All of
 help / color / mirror / Atom feed
From: Lennert Buytenhek <>
Subject: fedora 10 x86_64 breakage under KVM, due to KVM_CLOCK
Date: Mon, 20 Apr 2009 13:26:13 +0200	[thread overview]
Message-ID: <> (raw)

(please CC, not on the list)

Hi all,

Fedora 10 randomly hangs for me when run under KVM, whereas (unpatched)
F9 works fine.  When this happens, kvm_stat shows that the VM is seeing
1000 IRQ exits per second, but nothing else seems to happen.  The latest
F9 update kernel seems to be bust as well.  (I noticed that the KVM guest
support status page says that "Alexey E." is seeing the same thing.)

I tried about two dozen different kernel packages from koji, and it turns
out that kernel-2.6.26-0.122.rc9.git4.fc10 is the last known good kernel,
and kernel-2.6.26-0.124.rc9.git5.fc10 is the first kernel that's broken.

The F10 instability appears since this commit (attached below as well):;a=commit;h=a5991f36968f44d4d3c64fc5aaa285a21de1ba54

I built three new kernels from the latest 2.6.27-170.2.56.fc10 update
in Fedora 10:
1. One with PARAVIRT and all associated options disabled entirely.
2. One with only KVM_GUEST disabled.
3. One with only KVM_CLOCK disabled (and paravirt and KVM_GUEST enabled).

Kernel (1) is stable.  Kernel (2) is unstable like the unpatched F10
kernels are, in that it randomly locks up.  Kernel (3) is stable as
well, which suggests that KVM_CLOCK is what's causing the lockups.

I tried booting the original F10 update kernel with no-kvmclock on
the command line as well, and that makes things stable as well.

I tried with the latest F10 updates-testing kernel (,
and that shows the same thing: with no-kvmclock it works fine, otherwise
it hangs randomly.

Running KVM 84 on x86_64 CentOS 5.3, with the kvm rpms from
The host CPU is a Q6600 Core 2 Quad.

Any ideas?


commit a5991f36968f44d4d3c64fc5aaa285a21de1ba54
Author: davej <davej>
Date:   Wed Jul 9 04:54:02 2008 +0000

    Reenable paravirt on x86-64.

diff --git a/config-x86_64-generic b/config-x86_64-generic
index e0c1e61..a2dd13c 100644
--- a/config-x86_64-generic
+++ b/config-x86_64-generic
@@ -254,7 +254,11 @@ CONFIG_INTEL_IOATDMA=m
 # CONFIG_COMPAT_VDSO is not set
diff --git a/kernel.spec b/kernel.spec
index cd4b749..ff4c12a 100644
--- a/kernel.spec
+++ b/kernel.spec
@@ -21,7 +21,7 @@ Summary: The Linux kernel
 # works out to the offset from the rebase, so it doesn't get too ginormous.
 %define fedora_cvs_origin 623
-%define fedora_build %(R="$Revision: 1.744 $"; R="${R%% \$}"; R="${R##: 1.}"; expr $R - %{fedora_cvs_origin})
+%define fedora_build %(R="$Revision: 1.745 $"; R="${R%% \$}"; R="${R##: 1.}"; expr $R - %{fedora_cvs_origin})
 # base_sublevel is the kernel version we're starting with and patching
 # on top of -- for example, 2.6.22-rc7-git1 starts with a 2.6.21 base,
@@ -1794,6 +1794,9 @@ fi
 %kernel_variant_files -a /%{image_install_path}/xen*-%{KVERREL}.xen -e /etc/{KVERREL}.xen.conf %{with_xen} xen
+* Wed Jul 09 2008 Dave Jones <>
+- Reenable paravirt on x86-64.
 * Tue Jul  8 2008 Roland McGrath <>
 - new bleeding-edge utrace code

             reply	other threads:[~2009-04-20 11:25 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-04-20 11:26 Lennert Buytenhek [this message]
2009-04-20 11:56 ` Avi Kivity
2009-04-25 21:30   ` Lennert Buytenhek

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \
    --subject='Re: fedora 10 x86_64 breakage under KVM, due to KVM_CLOCK' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.