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Message-ID: <4D777CDA.3050500@univ-nantes.fr>
Date:	Wed, 09 Mar 2011 14:12:58 +0100
From:	Jean-Philippe Menil <jean-philippe.menil@...v-nantes.fr>
To:	"Michael S. Tsirkin" <mst@...hat.com>
CC:	netdev@...r.kernel.org, kvm@...r.kernel.org,
	virtualization@...ts.linux-foundation.org
Subject: Re: Bug inkvm_set_irq

Le 09/03/2011 14:00, Michael S. Tsirkin a écrit :
> On Wed, Mar 09, 2011 at 01:28:43PM +0100, Jean-Philippe Menil wrote:
>> Le 08/03/2011 12:13, Michael S. Tsirkin a écrit :
>>> On Fri, Mar 04, 2011 at 10:39:05AM +0100, Jean-Philippe Menil wrote:
>>>> Yes, it's a 2.6.37.2 kernel.
>>> OK, here's a debugging patch.
>>> Please run with slab debugging as previously until you see
>>> 'eventfd bug detected!' in dmesg or until there is a crash.
>>> It might be also useful to enable timestampts on printk with
>>>   Symbol: PRINTK_TIME [=y]
>>>    │ Type  : boolean
>>>    │ Prompt: Show timing information on printks
>>>
>>> once you see the error, please upload the
>>> full dmesg output somewhere to we can track what
>>> goes on.
>>>
>>> Hopefully there won't be an oops this time which
>>> should make it easier for you to test (no need to
>>> reboot).
>>>
>>>
>>> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
>>> index c1f1e3c..3cb679b 100644
>>> --- a/virt/kvm/eventfd.c
>>> +++ b/virt/kvm/eventfd.c
>>> @@ -32,6 +32,7 @@
>>>   #include<linux/eventfd.h>
>>>   #include<linux/kernel.h>
>>>   #include<linux/slab.h>
>>> +#include<linux/nmi.h>
>>>
>>>   #include "iodev.h"
>>>
>>> @@ -43,6 +44,8 @@
>>>    * --------------------------------------------------------------------
>>>    */
>>>
>>> +#define KVM_BAD_PTR ((void*)(long)(0x6b6b6b6b6b6b6b6bull))
>>> +
>>>   struct _irqfd {
>>>   	struct kvm               *kvm;
>>>   	struct eventfd_ctx       *eventfd;
>>> @@ -61,6 +64,13 @@ irqfd_inject(struct work_struct *work)
>>>   {
>>>   	struct _irqfd *irqfd = container_of(work, struct _irqfd, inject);
>>>   	struct kvm *kvm = irqfd->kvm;
>>> +	if (kvm == KVM_BAD_PTR) {
>>> +		printk(KERN_ERR "Eventfd bug detected!\n");
>>> +		printk(KERN_ERR "%s(work=%p,irqfd=%p,kvm=%p,gsi=%d)\n", __func__,
>>> +			work, irqfd, kvm, irqfd->gsi);
>>> +		trigger_all_cpu_backtrace();
>>> +		return;
>>> +	}
>>>
>>>   	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
>>>   	kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
>>> @@ -75,6 +85,8 @@ irqfd_shutdown(struct work_struct *work)
>>>   	struct _irqfd *irqfd = container_of(work, struct _irqfd, shutdown);
>>>   	u64 cnt;
>>>
>>> +	printk(KERN_ERR "%s(work=%p,irqfd=%p,kvm=%p, gsi=%d)\n", __func__,
>>> +	       work, irqfd, irqfd->kvm, irqfd->gsi);
>>>   	/*
>>>   	 * Synchronize with the wait-queue and unhook ourselves to prevent
>>>   	 * further events.
>>> @@ -91,6 +103,8 @@ irqfd_shutdown(struct work_struct *work)
>>>   	 * It is now safe to release the object's resources
>>>   	 */
>>>   	eventfd_ctx_put(irqfd->eventfd);
>>> +	printk(KERN_ERR "kfree at %s(work=%p,irqfd=%p)\n", __func__,
>>> +	       work, irqfd);
>>>   	kfree(irqfd);
>>>   }
>>>
>>> @@ -111,6 +125,8 @@ static void
>>>   irqfd_deactivate(struct _irqfd *irqfd)
>>>   {
>>>   	BUG_ON(!irqfd_is_active(irqfd));
>>> +	printk(KERN_ERR "%s(irqfd=%p,kvm=%p, gsi=%d)\n", __func__,
>>> +	       irqfd, irqfd->kvm, irqfd->gsi);
>>>
>>>   	list_del_init(&irqfd->list);
>>>
>>> @@ -178,6 +194,8 @@ kvm_irqfd_assign(struct kvm *kvm, int fd, int gsi)
>>>
>>>   	irqfd->kvm = kvm;
>>>   	irqfd->gsi = gsi;
>>> +	printk(KERN_ERR "%s(irqfd=%p,kvm=%p, gsi=%d)\n", __func__,
>>> +	       irqfd, kvm, gsi);
>>>   	INIT_LIST_HEAD(&irqfd->list);
>>>   	INIT_WORK(&irqfd->inject, irqfd_inject);
>>>   	INIT_WORK(&irqfd->shutdown, irqfd_shutdown);
>>> @@ -264,6 +282,8 @@ kvm_irqfd_deassign(struct kvm *kvm, int fd, int gsi)
>>>   	struct _irqfd *irqfd, *tmp;
>>>   	struct eventfd_ctx *eventfd;
>>>
>>> +	printk(KERN_ERR "%s(kvm=%p, gsi=%d)\n", __func__,
>>> +	       kvm, gsi);
>>>   	eventfd = eventfd_ctx_fdget(fd);
>>>   	if (IS_ERR(eventfd))
>>>   		return PTR_ERR(eventfd);
>>> @@ -305,6 +325,7 @@ void
>>>   kvm_irqfd_release(struct kvm *kvm)
>>>   {
>>>   	struct _irqfd *irqfd, *tmp;
>>> +	printk(KERN_ERR "%s(kvm=%p)\n", __func__, kvm);
>>>
>>>   	spin_lock_irq(&kvm->irqfds.lock);
>>>
>>> --
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>> Hi,
>>
>> I boot the host with the patched kernel yesterday.
>> No crach until now, but two "Eventfd bug detected!" in the log at
>> "Mar  9 02:04:31" and "Mar  9 02:15:17"
>> You can find part of the log at the following adress:
>> http://filex.univ-nantes.fr/get?k=jL4Fe7yfSMN57toAH7V
>>
>> It a split file of the kern.log (1,4G), so if you need another part
>> of the log, let me know.
>>
>> Thanks for all.
>>
>> Regards.
> Downloading, it's big :)
> What about some 1000 lines before and after Eventfd bug detected! line?
> --
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Yes, sorry about that.
I could have split my log into a smaller file.

I was a little afraid of not transmit enough informations, and i was a 
bit wide.
I hope you can find usefull trace anyway.

Regards.

-- 
Jean-Philippe Menil - Pôle réseau Service IRTS
DSI Université de Nantes
jean-philippe.menil@...v-nantes.fr
Tel : 02.53.48.49.27 - Fax : 02.53.48.49.09

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