From: Keir Fraser <keir.fraser@eu.citrix.com>
To: MaoXiaoyun <tinnycloud@hotmail.com>
Cc: xen devel <xen-devel@lists.xensource.com>
Subject: Re: VM hung after running sometime
Date: Mon, 20 Sep 2010 08:45:21 +0100 [thread overview]
Message-ID: <C8BCCFA1.23804%keir.fraser@eu.citrix.com> (raw)
In-Reply-To: <BAY121-W11372E508EEF87C536CD8EDA7E0@phx.gbl>
On 20/09/2010 07:00, "MaoXiaoyun" <tinnycloud@hotmail.com> wrote:
> When IO is not ready, domain U in VMEXIT->hvm_do_resume might invoke
> wait_on_xen_event_channel
> (where it is blocked in _VPF_blocked_in_xen).
>
> Here is my assumption of event missed.
>
> step 1: hvm_do_resume execute 260, and suppose p->state is STATE_IOREQ_READY
> or STATE_IOREQ_INPROCESS
> step 2: then in cpu_handle_ioreq is in line 547, it execute line 548 so
> quickly before hvm_do_resume execute line 270.
> Well, the event is missed.
> In other words, the _VPF_blocked_in_xen is cleared before it is actually
> setted, and Domian U who is blocked
> might never get unblocked, it this possible?
Firstly, that code is very paranoid and it should never actually be the case
that we see STATE_IOREQ_READY or STATE_IOREQ_INPROCESS in hvm_do_resume().
Secondly, even if you do, take a look at the implementation of
wait_on_xen_event_channel() -- it is smart enough to avoid the race you
mention.
-- Keir
next prev parent reply other threads:[~2010-09-20 7:45 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <BAY121-W45A47AC73BDA1A9E7474A2DA720@phx.gbl>
[not found] ` <C8ACD97B.1256D%keir.fraser@eu.citrix.com>
2010-09-10 11:01 ` VM hung after running sometime MaoXiaoyun
2010-09-19 10:37 ` MaoXiaoyun
2010-09-19 11:49 ` Keir Fraser
2010-09-19 12:21 ` Zhang, Yang Z
2010-09-20 6:00 ` MaoXiaoyun
2010-09-20 7:45 ` Keir Fraser [this message]
2010-09-20 8:23 ` MaoXiaoyun
2010-09-20 9:15 ` MaoXiaoyun
2010-09-20 9:35 ` Keir Fraser
2010-09-21 5:02 ` MaoXiaoyun
2010-09-21 7:53 ` Keir Fraser
2010-09-21 9:24 ` wei song
2010-09-21 9:49 ` wei song
2010-09-21 17:28 ` Jeremy Fitzhardinge
2010-09-22 0:02 ` MaoXiaoyun
2010-09-22 0:17 ` Jeremy Fitzhardinge
2010-09-22 1:19 ` MaoXiaoyun
2010-09-22 18:31 ` Jeremy Fitzhardinge
2010-09-23 0:55 ` MaoXiaoyun
2010-09-23 23:20 ` Jeremy Fitzhardinge
2010-09-24 4:29 ` MaoXiaoyun
2010-09-25 9:33 ` MaoXiaoyun
2010-09-25 10:40 ` wei song
2010-09-27 18:02 ` Jeremy Fitzhardinge
2010-09-27 11:56 ` MaoXiaoyun
2010-09-28 5:43 ` MaoXiaoyun
2010-09-28 11:23 ` MaoXiaoyun
2010-09-28 17:07 ` Jeremy Fitzhardinge
2010-09-29 6:01 ` MaoXiaoyun
2010-09-29 16:12 ` Jeremy Fitzhardinge
2010-10-15 12:43 ` Domain 0 stop response on frequently reboot VMS MaoXiaoyun
2010-10-15 12:57 ` Keir Fraser
2010-10-16 5:39 ` MaoXiaoyun
2010-10-16 7:16 ` Keir Fraser
2010-10-18 21:17 ` Daniel Stodden
2010-10-24 5:48 ` MaoXiaoyun
2010-10-24 5:56 ` Daniel Stodden
2010-10-26 8:16 ` MaoXiaoyun
2010-10-26 9:09 ` Daniel Stodden
2010-10-26 10:54 ` MaoXiaoyun
2010-10-26 9:20 ` Ian Campbell
2010-10-26 10:59 ` MaoXiaoyun
2010-10-26 11:54 ` Domain 0 stop response on frequently reboot VMS, fix xen/master link? Pasi Kärkkäinen
2010-10-26 17:08 ` Jeremy Fitzhardinge
2010-11-04 3:09 ` A Patch for modify DomU network transmit rate dynamically MaoXiaoyun
2010-11-04 3:43 ` MaoXiaoyun
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