apport information ** Attachment added: "CurrentDmesg.txt" https://bugs.launchpad.net/bugs/1834693/+attachment/5274472/+files/CurrentDmesg.txt
-- 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/1834693 Title: Simultaneous creation and teardown of separate loops causes udev softlock Status in linux package in Ubuntu: Confirmed Bug description: 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. --- 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. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1834693/+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
