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[209.132.183.28]) by mx.google.com with ESMTPS id iu8si5724038pbc.94.2015.09.08.07.14.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 08 Sep 2015 07:14:05 -0700 (PDT) Date: Tue, 8 Sep 2015 15:13:56 +0100 From: "Dr. David Alan Gilbert" Subject: Re: [Qemu-devel] [PATCH 19/23] userfaultfd: activate syscall Message-ID: <20150908141356.GM2246@work-vm> References: <1431624680-20153-20-git-send-email-aarcange@redhat.com> <20150811100728.GB4587@in.ibm.com> <20150811134826.GI4520@redhat.com> <20150812052346.GC4587@in.ibm.com> <1441692486.14597.17.camel@ellerman.id.au> <20150908063948.GB678@in.ibm.com> <20150908085946.GC2246@work-vm> <20150908095915.GC678@in.ibm.com> <20150908124652.GK2246@work-vm> <20150908133647.GA17433@in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150908133647.GA17433@in.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: Bharata B Rao Cc: Michael Ellerman , Andrea Arcangeli , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, qemu-devel@nongnu.org, kvm@vger.kernel.org, linux-api@vger.kernel.org, zhang.zhanghailiang@huawei.com, Pavel Emelyanov , Johannes Weiner , Hugh Dickins , Sanidhya Kashyap , Dave Hansen , Andres Lagar-Cavilla , Mel Gorman , Paolo Bonzini , "Kirill A. Shutemov" , "Huangpeng (Peter)" , Andy Lutomirski , Linus Torvalds , Peter Feiner , linuxppc-dev@lists.ozlabs.org * Bharata B Rao (bharata@linux.vnet.ibm.com) wrote: > On Tue, Sep 08, 2015 at 01:46:52PM +0100, Dr. David Alan Gilbert wrote: > > * Bharata B Rao (bharata@linux.vnet.ibm.com) wrote: > > > On Tue, Sep 08, 2015 at 09:59:47AM +0100, Dr. David Alan Gilbert wrote: > > > > * Bharata B Rao (bharata@linux.vnet.ibm.com) wrote: > > > > > In fact I had successfully done postcopy migration of sPAPR guest with > > > > > this setup. > > > > > > > > Interesting - I'd not got that far myself on power; I was hitting a problem > > > > loading htab ( htab_load() bad index 2113929216 (14848+0 entries) in htab stream (htab_shift=25) ) > > > > > > > > Did you have to make any changes to the qemu code to get that happy? > > > > > > I should have mentioned that I tried only QEMU driven migration within > > > the same host using wp3-postcopy branch of your tree. I don't see the > > > above issue. > > > > > > (qemu) info migrate > > > capabilities: xbzrle: off rdma-pin-all: off auto-converge: off zero-blocks: off compress: off x-postcopy-ram: on > > > Migration status: completed > > > total time: 39432 milliseconds > > > downtime: 162 milliseconds > > > setup: 14 milliseconds > > > transferred ram: 1297209 kbytes > > > throughput: 270.72 mbps > > > remaining ram: 0 kbytes > > > total ram: 4194560 kbytes > > > duplicate: 734015 pages > > > skipped: 0 pages > > > normal: 318469 pages > > > normal bytes: 1273876 kbytes > > > dirty sync count: 4 > > > > > > I will try migration between different hosts soon and check. > > > > I hit that on the same host; are you sure you've switched into postcopy mode; > > i.e. issued a migrate_start_postcopy before the end of migration? > > Sorry I was following your discussion with Li in this thread > > https://www.marc.info/?l=qemu-devel&m=143035620026744&w=4 > > and it wasn't obvious to me that anything apart from turning on the > x-postcopy-ram capability was required :( OK. > So I do see the problem now. > > At the source > ------------- > Error reading data from KVM HTAB fd: Bad file descriptor > Segmentation fault > > At the target > ------------- > htab_load() bad index 2113929216 (14336+0 entries) in htab stream (htab_shift=25) > qemu-system-ppc64: error while loading state section id 56(spapr/htab) > qemu-system-ppc64: postcopy_ram_listen_thread: loadvm failed: -22 > qemu-system-ppc64: VQ 0 size 0x100 Guest index 0x0 inconsistent with Host index 0x1f: delta 0xffe1 > qemu-system-ppc64: error while loading state for instance 0x0 of device 'pci@800000020000000:00.0/virtio-net' > *** Error in `./ppc64-softmmu/qemu-system-ppc64': corrupted double-linked list: 0x00000100241234a0 *** > ======= Backtrace: ========= > /lib64/power8/libc.so.6Segmentation fault Good - my current world has got rid of the segfaults/corruption in the cleanup on power - but those are only after it stumbled over the htab problem. I don't know the innards of power/htab, so if you've got any pointers on what upset it I'd be happy for some pointers. (We should probably trim the cc - since I don't think this is userfault related). Dave -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org