From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from meiko.romanrm.net ([195.154.92.155]:55434 "EHLO meiko.romanrm.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933132AbcATPIF (ORCPT ); Wed, 20 Jan 2016 10:08:05 -0500 Date: Wed, 20 Jan 2016 20:08:00 +0500 From: Roman Mamedov To: Paolo Bonzini Cc: bo.li.liu@oracle.com, linux-btrfs@vger.kernel.org, kvm@vger.kernel.org Subject: Re: Kernel 4.4.0 KVM guest on Btrfs locks up on snapshotting Message-ID: <20160120200800.6858d6ee@natsu> In-Reply-To: <569F70AA.2030006@redhat.com> References: <20160120030223.22cc3ae0@natsu> <20160120001944.GA9884@localhost.localdomain> <20160120100852.470479a6@natsu> <569F70AA.2030006@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/tFCtLXIvuwn4vCAcQb+ocZ="; protocol="application/pgp-signature" Sender: linux-btrfs-owner@vger.kernel.org List-ID: --Sig_/tFCtLXIvuwn4vCAcQb+ocZ= Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 20 Jan 2016 12:34:02 +0100 Paolo Bonzini wrote: > On 20/01/2016 06:08, Roman Mamedov wrote: > > I don't get any ENOSPC errors on the host, also it doesn't seem to > > be a slowdown caused by disk I/O searching for free space, just a > > complete lock-up: I monitor the guest with 'ping', and when it > > happens, the ping responses stop immediately and do not return, > > also there is no reaction to any keypress in the KVM VNC window. >=20 > Can you go to the QEMU monitor (Ctrl-Alt-F2 typically, or just add > "-monitor stdio" to the QEMU command line) and type "info status"? Aha, now this is getting somewhere. ------------------ (qemu) info status VM status: paused (io-error) (qemu) info block hd: vm.img (raw) I/O status: nospace Detect zeroes: unmap ide1-cd0: [not inserted] Removable device: not locked, tray closed floppy0: [not inserted] Removable device: not locked, tray closed sd0: [not inserted] Removable device: not locked, tray closed (qemu) info block-jobs No active jobs ------------------ So this seems to be an transient ENOSPC error returned to the data writing process by the FS during snapshotting. I can now reproduce this without KVM, just with dd. Seems not much to do with KVM then, I will post more details = to the btrfs list. Thanks! --=20 With respect, Roman --Sig_/tFCtLXIvuwn4vCAcQb+ocZ= Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlafotAACgkQTLKSvz+PZwjasACfWcsxV6stukHnqSjaXlbw76hx y1wAn0Ewyg5XIvR5xmX+3tRKcPCAPB4+ =5aMo -----END PGP SIGNATURE----- --Sig_/tFCtLXIvuwn4vCAcQb+ocZ=--