I tested the patches earlier, so it should be good. But just for the record: I just pulled the trusty master-next branch, built and tested on the test vm. The crash doesn't occur for me anymore in the reported scenario.
Atm, it looks like the fix will be in 3.13.0-54 but afaik we have to wait for 53 to be cleared out of proposed first. The fix also seems to be in the upstream linux SRUs (or whatever it's called) so other distros will likely get it as well. Once -54 makes it to proposed I'll get some of our users to try it out, see if that was the only issue causing those crashes. But I'm optimistic. (Btw. on -53 it still crashes instantly, as expected) -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1450584 Title: mono occassionally crashes since kernel 3.13.0-48 on multi-cpu vm Status in linux package in Ubuntu: In Progress Status in linux source package in Trusty: Fix Committed Status in linux source package in Utopic: Fix Committed Status in linux source package in Vivid: Fix Committed Bug description: [Impact] The addition of the commit: http://kernel.ubuntu.com/git/ubuntu/ubuntu-trusty.git/commit/?id=11f4e0339c8dc8d760483258efd9f15b4c6dcda2 Causes SIGSEGVs when running certain workloads on multi-cpu VMs. [Test Case] Mono test case here that causes the SIGSEGV https://bugzilla.xamarin.com/show_bug.cgi?id=29212 [Fix] These two commits are required for fixing this issue: https://github.com/torvalds/linux/commit/80f7fdb1c7f0f9266421f823964fd1962681f6ce https://github.com/torvalds/linux/commit/0a4e6be9ca17c54817cf814b4b5aa60478c6df27 -- Gradually since late March more and more users started to complain about frequent SIGSEGV crashes in our .net/mono application. Early April I started to investigate it actively. After eliminating possible native libraries, and testing various mono versions I discovered the crashes would occur more frequently on a vbox vm with multiple cpus configured. And discovered that the mono bug-18026.cs testcase would fairly consistently crash. At that point it was reported to the mono bug tracker. I finally got a break when we found a correlation with the kernel version. 3.13.0-46 didn't crash while 3.13.0-48,49 did. More and more users upgrade to these newer kernel versions and start running into issues, which explains the gradual increase in reports. Early this week I performed a full git bisect on the kernel between 3.13.0-46 and -48 and isolated the commit that seems to trigger the crashes. Namely http://kernel.ubuntu.com/git/ubuntu/ubuntu-trusty.git/commit/?id=11f4e0339c8dc8d760483258efd9f15b4c6dcda2 At this point I don't know if the commit messed up something, or that mono simply handles it incorrectly. However, a few commits for linux 4.x seem to fix it: https://github.com/torvalds/linux/commit/80f7fdb1c7f0f9266421f823964fd1962681f6ce https://github.com/torvalds/linux/commit/0a4e6be9ca17c54817cf814b4b5aa60478c6df27 I applied these commits myself on top of commit 11f4e033, compiled and ran the testcase... didn't crash in the 200x test runs I did. Although I don't know if those two patches have unknown side-effects. I'm not an expert on the kernel, not even remotely. But I thought it would be nice to be able to point at a possible solution. My current test vm is a virtualbox vm 64bit installed using the 14.04.2 server iso running on an older i7 quad core Windows 7 64bit host. In the vm I've tested numerous mono and kernel combinations. Last test was with kernel 3.16.0-36 and 3.13.0-51 and mono 4.0.1, in which the problem still occurs. By now I've debugged the app using gdb several dozen times on various user setups, compiled mono half a dozen times, and then the 8x3h compile kernel bisect :) Speaking of down the rabbit-hole... So I'm pretty desperate for some expert to help me out here. :D Reference to mono bug report: https://bugzilla.xamarin.com/show_bug.cgi?id=29212 ProblemType: Bug DistroRelease: Ubuntu 14.04 Package: linux-image-3.13.0-51-generic 3.13.0-51.84 ProcVersionSignature: Ubuntu 3.13.0-51.84-generic 3.13.11-ckt18 Uname: Linux 3.13.0-51-generic x86_64 AlsaDevices: total 0 crw-rw---- 1 root audio 116, 1 Apr 30 18:53 seq crw-rw---- 1 root audio 116, 33 Apr 30 18:53 timer AplayDevices: Error: [Errno 2] No such file or directory: 'aplay' ApportVersion: 2.14.1-0ubuntu3.10 Architecture: amd64 ArecordDevices: Error: [Errno 2] No such file or directory: 'arecord' AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: CRDA: Error: [Errno 2] No such file or directory: 'iw' CurrentDmesg: [ 9.379188] init: plymouth-upstart-bridge main process ended, respawning Date: Thu Apr 30 19:45:43 2015 HibernationDevice: RESUME=UUID=b35ef328-166d-4476-a418-e7e80d22cb30 InstallationDate: Installed on 2015-04-22 (7 days ago) InstallationMedia: Ubuntu-Server 14.04.2 LTS "Trusty Tahr" - Release amd64 (20150218.1) IwConfig: eth0 no wireless extensions. lo no wireless extensions. Lsusb: Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub MachineType: innotek GmbH VirtualBox ProcEnviron: TERM=screen PATH=(custom, no user) XDG_RUNTIME_DIR=<set> LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: 0 VESA VGA ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-51-generic root=UUID=68da7e09-1a91-4107-859d-bf452f9ed992 ro RelatedPackageVersions: linux-restricted-modules-3.13.0-51-generic N/A linux-backports-modules-3.13.0-51-generic N/A linux-firmware 1.127.11 RfKill: Error: [Errno 2] No such file or directory: 'rfkill' SourcePackage: linux UpgradeStatus: No upgrade log present (probably fresh install) dmi.bios.date: 12/01/2006 dmi.bios.vendor: innotek GmbH dmi.bios.version: VirtualBox dmi.board.name: VirtualBox dmi.board.vendor: Oracle Corporation dmi.board.version: 1.2 dmi.chassis.type: 1 dmi.chassis.vendor: Oracle Corporation dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr: dmi.product.name: VirtualBox dmi.product.version: 1.2 dmi.sys.vendor: innotek GmbH To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1450584/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
