apport information ** Tags added: apport-collected xenial
** Description changed: What I expected to happen: Loops can be successfully created and removed from multiple different threads without any adverse effects What happened instead: Udev processes ended up in D state, which soft locked the system (unable to reboot without resorting to "echo b > /proc/sysrq-trigger", various other commands [losetup -a, mount -l] would hang) The use case that this was originally reproduced on required frequent setup and teardown of loops in order to persist and access various snapshots of backup files. Through various methods of analysis, we were able to create a script that recreates the bad behavior relatively quickly (see attachment testudevLoopOnly.php). - We captured some stack traces from a locked up system, and found that - many of the calls were originating from loop.c. Investigating that file - (specifically lo_setup and lo_release functions) showed that the 4.4 - usage of mutexes is different from earlier versions of the kernel - package (4.4.0.142.148), which doesn't exhibit this same behavior. It's - also different from the 4.15 version of the kernel package, which also - does not exhibit the same (incorrect) behavior. + We captured some stack traces from a locked up system, and found that many of the calls were originating from loop.c. Investigating that file (specifically lo_setup and lo_release functions) showed that the 4.4 usage of mutexes is different from earlier versions of the kernel package (4.4.0.142.148), which doesn't exhibit this same behavior. It's also different from the 4.15 version of the kernel package, which also does not exhibit the same (incorrect) behavior. + --- + AlsaVersion: Advanced Linux Sound Architecture Driver Version k4.4.0-148-generic. + AplayDevices: Error: [Errno 2] No such file or directory + ApportVersion: 2.20.1-0ubuntu2.18 + Architecture: amd64 + ArecordDevices: Error: [Errno 2] No such file or directory + AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/hwC0D0', '/dev/snd/pcmC0D8p', '/dev/snd/pcmC0D7p', '/dev/snd/pcmC0D3p', '/dev/snd/controlC0', '/dev/snd/hwC1D2', '/dev/snd/pcmC1D2c', '/dev/snd/pcmC1D1p', '/dev/snd/pcmC1D0c', '/dev/snd/pcmC1D0p', '/dev/snd/controlC1', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1: + Card0.Amixer.info: Error: [Errno 2] No such file or directory + Card0.Amixer.values: Error: [Errno 2] No such file or directory + Card1.Amixer.info: Error: [Errno 2] No such file or directory + Card1.Amixer.values: Error: [Errno 2] No such file or directory + DistroRelease: Ubuntu 16.04 + IwConfig: Error: [Errno 2] No such file or directory + MachineType: Gigabyte Technology Co., Ltd. H97N + NonfreeKernelModules: zfs zunicode icp zcommon znvpair zavl + Package: linux (not installed) + ProcEnviron: + TERM=xterm-256color + PATH=(custom, no user) + XDG_RUNTIME_DIR=<set> + LANG=en_US.UTF-8 + SHELL=/bin/bash + ProcFB: 0 inteldrmfb + ProcKernelCmdLine: BOOT_IMAGE=(loop)/vmlinuz root=UUID=02d26ec8-92ae-414a-9332-4e57f62f9bd3 rootdelay=120 rw quiet panic=5 vga=791 consoleblank=0 max_loop=256 splash loop=/images/704.0.img net.ifnames=0 nomdmonisw nomdmonddf bootdegraded=true audit=1 + ProcVersionSignature: Ubuntu 4.4.0-148.174-generic 4.4.177 + RelatedPackageVersions: + linux-restricted-modules-4.4.0-148-generic N/A + linux-backports-modules-4.4.0-148-generic N/A + linux-firmware 1.157.21 + RfKill: Error: [Errno 2] No such file or directory + Tags: xenial + Uname: Linux 4.4.0-148-generic x86_64 + UpgradeStatus: No upgrade log present (probably fresh install) + UserGroups: + + _MarkForUpload: True + dmi.bios.date: 06/10/2014 + dmi.bios.vendor: American Megatrends Inc. + dmi.bios.version: F1 + dmi.board.asset.tag: To be filled by O.E.M. + dmi.board.name: H97N + dmi.board.vendor: Gigabyte Technology Co., Ltd. + dmi.board.version: x.x + dmi.chassis.asset.tag: To Be Filled By O.E.M. + dmi.chassis.type: 3 + dmi.chassis.vendor: Gigabyte Technology Co., Ltd. + dmi.chassis.version: To Be Filled By O.E.M. + dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrF1:bd06/10/2014:svnGigabyteTechnologyCo.,Ltd.:pnH97N:pvrTobefilledbyO.E.M.:rvnGigabyteTechnologyCo.,Ltd.:rnH97N:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvrToBeFilledByO.E.M.: + dmi.product.name: H97N + dmi.product.version: To be filled by O.E.M. + dmi.sys.vendor: Gigabyte Technology Co., Ltd. ** Attachment added: "AlsaDevices.txt" https://bugs.launchpad.net/bugs/1834693/+attachment/5274468/+files/AlsaDevices.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1834693 Title: Simultaneous creation and teardown of separate loops causes udev softlock To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1834693/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
