The d_automount is the callback into the filesystem to mount a sub- filesystem upon access to a directory. autofs does use it, but nfs uses it too for subshares even without autofs.
So far I'm not seeing any connection between my patch and the crash, I'm wondering if you've encountered another bug just by coincidence. I don't know the code in question well though so there may be something I'm missing. The "fix" isn't really a final fix though, just testing an idea I had about what might be causing it. 4.4.0-38 contains a patch (backported from 4.8) which changes the current credentials to those of root before trying to automount a submount, so that a recently added capability check will pass. I guessed that the id changes might be causing kerberos authentication to fail, so the patch makes a copy of the user's credentials but with the required capability instead of using root's creds. The root of the kernel crash messages looks to be a GPF when reading from an rpc pipe, which has nothing to do with the credentials that I can see. So I'm not sure how the two would be connected. The fact that it does help tells me that I'm on the right track though. -- 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/1649292 Title: NFS client : permission denied when trying to access subshare, since kernel 4.4.0-31 Status in linux package in Ubuntu: In Progress Status in linux source package in Xenial: Triaged Bug description: Similar like Bug #1603719 or Bug #1604396 i got a "Permission denied" when trying to access a NFS subshare from our NFSv4 Server. I tried this under (K)ubuntu Trusty and Xenial and also with the ubuntu based Mint Versions 17.3 Rosa an 18 Sarah. Kernel Versions higher than 4.4.0-31 from offical Ubuntu Repository has the problem. Before 4.4.0-31 not. For safety reasons i used the linux-generic-lts-wily meta package The 4.4 mainline kernel also works without problem currently (4.4.37-040437-generic) Our NFS server runs under FreeBSD 11, but same problems to the clients with FreeBSD 10.3 and OmniOS r151018. All NFS servers use ZFS as the filesystem and NFSv4 with kerberos for sharing. For the basic structure we use also ZFS filesystems. So my homefolder is located on the server under /apool/AIS/share/home/staff/fili/linux ... each level is a ZFS filesystem. On the client nfs share /apool/AIS/share/home is mounted under /home/VI My posix homedirectory path is /home/VI/staff/fili/linux When i try to login i got access to /home/VI/staff/fili ... but when i try to access the linux directory / zfs filesystem i got the permission denied. The fstab options for /home/VI are _netdev,rw,sync,sec=krb5,nfsvers=4,clientaddr=w.x.y.z I tried also autofs but with the same result. --- ApportVersion: 2.20.1-0ubuntu2.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: system 1812 F.... pulseaudio /dev/snd/controlC0: system 1812 F.... pulseaudio DistroRelease: Ubuntu 16.04 HibernationDevice: RESUME=UUID=85a1880e-b78e-49d6-888c-342e47405712 InstallationDate: Installed on 2016-10-17 (56 days ago) InstallationMedia: Kubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719) IwConfig: enp7s0 no wireless extensions. lo no wireless extensions. MachineType: System manufacturer System Product Name NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia Package: linux (not installed) ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-57-generic root=UUID=db11df78-a07d-44b5-8fe3-0f67e7a5ff51 ro ProcVersionSignature: Ubuntu 4.4.0-57.78-generic 4.4.35 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-4.4.0-57-generic N/A linux-backports-modules-4.4.0-57-generic N/A linux-firmware 1.157.5 RfKill: Tags: xenial Uname: Linux 4.4.0-57-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: _MarkForUpload: True dmi.bios.date: 09/24/2010 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 1205 dmi.board.asset.tag: To Be Filled By O.E.M. dmi.board.name: P6T WS PRO dmi.board.vendor: ASUSTeK Computer INC. dmi.board.version: Rev 1.xx dmi.chassis.asset.tag: Asset-1234567890 dmi.chassis.type: 3 dmi.chassis.vendor: Chassis Manufacture dmi.chassis.version: Chassis Version dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1205:bd09/24/2010:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP6TWSPRO:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion: dmi.product.name: System Product Name dmi.product.version: System Version dmi.sys.vendor: System manufacturer --- ApportVersion: 2.20.1-0ubuntu2.2 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: system 1876 F.... pulseaudio /dev/snd/controlC0: system 1876 F.... pulseaudio DistroRelease: Ubuntu 16.04 HibernationDevice: RESUME=UUID=85a1880e-b78e-49d6-888c-342e47405712 InstallationDate: Installed on 2016-10-17 (56 days ago) InstallationMedia: Kubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719) IwConfig: enp7s0 no wireless extensions. lo no wireless extensions. MachineType: System manufacturer System Product Name NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia Package: linux (not installed) ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.4.0-57-generic root=UUID=db11df78-a07d-44b5-8fe3-0f67e7a5ff51 ro ProcVersionSignature: Ubuntu 4.4.0-57.78-generic 4.4.35 PulseList: Error: command ['pacmd', 'list'] failed with exit code 1: No PulseAudio daemon running, or not running as session daemon. RelatedPackageVersions: linux-restricted-modules-4.4.0-57-generic N/A linux-backports-modules-4.4.0-57-generic N/A linux-firmware 1.157.5 RfKill: Tags: xenial xenial Uname: Linux 4.4.0-57-generic x86_64 UpgradeStatus: No upgrade log present (probably fresh install) UserGroups: _MarkForUpload: True dmi.bios.date: 09/24/2010 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 1205 dmi.board.asset.tag: To Be Filled By O.E.M. dmi.board.name: P6T WS PRO dmi.board.vendor: ASUSTeK Computer INC. dmi.board.version: Rev 1.xx dmi.chassis.asset.tag: Asset-1234567890 dmi.chassis.type: 3 dmi.chassis.vendor: Chassis Manufacture dmi.chassis.version: Chassis Version dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1205:bd09/24/2010:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP6TWSPRO:rvrRev1.xx:cvnChassisManufacture:ct3:cvrChassisVersion: dmi.product.name: System Product Name dmi.product.version: System Version dmi.sys.vendor: System manufacturer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1649292/+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
