On Fri, May 07 2021 at 10:10P -0400, Michael Tokarev <mjt@xxxxxxxxxx> wrote: > 07.05.2021 15:31, Zdenek Kabelac wrote: > > Dne 07. 05. 21 v 12:31 Michael Tokarev napsal(a): > ... > > > sz=$(blockdev --getsize /dev/loop0) > > > dmsetup create base --table "0 $sz snapshot-origin /dev/loop0" > > > # and now the crash > > > mkfs.ext4 /dev/mapper/base > > > Yes reproducible - can you please open BZ report here: > > > > https://bugzilla.redhat.com/enter_bug.cgi?product=LVM%20and%20device-mapper > > Ok, will do, thanks! Thanks. But when you do, please tone down the lamenting of how slow snapshot crashes have been fixed -- or don't. But that line of rhetoric shows you're full of it. > > I assume you are aware you are trying to using snapshot target in wrong way, > > but it should not be crashing kernel. > > Actually I'm not aware about the wrong way. The documentation is a bit lacking > in this area. There are a few (maybe 2 or 3) guides describing the steps to do, > most involves first using an 1:1 linear table, next replacing it on-the-fly with > snapshot-origin table, but nowhere it is told that I can't create snapshot-origin > directly, or that I need at least one snapshot device, or that the origin of the > snapshot-origin table should be a dm device, or many many other variations. > > I just tried to create a snapshot to be able to revert changes if something goes > wrong, and since I don't use lvm I thought that plain dmsetup should do, but > discovered that it doesn't quite work and it actually is a dangerous thing to use.. :) Yes, it is dangerous to stab in the dark like you clearly are doing. -- dm-devel mailing list dm-devel@xxxxxxxxxx https://listman.redhat.com/mailman/listinfo/dm-devel
