* [PATCH] x86/xen: Warn when there's no mfn for pfn
@ 2015-04-02 7:28 Ross Lagerwall
2015-04-02 9:00 ` David Vrabel
0 siblings, 1 reply; 3+ messages in thread
From: Ross Lagerwall @ 2015-04-02 7:28 UTC (permalink / raw)
To: xen-devel; +Cc: Ross Lagerwall, Boris Ostrovsky, David Vrabel
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.
Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
---
arch/x86/xen/mmu.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index adca9e2..4cacc11 100644
--- 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
--
2.1.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/xen: Warn when there's no mfn for pfn
2015-04-02 7:28 [PATCH] x86/xen: Warn when there's no mfn for pfn Ross Lagerwall
@ 2015-04-02 9:00 ` David Vrabel
2015-04-02 9:10 ` Ross Lagerwall
0 siblings, 1 reply; 3+ messages in thread
From: David Vrabel @ 2015-04-02 9:00 UTC (permalink / raw)
To: Ross Lagerwall, xen-devel; +Cc: Boris Ostrovsky, David Vrabel
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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] x86/xen: Warn when there's no mfn for pfn
2015-04-02 9:00 ` David Vrabel
@ 2015-04-02 9:10 ` Ross Lagerwall
0 siblings, 0 replies; 3+ messages in thread
From: Ross Lagerwall @ 2015-04-02 9:10 UTC (permalink / raw)
To: David Vrabel, xen-devel; +Cc: Boris Ostrovsky
On 04/02/2015 10:00 AM, David Vrabel wrote:
> 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.
>
That's unfortunate, I thought there may be some issue where it would be
triggered spuriously.
--
Ross Lagerwall
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2015-04-02 9:10 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
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2015-04-02 7:28 [PATCH] x86/xen: Warn when there's no mfn for pfn Ross Lagerwall
2015-04-02 9:00 ` David Vrabel
2015-04-02 9:10 ` Ross Lagerwall
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