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Re: [Xen-devel] blktap2 bug:Assertion 'list_empty(&vreq->next)' failed

To: Daniel Stodden <daniel.stodden@xxxxxxxxxx>
Subject: Re: [Xen-devel] blktap2 bug:Assertion 'list_empty(&vreq->next)' failed
From: tsk <aixt2006@xxxxxxxxx>
Date: Mon, 28 Jun 2010 12:58:59 +0800
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, xen-users <xen-users@xxxxxxxxxxxxxxxxxxx>
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It is found that some assertion was in the tapdisk2 source, if anyone failed, the tapdisk2 process will exit, 
They are very dangerous...
How can the kernel handle this if the tapdisk2 process exit?

2010/6/28 Daniel Stodden <daniel.stodden@xxxxxxxxxx>
On Mon, 2010-06-28 at 00:41 -0400, tsk wrote:
> Hi folks,
> Yestoday, I run a testcase, 6 VMs restart every 10 minitues from 11:00
> am to 16:30 pm until Dom0 crashed.
> Assertion 'list_empty(&vreq->next)' failed will lead to tapdisk2
> process segfault, then Dom0 crashed!
> Jun 27 16:31:05 r02k05014 kernel: device tap775.0 entered promiscuous
> mode
> Jun 27 16:31:05 r02k05014 kernel: eth0: port 13(tap775.0) entering
> forwarding state
> Jun 27 16:31:15 r02k05014 tapdisk2[4341]: Assertion
> 'list_empty(&vreq->next)' failed, line 1822, file tapdisk-vbd.c
> Jun 27 16:31:15 r02k05014 kernel: tapdisk2[4341]: segfault at 0 ip
> 000000000040a24f sp 00007fff0d8acb70 error 6 in tapdisk2[400000+39000]
> Jun 28 18:58:09 r02k05014 syslogd 1.4.1: restart.
> Any one who can give me some tips?

Semi-yes. Not entirely sure about the list_empty userland crasher, but
the kernel stuff was upstreamed with some minor exposed while unmapping
pending I/O.

Which I didn't care yet to send patches for...

... Soon, real soon now...


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