linux-kernel - Re: [PATCH] PCI, x86: clear initial value for root info resources

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Date:	Fri, 21 Sep 2012 12:50:26 -0400
From:	Konrad Rzeszutek Wilk <konrad@...nel.org>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH] PCI, x86: clear initial value for root info resources

On Wed, Sep 19, 2012 at 10:49:00AM -0700, Yinghai Lu wrote:
> Found one system one root bus hot remove get panic.

Boy, this is mangled.

Can you include the name of the system? Perhaps you can
rephrase this to say:

"On XYZ removing the root bus (through ACPI unplug) causes
a panic."

> Panic happens when try to release hostbridge resource.

Can you include the stack trace?
> 
> It turns out that resource get reject during put into resource tree
> because of conflicts.

Come again? Are you saying:

"The reason for this is that the resources was never initialized
properly because of .. (what type of conflict?)"?

> Also that resource parent pointer have random value.
> 
> That invalid value cause it pass through check __release_pci_root_info
> and panic in release_resource.
> 
> Try to use kzalloc instead.

It is not just try, it _is_ using that now.

> 
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
> Cc: x86@...nel.org
> 
> ---
>  arch/x86/pci/acpi.c |    3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> Index: linux-2.6/arch/x86/pci/acpi.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/pci/acpi.c
> +++ linux-2.6/arch/x86/pci/acpi.c
> @@ -305,7 +305,6 @@ setup_resource(struct acpi_resource *acp
>  	res->flags = flags;
>  	res->start = start;
>  	res->end = end;
> -	res->child = NULL;
>  
>  	if (!pci_use_crs) {
>  		dev_printk(KERN_DEBUG, &info->bridge->dev,
> @@ -434,7 +433,7 @@ probe_pci_root_info(struct pci_root_info
>  
>  	size = sizeof(*info->res) * info->res_num;
>  	info->res_num = 0;
> -	info->res = kmalloc(size, GFP_KERNEL);
> +	info->res = kzalloc(size, GFP_KERNEL);
>  	if (!info->res)
>  		return;
>  
> --
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