From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: vhost changes (batched) in linux-next after 12/13 trigger random crashes in KVM guests after reboot Date: Fri, 7 Feb 2020 05:07:50 -0500 Message-ID: <20200207050731-mutt-send-email-mst@kernel.org> References: <20200120012724-mutt-send-email-mst@kernel.org> <2a63b15f-8cf5-5868-550c-42e2cfd92c60@de.ibm.com> <1ade56b5-083f-bb6f-d3e0-3ddcf78f4d26@de.ibm.com> <20200206171349-mutt-send-email-mst@kernel.org> <5c860fa1-cef5-b389-4ebf-99a62afa0fe8@de.ibm.com> <20200207025806-mutt-send-email-mst@kernel.org> <97c93d38-ef07-e321-d133-18483d54c0c0@de.ibm.com> <20200207095353.08bc91e4.cohuck@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20200207095353.08bc91e4.cohuck@redhat.com> Sender: kvm-owner@vger.kernel.org To: Cornelia Huck Cc: Christian Borntraeger , eperezma@redhat.com, "virtualization@lists.linux-foundation.org" , Stephen Rothwell , Linux Next Mailing List , "linux-kernel@vger.kernel.org" , kvm list , Halil Pasic List-Id: virtualization@lists.linuxfoundation.org On Fri, Feb 07, 2020 at 09:53:53AM +0100, Cornelia Huck wrote: > On Fri, 7 Feb 2020 09:13:14 +0100 > Christian Borntraeger wrote: > > > On 07.02.20 08:58, Michael S. Tsirkin wrote: > > > On Fri, Feb 07, 2020 at 08:47:14AM +0100, Christian Borntraeger wrote: > > >> Also adding Cornelia. > > >> > > >> > > >> On 06.02.20 23:17, Michael S. Tsirkin wrote: > > >>> On Thu, Feb 06, 2020 at 04:12:21PM +0100, Christian Borntraeger wrote: > > >>>> > > >>>> > > >>>> On 06.02.20 15:22, eperezma@redhat.com wrote: > > >>>>> Hi Christian. > > >>>>> > > >>>>> Could you try this patch on top of ("38ced0208491 vhost: use batched version by default")? > > >>>>> > > >>>>> It will not solve your first random crash but it should help with the lost of network connectivity. > > >>>>> > > >>>>> Please let me know how does it goes. > > >>>> > > >>>> > > >>>> 38ced0208491 + this seem to be ok. > > >>>> > > >>>> Not sure if you can make out anything of this (and the previous git bisect log) > > >>> > > >>> Yes it does - that this is just bad split-up of patches, and there's > > >>> still a real bug that caused worse crashes :) > > >>> > > >>> So I just pushed batch-v4. > > >>> I expect that will fail, and bisect to give us > > >>> vhost: batching fetches > > >>> Can you try that please? > > >>> > > >> > > >> yes. > > >> > > >> eccb852f1fe6bede630e2e4f1a121a81e34354ab is the first bad commit > > >> commit eccb852f1fe6bede630e2e4f1a121a81e34354ab > > >> Author: Michael S. Tsirkin > > >> Date: Mon Oct 7 06:11:18 2019 -0400 > > >> > > >> vhost: batching fetches > > >> > > >> With this patch applied, new and old code perform identically. > > >> > > >> Lots of extra optimizations are now possible, e.g. > > >> we can fetch multiple heads with copy_from/to_user now. > > >> We can get rid of maintaining the log array. Etc etc. > > >> > > >> Signed-off-by: Michael S. Tsirkin > > >> > > >> drivers/vhost/test.c | 2 +- > > >> drivers/vhost/vhost.c | 39 ++++++++++++++++++++++++++++++++++----- > > >> drivers/vhost/vhost.h | 4 +++- > > >> 3 files changed, 38 insertions(+), 7 deletions(-) > > >> > > > > > > > > > And the symptom is still the same - random crashes > > > after a bit of traffic, right? > > > > random guest crashes after a reboot of the guests. As if vhost would still > > write into now stale buffers. > > > > I'm late to the party; but where is that commit located? Or has it been > dropped again already? my vhost tree. Tag batch-v4.