Date: Sun, 08 Jul 2012 12:39:14 -0500 From: Alan Cox <alc@rice.edu> To: Konstantin Belousov <kostikbel@gmail.com> Cc: alc@freebsd.org, Michael Butler <imb@protected-networks.net>, current@freebsd.org Subject: Re: sleeping thread panic? Message-ID: <4FF9C5C2.80509@rice.edu> In-Reply-To: <20120708165922.GE2338@deviant.kiev.zoral.com.ua> References: <4FF98128.6050607@protected-networks.net> <20120708133455.GX2338@deviant.kiev.zoral.com.ua> <4FF98F21.9060003@protected-networks.net> <20120708143113.GZ2338@deviant.kiev.zoral.com.ua> <4FF9A4A8.5050903@protected-networks.net> <4FF9BC03.1040008@protected-networks.net> <20120708165922.GE2338@deviant.kiev.zoral.com.ua>
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On 07/08/2012 11:59, Konstantin Belousov wrote:
> On Sun, Jul 08, 2012 at 12:57:39PM -0400, Michael Butler wrote:
>> -----BEGIN PGP SIGNED MESSAGE-----
>> Hash: SHA1
>>
>> On 07/08/12 11:18, Michael Butler wrote:
>>> On 07/08/12 10:31, Konstantin Belousov wrote:
>>>> Catch it next time ? This should be quite reproducable, if real.
>>>> Actually, try this.
>>>> diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
>>>> index 9485fdd..de33afc 100644
>>>> --- a/sys/vm/vm_pageout.c
>>>> +++ b/sys/vm/vm_pageout.c
>>>> @@ -1030,7 +1030,6 @@ rescan0:
>>>> ++pageout_lock_miss;
>>>> if (object->flags& OBJ_MIGHTBEDIRTY)
>>>> vnodes_skipped++;
>>>> - vm_page_lock_queues();
>>>> goto unlock_and_continue;
>> [ .. snip .. ]
>>
>>> Just waiting for the second of two attached RAID arrays to finish
>>> rebuilding and I'll give this a shot - thanks!
>> I repeated the dumps from last night over NFS with this patch installed
>> and no more panics :-)
> But, are panics reproducable without the patch ?
The patch looks correct. I'm sorry that I didn't catch this problem
when I reviewed the original patch yesterday. :-(
I don't think that you really need these assertions:
+ KASSERT(queues_locked, ("unlocked queues
2"));
+ mtx_assert(&vm_page_queue_mtx, MA_OWNED);
The control flow from the preceding acquire is straightforward and
vm_page_requeue() itself asserts that the page queues lock is held.
Alan
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