git: d1cbe7908986 - main - Allocating the LinuxKPI current structure from an interrupt thread must be done using the M_NOWAIT flag after 1ae20f7c70ea .

[Konstantin Belousov]

On Wed, Mar 10, 2021 at 09:52:27AM +0000, Hans Petter Selasky wrote:
> The branch main has been updated by hselasky:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=d1cbe79089868226625c12ef49f51214d79aa427
> 
> commit d1cbe79089868226625c12ef49f51214d79aa427
> Author:     Hans Petter Selasky <hselasky at FreeBSD.org>
> AuthorDate: 2021-03-10 09:50:01 +0000
> Commit:     Hans Petter Selasky <hselasky at FreeBSD.org>
> CommitDate: 2021-03-10 09:51:04 +0000
> 
>     Allocating the LinuxKPI current structure from an interrupt thread must be
>     done using the M_NOWAIT flag after 1ae20f7c70ea .
>     
>     MFC after:      1 week
>     Sponsored by:   Mellanox Technologies // NVIDIA Networking
> ---
>  sys/compat/linuxkpi/common/src/linux_compat.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/sys/compat/linuxkpi/common/src/linux_compat.c b/sys/compat/linuxkpi/common/src/linux_compat.c
> index 2ad936311204..707c5e47512e 100644
> --- a/sys/compat/linuxkpi/common/src/linux_compat.c
> +++ b/sys/compat/linuxkpi/common/src/linux_compat.c
> @@ -2384,7 +2384,8 @@ linux_irq_handler(void *ent)
>  {
>  	struct irq_ent *irqe;
>  
> -	linux_set_current(curthread);
> +	if (linux_set_current_flags(curthread, M_NOWAIT))
> +		return;
>  
>  	irqe = ent;
>  	irqe->handler(irqe->irq, irqe->arg);
This probably hangs machine instead of panicing.  In low memory condition,
you do not handle interrupt, which probably mean that the source is not
silenced, and after EOI the same interrupt will be generated again.