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#openstack-nova - 2021-11-12
11:27:28 opendevreview Stephen Finucane proposed openstack/nova master: db: Don't use legacy 'Row()' methods https://review.opendev.org/c/openstack/nova/+/817746
11:27:29 opendevreview Stephen Finucane proposed openstack/nova master: db: Remove unnecessary warning filters https://review.opendev.org/c/openstack/nova/+/817748
11:27:29 opendevreview Stephen Finucane proposed openstack/nova master: db: Remove use of 'bind' arguments https://review.opendev.org/c/openstack/nova/+/817747
13:17:46 giblet lyarwood, sean-k-mooney: so the patch with the sleep before detach now reproduced the kernel panic https://review.opendev.org/c/openstack/nova/+/817564/3#message-8ef45ae21f54b427ae2c88bbc19a4c926ce00883
13:18:15 giblet from the consol log it is clear that the kernel panic happened _before_ we trigger detach
13:18:28 sean-k-mooney is it possible the panic was tirggered by the attach
13:18:35 giblet or by the live migration
13:18:45 giblet or by the initial boot
13:18:50 giblet all possible
13:19:02 giblet so I will add more console printing step to the test case
13:19:10 giblet to see when the panic happens
13:20:19 sean-k-mooney looks liek it happend 19 seocnd after boot
13:20:53 giblet true, we can try to correlate that to the action in the test
13:21:22 sean-k-mooney the vm went active ~ 12:04:29
13:21:59 sean-k-mooney we did the attach at 12:04:40
13:22:34 sean-k-mooney actully no maybe i misread that
13:23:07 giblet 2021-11-12 12:04:30,036 99321 INFO [tempest.common.waiters] State transition "BUILD/spawning" ==> "ACTIVE/None" after 7 second wait
13:23:59 giblet 2021-11-12 12:04:38,573 99321 INFO [tempest.common.waiters] volume 0f307fda-dbef-408c-a029-97401db15945 reached in-use after waiting for 0.573394 seconds
13:24:16 sean-k-mooney looks liek we were just finsihing the mightation when the panic happend
13:24:47 sean-k-mooney it went active at 2021 12:04:52
13:25:36 giblet 2021-11-12 12:04:40,615 <- trigger the live migration
13:25:48 giblet 2021-11-12 12:04:52,693 99321 INFO [tempest.common.waiters] State transition "MIGRATING/migrating" ==> "ACTIVE/None" after 12 second wait
13:26:04 giblet yeah so the panic is somehow related to the live migration
13:26:06 sean-k-mooney yep
13:26:23 sean-k-mooney it woudl have been i gues at :49 ish
13:27:54 sean-k-mooney giblet: just looking at the panic
13:28:07 sean-k-mooney its realted to ipv6 adress configuraiton
13:28:36 giblet I saw at least 3 different kernel panic
13:28:43 giblet that test can produce
13:28:47 giblet this is the 4th one :)
13:29:21 sean-k-mooney well its specifclay failing in _raw_spin_lock_bh
13:30:26 lyarwood sorry have various trades people in my house today trying to sort something out
13:30:34 lyarwood really hard to focus on anything
13:31:45 sean-k-mooney lyarwood: tl;dr the panic happen during the migration in an interupt handel form _raw_spin_lock_bh at least in this insntace
13:32:25 sean-k-mooney so its before the detach in the cleanup phase if the time stames are correct
13:32:25 lyarwood giblet: remind me again, when did thi start failing?
13:32:28 lyarwood this*
13:32:32 giblet tehre is lot of different RIP codes in the reproductions https://paste.ubuntu.com/p/QGrtv2nZWz/
13:32:45 giblet lyarwood: on it ...
13:33:49 giblet lyarwood: the first panic was 2021-11-08T12:59:16
13:33:52 sean-k-mooney giblet: yes altoh galoto of them look like they are related to lcoking/interupt handeling in general
13:34:15 giblet this one https://zuul.opendev.org/t/openstack/build/c445dc25cb2c4567b223f05d95134c47
13:34:17 lyarwood giblet: kk it's not related to https://review.opendev.org/c/openstack/devstack/+/812928 then
13:36:41 giblet lyarwood: there is big gaps between nova-live-migration job run before 11.08.
13:36:44 giblet https://zuul.opendev.org/t/openstack/builds?job_name=nova-live-migration&project=openstack%2Fnova&branch=stable%2Fvictoria
13:36:58 giblet only 2 runs in october
13:38:14 giblet the newer october run still has the logs the older is already lost
13:39:26 sean-k-mooney looking at https://zuul.opendev.org/t/openstack/build/c445dc25cb2c4567b223f05d95134c47 that panic happend even eairlier in the test after 15 seconds
13:39:45 sean-k-mooney i have not check if that is during th migration or not but i suspect its also before the detach
13:40:54 sean-k-mooney 2021-11-08 12:41:10,502 99684 INFO [tempest.common.waiters] State transition "BUILD/spawning" ==> "ACTIVE/None" after 6 second wait
13:41:46 sean-k-mooney volume was attached at
13:41:48 sean-k-mooney 2021-11-08 12:41:18,780 99684 INFO [tempest.common.waiters] volume fb8d4e1c-5dae-41b4-a1d9-6ef20937997b reached in-use after waiting for 0.780033 seconds
13:42:09 sean-k-mooney and the migration finished at 2021-11-08 12:41:32,756 99684 INFO [tempest.common.waiters] State transition "MIGRATING/migrating" ==> "ACTIVE/None" after 12 second wait
13:42:31 sean-k-mooney so the panic was also during the live migration
13:43:05 sean-k-mooney so the detach is failing because the vm was dead after the migration
13:43:08 giblet I checked the oct 29 green run has the same qemu / libvirt version as the later failed runs
13:43:32 giblet qemu-system-x86 amd64 1:4.2-3ubuntu6.18 and libvirt0 amd64 6.0.0-0ubuntu8.14
13:47:17 sean-k-mooney im just checking dowstram if we have an closed bugs with live migration or painc in ther enames
13:47:33 sean-k-mooney 11
13:52:17 sean-k-mooney there are 3 nested virt issue that lok somewhat related but thos where this is happenign are not using that correct
13:55:04 giblet we have virt_type=qemu in the config
13:55:24 giblet so they are not nested guests
13:59:22 sean-k-mooney yes but im wonderign if nested virt is avaiabel and if the host are intel do they have kvm_intel.pml=1
13:59:56 sean-k-mooney its not nested kvm but its still a nested qemu instnace
14:00:34 sean-k-mooney actully the pml issue seams to be more related to live migrating the l1 vm not the l2 vm
14:09:05 sean-k-mooney so ya i dont see anything downstram that imidiatly screams this is a fixed qemu/kernel bug
14:13:46 giblet I did a summary in the bug and linket do this chat
14:44:47 belmoreira hi, I remember that in the past there were some discussions to have live migrations between cells.
14:45:03 belmoreira is there any progress on this?
14:45:55 giblet belmoreira: I think the cross cell migration work was stopped when mriedem left
14:45:57 sean-k-mooney we have not implemeted it
14:46:06 sean-k-mooney we have cross cell cold migratiohn/resize
14:46:23 sean-k-mooney belmoreira: there is no assumtion that hyperviors can talk to each other directly between cells
14:46:38 belmoreira yeah... is what I recall. And I think he was only working in cold migration as a starting point
14:46:38 sean-k-mooney belmoreira: they might be abel too but we decied we could not assuem that
14:47:06 sean-k-mooney giblet: the cross cell migration work is completed
14:47:14 sean-k-mooney giblet: that works but only cold migration
14:47:22 sean-k-mooney via effectivly a shelve
14:47:29 giblet yepp
14:47:30 sean-k-mooney and then unshelve to the new cell
14:48:35 belmoreira humm... I missed that in the release notes.
14:48:52 dansmith belmoreira: it's been like a couple years at this point.. :P
14:49:16 dansmith I dunno how reliable it is because I think it's very infrequently used, if that :/
14:49:55 sean-k-mooney i think its in train
14:50:11 sean-k-mooney but ya i don tknow if any of our downstream custoemr use it
14:50:24 sean-k-mooney most of them are not multi cell
14:50:26 belmoreira honestly, I was searching for it just few minutes ago... in all releases after Rocky because I recall that mriedem was working on it
14:51:08 belmoreira but anyway... what I'm looking at is a way to live migrate not cold migrate
14:51:11 sean-k-mooney oh its ussuri https://specs.openstack.org/openstack/nova-specs/specs/ussuri/implemented/cross-cell-resize.html
14:51:27 sean-k-mooney belmoreira: right we basically agree to not implemnte live migration
14:51:34 sean-k-mooney effectivly ever
14:51:40 dansmith sean-k-mooney: did we?
14:51:44 belmoreira :)
14:51:59 sean-k-mooney we could but it would reuiqre assumeing conenctivty betwenn the hyperviors in diffenet cells
14:52:01 dansmith IIRC it was going to be more complicated, very little audience, and so had no plans
14:52:19 sean-k-mooney dansmith: well i thinke the connectivty was the main blocker
14:52:21 dansmith sure, but live migration already assumes connectivity between hosts that not everyone allows, even in one cel
14:52:36 sean-k-mooney i gues that is true
14:52:52 belmoreira my use case is a one off... I'm trying to get rid of nova-network
14:53:06 dansmith my recollection was "if there's large uptake of cells and this becomes a thing lots of people want, we can consider, but no plans until then"

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