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I could also reproduce this bug on qemu-kvm-7.0.0-11.el9.x86_64.
After recovery the migration, migration will switch from postcopy-active to postcopy-paused by automatically in about 30 seconds, and can't be recovered：
1) src hmp log:
(qemu) 2022-08-29T06:42:09.462011Z qemu-kvm: failed to save SaveStateEntry with id(name): 1(ram): -5
2022-08-29T06:42:09.462082Z qemu-kvm: Detected IO failure for postcopy. Migration paused.
2) dst hmp log:
(qemu) 2022-08-29T06:42:09.461417Z qemu-kvm: postcopy_place_page: File exists copy host: 0x7f8277e00000 from: 0x7f827000cc18 (size: 4096)
2022-08-29T06:42:09.462035Z qemu-kvm: error while loading state section id 1(ram)
2022-08-29T06:42:09.462585Z qemu-kvm: Detected IO failure for postcopy. Migration paused.
I also reported one postcopy + multifd bug, I don't know whether they're releated:
Bug 2106726 - Qemu on destination host crashed if migrate with postcopy and multifd enabled
No immediate thing found from the logs.
Hopefully let's mark this as low priority. Since I have some other things to look at for today (and tomorrow public holiday here..) I may need to do that next week, sorry. But I'll update when I found something.
I didn't verify, but quickly checking the code, it seems we'll try to rebuild multifd channels too for postcopy recovery on dest qemu (migration_ioc_process_incoming()), however that won't work because src doesn't do that (migrate_fd_connect()).
Instead of fixing it, I'm thinking whether we should just disable postcopy with multifd completely because I can't think of anything that it could be useful, especially before a full support of them. We seem to be tackling with more than one issues for this but probably no one is using it.
Xiaohui/Fangge, do you have use case that enabling these two features can help in any form?
Hi Peter,
I didn't add postcopy + multifd test cases in migration test plan. I realized we should have supported postcopy + multifd from RHEL 9.1.0 which Juan told me.
So I tested the basic postcopy + multifd migration, and reported the following bug:
Bug 2106726 - Qemu on destination host crashed if migrate with postcopy and multifd enabled
Comment 10RHEL Program Management
2023-09-22 17:31:30 UTC
Issue migration from Bugzilla to Jira is in process at this time. This will be the last message in Jira copied from the Bugzilla bug.
Comment 11RHEL Program Management
2023-09-22 17:32:21 UTC
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Created attachment 1897633 [details] libvirt log Description of problem: Do postcopy migration with multifd enabled -> abort migration -> try to recover migration. Recover failed. Version-Release number of selected component (if applicable): libvirt-8.5.0-1.el9.x86_64 qemu-kvm-7.0.0-8.el9.x86_64 How reproducible: 100% Steps to Reproduce: 1. Start a vm 2. Do migration with multifd enabled [T1]# virsh migrate vm1 qemu+tcp://dell-per750-04******/system --live --postcopy --bandwidth 10 --auto-converge --p2p --parallel 3. Switch to postcopy before migration completes: [T2] # virsh migrate-postcopy vm1 4. Abort migration before it completes: [T2] # virsh domjobabort vm1 --postcopy [T1] error: operation failed: job 'migration in' failed in post-copy phase 5. Try to recover migration: [T1]# virsh migrate vm1 qemu+tcp://dell-per750-04******/system --live --postcopy --bandwidth 10 --auto-converge --p2p --parallel --postcopy-resume error: operation failed: job 'migration in' failed in post-copy phase [T1]# virsh migrate vm1 qemu+tcp://dell-per750-04******/system --live --postcopy --bandwidth 10 --auto-converge --p2p --parallel --postcopy-resume error: operation failed: job 'migration in' failed in post-copy phase Actual results: As step5, postcopy recover failed Expected results: postcopy recover succeeds. Additional info: 1. Src qemu log: 2022-07-16 10:00:43.147+0000: initiating migration 2022-07-16T10:00:47.810822Z qemu-kvm: Unable to write to socket: Broken pipe 2022-07-16T10:00:47.810955Z qemu-kvm: failed to save SaveStateEntry with id(name): 2(ram): -5 2022-07-16T10:00:47.810995Z qemu-kvm: Detected IO failure for postcopy. Migration paused. 2022-07-16 10:01:02.331+0000: resuming migration 2022-07-16T10:01:02.335987Z qemu-kvm: failed to save SaveStateEntry with id(name): 2(ram): -5 2022-07-16T10:01:02.336050Z qemu-kvm: Detected IO failure for postcopy. Migration paused. 2022-07-16 10:01:04.629+0000: resuming migration 2022-07-16T10:01:04.633004Z qemu-kvm: failed to save SaveStateEntry with id(name): 2(ram): -5 2022-07-16T10:01:04.633047Z qemu-kvm: Detected IO failure for postcopy. Migration paused. 2. Dest qemu log: 2022-07-16T10:00:47.827701Z qemu-kvm: error while loading state section id 2(ram) 2022-07-16T10:00:47.827770Z qemu-kvm: Detected IO failure for postcopy. Migration paused. 2022-07-16T10:01:02.345350Z qemu-kvm: postcopy_place_page: File exists copy host: 0x7f8fa7e00000 from: 0x5569d747c1ec (size: 4096) 2022-07-16T10:01:02.345363Z qemu-kvm: error while loading state section id 2(ram) 2022-07-16T10:01:02.345400Z qemu-kvm: Detected IO failure for postcopy. Migration paused. 2022-07-16T10:01:04.642370Z qemu-kvm: postcopy_place_page: File exists copy host: 0x7f8fa7e00000 from: 0x5569d747c1ec (size: 4096) 2022-07-16T10:01:04.642377Z qemu-kvm: error while loading state section id 2(ram) 2022-07-16T10:01:04.642406Z qemu-kvm: Detected IO failure for postcopy. Migration paused. 3. Src qemu monitor command: - {"execute":"migrate-set-capabilities","arguments":{"capabilities":[{"capability":"xbzrle","state":false},{"capability":"auto-converge","state":true},{"capability":"rdma-pin-all","state":false},{"capability":"postcopy-ram","state":true},{"capability":"compress","state":false},{"capability":"pause-before-switchover","state":true},{"capability":"late-block-activate","state":false},{"capability":"multifd","state":true},{"capability":"dirty-bitmaps","state":false},{"capability":"return-path","state":true},{"capability":"zero-copy-send","state":false}]},"id":"libvirt-408"} - {"execute":"migrate-set-parameters","arguments":{"tls-creds":"","tls-hostname":"","max-bandwidth":10485760},"id":"libvirt-409"} - {"execute":"migrate","arguments":{"detach":true,"blk":false,"inc":false,"resume":false,"uri":"tcp:dell-per750-04.******:49152"},"id":"libvirt-410"} - {"execute":"migrate-start-postcopy","id":"libvirt-411"} - {"execute":"migrate-continue","arguments":{"state":"pre-switchover"},"id":"libvirt-413"} - {"execute":"migrate-pause","id":"libvirt-415"} - {"execute":"migrate","arguments":{"detach":true,"blk":false,"inc":false,"resume":true,"uri":"tcp:dell-per750-04.******:49153"},"id":"libvirt-417"}