Public bug reported: == Comment: #0 - Cyril Bur <[email protected]> - 2015-02-23 18:03:41 == +++ This bug was initially created as a clone of Bug #108455 +++
I was investigating the cause of some ppc64le KVM guest softlockup warnings. On a single CPU KVM guest, I ran something to keep the guest busy: yes > /dev/null & Followed by (qemu) stop Wait a while, then: (qemu) cont We get a softlockup error: BUG: soft lockup - CPU#0 stuck for 9220s! [yes:2389] .__getnstimeofday .getnstimeofday .ktime_get_real .netif_receive_skb .ibmveth_poll .net_rx_action .__do_softirq .irq_exit .__do_irq .call_do_irq .do_IRQ I was going to file it away in the "don't do that" bin, but I notice x86 have something to detect a paused VM and avoid spewing the soft lockup error. Do we need something like this on ppc64? commit 5d1c0f4a80a6df73395fb3fc2c302510f8f09d36 Author: Eric B Munson <[email protected]> Date: Sat Mar 10 14:37:28 2012 -0500 watchdog: add check for suspended vm in softlockup detector A suspended VM can cause spurious soft lockup warnings. To avoid these, the watchdog now checks if the kernel knows it was stopped by the host and skips the warning if so. When the watchdog is reset successfully, clear the guest paused flag. == Comment: #1 - Cyril Bur <[email protected]> - 2015-02-23 18:03:55 == Hi, I have been working on a fix for guest kernels. This requires two patches: 1/2 commit 545a2bf742fb41f17d03486dd8a8c74ad511dec2 Author: Cyril Bur <[email protected]> Date: Thu Feb 12 15:01:24 2015 -0800 kernel/sched/clock.c: add another clock for use with the soft lockup watchdog and 2/2 commit 4be1b29795d692d512bb67b770665d6f8ea5cb0b Author: Cyril Bur <[email protected]> Date: Thu Feb 12 15:01:28 2015 -0800 powerpc: add running_clock for powerpc to prevent spurious softlockup warnings Both are in upstream. ** Affects: ubuntu Importance: Undecided Status: New ** Tags: architecture-ppc64le bugnameltc-122013 severity-medium targetmilestone-inin1504 ** Tags added: architecture-ppc64le bugnameltc-122013 severity-medium targetmilestone-inin1504 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1427075 Title: Stopping and starting KVM partitions results in guest kernel softlockup To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1427075/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
