() is taken from > > > > EL0, then the call to die() can end up killing the current user task and > > > > calling schedule() instead of falling through to panic(). > > > > > > > > Remove the die() call altogether, since we really want to bring down the > > > > machine in this "impossible" case. > > > > > > Should this be in newer LTS kernels too? I don't see it in 4.14. We > > > can't take anything into older kernels if it's not in newer ones - we > > > don't want to break users who update their kernels. > > > > Only; 3.18, 4.4, 4.9 and 5.3 were studied. > > > > I can look at others if it helps. > > You have to look at others, we can't have regressions if people move > from one LTS to a newer one. Sure, I understand. Will do from now on. -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
On Mon, 25 Nov 2019, Lee Jones wrote: > On Mon, 25 Nov 2019, Greg KH wrote: > > > On Mon, Nov 25, 2019 at 02:44:29PM +0000, Lee Jones wrote: > > > On Mon, 25 Nov 2019, Sasha Levin wrote: > > > > > > > On Fri, Nov 22, 2019 at 10:52:48AM +0000, Lee Jones wrote: > > > > > From: Hari Vyas <hari.vyas@broadcom.com> > > > > > > > > > > [ Upstream commit e4ba15debcfd27f60d43da940a58108783bff2a6 ] > > > > > > > > > > The bad_mode() handler is called if we encounter an uunknown exception, > > > > > with the expectation that the subsequent call to panic() will halt the > > > > > system. Unfortunately, if the exception calling bad_mode() is taken from > > > > > EL0, then the call to die() can end up killing the current user task and > > > > > calling schedule() instead of falling through to panic(). > > > > > > > > > > Remove the die() call altogether, since we really want to bring down the > > > > > machine in this "impossible" case. > > > > > > > > Should this be in newer LTS kernels too? I don't see it in 4.14. We > > > > can't take anything into older kernels if it's not in newer ones - we > > > > don't want to break users who update their kernels. > > > > > > Only; 3.18, 4.4, 4.9 and 5.3 were studied. > > > > > > I can look at others if it helps. > > > > You have to look at others, we can't have regressions if people move > > from one LTS to a newer one. Okay, now sent appropriate patches to linux-4.14.y and linux-4.19.y. -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog
diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index 28bef94cf792..5962badb3346 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -611,7 +611,6 @@ asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr) handler[reason], smp_processor_id(), esr, esr_get_class_string(esr)); - die("Oops - bad mode", regs, 0); local_irq_disable(); panic("bad mode"); }