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

[Colin Ian King]

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?


> ---
>  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);
>