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 02:58:32 -0500 Message-ID: <20200207025806-mutt-send-email-mst@kernel.org> References: <20200107042401-mutt-send-email-mst@kernel.org> <20200107065434-mutt-send-email-mst@kernel.org> <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <5c860fa1-cef5-b389-4ebf-99a62afa0fe8@de.ibm.com> Sender: kvm-owner@vger.kernel.org To: Christian Borntraeger Cc: eperezma@redhat.com, "virtualization@lists.linux-foundation.org" , Stephen Rothwell , Linux Next Mailing List , "linux-kernel@vger.kernel.org" , kvm list , Halil Pasic , Cornelia Huck List-Id: virtualization@lists.linuxfoundation.org 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? > > >