On 03/27/2018 08:56 PM, Peter Krempa wrote: > On Mon, Mar 26, 2018 at 17:22:01 +0200, Michal Privoznik wrote: >> On 03/26/2018 05:17 PM, Peter Krempa wrote: >>> On Mon, Mar 26, 2018 at 16:43:02 +0200, Michal Privoznik wrote: >>>> https://bugzilla.redhat.com/show_bug.cgi?id=1557769 >>>> >>>> Problem with device mapper targets is that there can be several >>>> other devices 'hidden' behind them. For instance, /dev/dm-1 can >>>> consist of /dev/sda, /dev/sdb and /dev/sdc. Therefore, when >>>> setting up devices CGroup and namespaces we have to take this >>>> into account. >>>> >>>> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> >>>> --- > > [...] > >>>> + for (i = 0; i < nmaj; i++) { >>>> + if (virAsprintf(&devPath, "/dev/block/%u:%u", maj[i], min[i]) < 0) >>>> + goto cleanup; >>>> + >>>> + if (qemuDomainCreateDevice(devPath, data, false) < 0) >>>> + goto cleanup; >>> >>> So now that I see this new version, this part starts looking suspicious >>> to me. Since this did not care much that the path changed, is it really >>> necessary to create the /dev/ entries in the container? >>> >>> Looks like even device mapper is returning them as the node >>> specificator, so I'd presume it really does not matter if they are >>> present. >>> >>> More specifically we can't really reverse engineer from the major:minor >>> numbers which actual path the user used so it should not really be >>> necessary for it to be present in the container. >> >> Yes, looks like I was too eager trying to fix this bug. I've rebuilt >> libvirt without qemu_domain.c change (so only CGroup code was modified) >> and the bug still did not reproduce. So I guess namespace changes are >> not necessary after all. I'll drop them. > > Okay. Apart from that I thought about this for a while and also tested > various configurations. Unfortunately I was not able to reproduce the > issue. Looks like this is a kernel bug after all. I've also done some testing myself and fount that: a) on upstream kernel I'm unable to reproduce (4.15.11-gentoo), b) also 7.4 kenel works, c) it's only 7.5 where this bug presents itself. https://bugzilla.redhat.com/show_bug.cgi?id=1557769#c32 So I think we should ignore these patches for now until we have some input from kernel team. Michal -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list
