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[68.160.176.52]) by smtp.gmail.com with ESMTPSA id n15sm5030276qti.51.2021.05.07.08.20.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 07 May 2021 08:20:25 -0700 (PDT) Date: Fri, 7 May 2021 11:20:25 -0400 From: Mike Snitzer To: Michael Tokarev Message-ID: References: <7104c94c-7408-0d58-ddd9-384102e820bc@msgid.tls.msk.ru> <6a71df25-d1fb-db02-ff55-384ba0828647@redhat.com> <84eaa68f-3ea3-8313-2953-46375dce9f86@msgid.tls.msk.ru> MIME-Version: 1.0 In-Reply-To: <84eaa68f-3ea3-8313-2953-46375dce9f86@msgid.tls.msk.ru> X-Mimecast-Impersonation-Protect: Policy=CLT - Impersonation Protection Definition; Similar Internal Domain=false; Similar Monitored External Domain=false; Custom External Domain=false; Mimecast External Domain=false; Newly Observed Domain=false; Internal User Name=false; Custom Display Name List=false; Reply-to Address Mismatch=false; Targeted Threat Dictionary=false; Mimecast Threat Dictionary=false; Custom Threat Dictionary=false X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-loop: dm-devel@redhat.com Cc: dm-devel@redhat.com, Zdenek Kabelac Subject: Re: [dm-devel] can we fix some dm snapshot crashes please? :) X-BeenThere: dm-devel@redhat.com X-Mailman-Version: 2.1.12 Precedence: junk List-Id: device-mapper development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dm-devel-bounces@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable On Fri, May 07 2021 at 10:10P -0400, Michael Tokarev wrote: > 07.05.2021 15:31, Zdenek Kabelac wrote: > > Dne 07. 05. 21 v 12:31 Michael Tokarev napsal(a): > ... > > > =A0=A0sz=3D$(blockdev --getsize /dev/loop0) > > > =A0=A0dmsetup create base --table "0 $sz snapshot-origin /dev/loop0" > > > =A0=A0# and now the crash > > > =A0=A0mkfs.ext4 /dev/mapper/base >=20 > > Yes reproducible - can you please open BZ report here: > >=20 > > https://bugzilla.redhat.com/enter_bug.cgi?product=3DLVM%20and%20device-= mapper >=20 > 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. >=20 > Actually I'm not aware about the wrong way. The documentation is a bit la= cking > 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-f= ly with > snapshot-origin table, but nowhere it is told that I can't create snapsho= t-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 variation= s. >=20 > I just tried to create a snapshot to be able to revert changes if somethi= ng 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 thin= g to use.. :) Yes, it is dangerous to stab in the dark like you clearly are doing. -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel