[SRU][bionic][PATCH 4/5] powerpc/powernv: Fix opal_event_shutdown() called with interrupts disabled

[Kamal Mostafa]

On Wed, Sep 5, 2018 at 9:00 AM Colin Ian King <colin.king at canonical.com>
wrote:

> On 05/09/18 16:48, Kamal Mostafa wrote:
> > From: Nicholas Piggin <npiggin at gmail.com>
> >
> > BugLink: http://bugs.launchpad.net/bugs/1790636
> >
> > A kernel crash in process context that calls emergency_restart from
> > panic will end up calling opal_event_shutdown with interrupts disabled
> > but not in interrupt. This causes a sleeping function to be called
> > which gives the following warning with sysrq+c:
> >
> >     Rebooting in 10 seconds..
> >     BUG: sleeping function called from invalid context at
> kernel/locking/mutex.c:238
> >     in_atomic(): 0, irqs_disabled(): 1, pid: 7669, name: bash
> >     CPU: 20 PID: 7669 Comm: bash Tainted: G      D W         4.17.0-rc5+
> #3
> >     Call Trace:
> >     dump_stack+0xb0/0xf4 (unreliable)
> >     ___might_sleep+0x174/0x1a0
> >     mutex_lock+0x38/0xb0
> >     __free_irq+0x68/0x460
> >     free_irq+0x70/0xc0
> >     opal_event_shutdown+0xb4/0xf0
> >     opal_shutdown+0x24/0xa0
> >     pnv_shutdown+0x28/0x40
> >     machine_shutdown+0x44/0x60
> >     machine_restart+0x28/0x80
> >     emergency_restart+0x30/0x50
> >     panic+0x2a0/0x328
> >     oops_end+0x1ec/0x1f0
> >     bad_page_fault+0xe8/0x154
> >     handle_page_fault+0x34/0x38
> >     --- interrupt: 300 at sysrq_handle_crash+0x44/0x60
> >     LR = __handle_sysrq+0xfc/0x260
> >     flag_spec.62335+0x12b844/0x1e8db4 (unreliable)
> >     __handle_sysrq+0xfc/0x260
> >     write_sysrq_trigger+0xa8/0xb0
> >     proc_reg_write+0xac/0x110
> >     __vfs_write+0x6c/0x240
> >     vfs_write+0xd0/0x240
> >     ksys_write+0x6c/0x110
> >
> > Fixes: 9f0fd0499d30 ("powerpc/powernv: Add a virtual irqchip for opal
> events")
> > Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> > Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
> > Signed-off-by: Kamal Mostafa <kamal at canonical.com>
> > (cherry picked from commit 8bf84f005346fd0ecfa595c2d497b19a6e291b4e)
> > Signed-off-by: Kamal Mostafa <kamal at canonical.com>
>
>
> I can't find 8bf84f005346fd0ecfa595c2d497b19a6e291b4e in linux or
> linux-next.  Where does it come from?
>
>
Ooops, that needs to be corrected, to:
(cherry picked from commit c0beffc4f4c658fde86d52c837e784326e9cc875)

 -Kamal


> > ---
> >  arch/powerpc/platforms/powernv/opal-irqchip.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/arch/powerpc/platforms/powernv/opal-irqchip.c
> b/arch/powerpc/platforms/powernv/opal-irqchip.c
> > index 9d1b8c0..05ffe05 100644
> > --- a/arch/powerpc/platforms/powernv/opal-irqchip.c
> > +++ b/arch/powerpc/platforms/powernv/opal-irqchip.c
> > @@ -177,7 +177,7 @@ void opal_event_shutdown(void)
> >               if (!opal_irqs[i])
> >                       continue;
> >
> > -             if (in_interrupt())
> > +             if (in_interrupt() || irqs_disabled())
> >                       disable_irq_nosync(opal_irqs[i]);
> >               else
> >                       free_irq(opal_irqs[i], NULL);
> >
>
>
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