linux-kernel - Re: [patch] drivers/iommu: Fix iova DEBUG

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Date:	Wed, 15 Jun 2016 15:59:50 +0200
From:	"Cc: Joerg Roedel" <joro@...tes.org>
To:	Mike Galbraith <umgwanakikbuti@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Sagar Arun Kamble <sagar.a.kamble@...el.com>
Subject: Re: [patch] drivers/iommu: Fix iova DEBUG_PREEMPT splat

On Mon, Jun 13, 2016 at 02:56:36PM +0200, Mike Galbraith wrote:
> 
> Signed-off-by: Mike Galbraith <umgwanakikbuti@...il.com>
> Cc: Joerg Roedel <joro@...tes.org>
> ---
>  drivers/iommu/iova.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> --- a/drivers/iommu/iova.c
> +++ b/drivers/iommu/iova.c
> @@ -749,8 +749,9 @@ static bool __iova_rcache_insert(struct
>  	bool can_insert = false;
>  	unsigned long flags;
>  
> +	local_irq_save(flags);
>  	cpu_rcache = this_cpu_ptr(rcache->cpu_rcaches);
> -	spin_lock_irqsave(&cpu_rcache->lock, flags);
> +	spin_lock(&cpu_rcache->lock);
>  
>  	if (!iova_magazine_full(cpu_rcache->loaded)) {
>  		can_insert = true;
> @@ -812,8 +813,9 @@ static unsigned long __iova_rcache_get(s
>  	bool has_pfn = false;
>  	unsigned long flags;
>  
> +	local_irq_save(flags);
>  	cpu_rcache = this_cpu_ptr(rcache->cpu_rcaches);
> -	spin_lock_irqsave(&cpu_rcache->lock, flags);
> +	spin_lock(&cpu_rcache->lock);
>  
>  	if (!iova_magazine_empty(cpu_rcache->loaded)) {
>  		has_pfn = true;

>From an earlier patch submitted by Sagar (Cc'ed) I think the right fix
is to just make the code use get_cpu_ptr/put_cpu_ptr instead of
this_cpu_ptr.


	Joerg