loadvm fails twice in sequence

Bug #1712564 reported by Dr. David Alan Gilbert
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
QEMU
Fix Released
Undecided
Unassigned

Bug Description

13:38:23) shorne_: Hello, I was doing some testing with migrations for my OpenRISC SMP patch set, I noticed something that looks like a bug, wondering if someone else wants to confirm
(13:38:47) shorne_: Basically, calling loadvm 2 times causes crash
(13:38:54) shorne_: migration/savevm.c: qemu_event_set(&mis->main_thread_load_event)
(13:38:54) stefanha: fam: Here is my take at this change: https://paste.debian.net/982690/
(13:38:56) shorne_: assert(ev->initialized) - fails inside
(13:39:32) stefanha: quintela davidgiluk: ^
(13:41:23) ***davidgiluk looks
(13:41:40) shorne_: c096358e747 util/qemu-thread-posix.c (Fam Zheng 2017-07-04 20:23:25 +0800 397) assert(ev->initialized);
(13:41:51) davidgiluk: shorne_: So you're doing a loadvm to load a snapshot and then again?
(13:42:02) shorne_: Looks like adding that assert() was done really recently
(13:42:41) shorne_: yes, just loadvm 'a' ... then wait a bit longer, loadvm 'a' again (confirm clocks go back etc)
(13:42:50) stefanha: fam: While you're having dinner I'll work on turning my script into a qemu-iotests test case that we can merge.
(13:44:03) gpiccoli [~gpiccoli@0002093a.user.oftc.net] entered the room.
(13:44:21) davidgiluk: shorne_: Well, it looks like the c09635 assert is a sanity check to make sure we didn't do anything stupid, and well.....
(13:44:57) pm215: migration_incoming_get_current() and migration_incoming_state_destroy() seem a bit mismatched
(13:45:13) davidgiluk: pm215: Yep
(13:45:46) davidgiluk: pm215: Generally we've thought that an incoming migration normally only happens once - shorne_'s case is the exception
(13:46:03) shorne_: pm215: yeah, it looked something like that I just had a few seconds to look at today
(13:46:03) HariharanTS left the room (quit: Ping timeout: 480 seconds).
(13:46:03) shorne_ is now known as shorne
(13:48:05) shorne: davidgiluk: pm215: thanks for having a look. Unfortunately I need to head off to bed and put kids to sleep
(13:49:11) davidgiluk: shorne: Sleep well, no nightmares about event destroyers....
(13:49:30) davidgiluk: pm215: Yeh this is fall out from b4b076daf32

Revision history for this message
Dr. David Alan Gilbert (dgilbert-h) wrote :

Posted:
migration: Reset rather than destroy main_thread_load_event
snapshot/tests: Try loadvm twice

Changed in qemu:
status: New → In Progress
Revision history for this message
Dr. David Alan Gilbert (dgilbert-h) wrote :

Commit 5089e1862fe80b6f23ba4c494e2902cbe3d9d48e

Changed in qemu:
status: In Progress → Fix Committed
Thomas Huth (th-huth)
Changed in qemu:
status: Fix Committed → Fix Released
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