From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH] x86/xen: Warn when there's no mfn for pfn
Date: Thu, 2 Apr 2015 10:00:54 +0100
Message-ID: <551D0546.8040702@citrix.com>
References: <1427959690-4682-1-git-send-email-ross.lagerwall@citrix.com>
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To: Ross Lagerwall <ross.lagerwall@citrix.com>, xen-devel@lists.xenproject.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>, David Vrabel <david.vrabel@citrix.com>
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On 02/04/15 08:28, Ross Lagerwall wrote:
> I recently had to debug dom0 taking a fatal page fault and it would have
> been useful if it warned when creating a non-present pte if there's no
> mfn for a pfn.

This will trigger for ever PTE covering memory hotplugged by the balloon
driver, so I don't think we can take this.

David

> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -397,6 +397,7 @@ static pteval_t pte_pfn_to_mfn(pteval_t val)
>  		 * pte_mfn_to_pfn is asymmetric.
>  		 */
>  		if (unlikely(mfn == INVALID_P2M_ENTRY)) {
> +			printk(KERN_WARNING "No mfn for pfn %lx, creating non-present pte\n", pfn);
>  			mfn = 0;
>  			flags = 0;
>  		} else
>