I am having the same problem on ubuntu 16.04.2, kernel 4.4.0-75-generic, and on a mint 18 system, kernel 4.4.0-21-generic. I have several cifs mounts, and if any one server becomes unresponsive, then any process attempting to access the mounts will hang indefinitely. If I unmount using -l and wait several minutes, eventually these hung processes will resume (with an error). I am mounting with the "soft" option.
The hung process stack looks like: $ sudo cat /proc/7771/stack [<ffffffffc030970d>] cifs_reconnect_tcon+0x9d/0x340 [cifs] [<ffffffffc0309a5a>] smb_init+0x2a/0x50 [cifs] [<ffffffffc0310c53>] CIFSSMBQPathInfo+0x63/0x2e0 [cifs] [<ffffffffc033c20f>] cifs_query_path_info+0x6f/0x1a0 [cifs] [<ffffffffc032ae80>] cifs_get_inode_info+0x390/0x8f0 [cifs] [<ffffffffc032d425>] cifs_revalidate_dentry_attr+0x1d5/0x250 [cifs] [<ffffffffc032d551>] cifs_getattr+0x51/0x110 [cifs] [<ffffffff81213a6c>] vfs_getattr_nosec+0x2c/0x40 [<ffffffff81213c86>] vfs_getattr+0x26/0x30 [<ffffffff81213d68>] vfs_fstatat+0x78/0xc0 [<ffffffff81214311>] SYSC_newlstat+0x31/0x60 [<ffffffff8121444e>] SyS_newlstat+0xe/0x10 [<ffffffff8183b972>] entry_SYSCALL_64_fastpath+0x16/0x71 [<ffffffffffffffff>] 0xffffffffffffffff ** Changed in: linux (Ubuntu) Status: Expired => New -- 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/1073648 Title: CIFS hangs if server goes down, even if 'soft' is enabled Status in linux package in Ubuntu: New Bug description: Hi, I have a NAS mounted as follows: //mybook/Public /mnt/mybook cifs nodev,soft,_netdev,noexec,nosuid,uid=1000 0 2 Unfortunately, the 'soft' option doesn't seem to be honored. When the server goes down, all programs lock up trying to access it and cannot be killed (kill -9 is ineffective). Umount yields and error unless -l is given, in which case it hangs. dmesg has the following messages: [ 2160.228973] INFO: task rsync:20808 blocked for more than 120 seconds. [ 2160.228975] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 2160.228978] rsync D 0000000000000002 0 20808 1 0x00000004 [ 2160.228982] ffff8801c1305878 0000000000000082 ffff8801c1305fd8 0000000000000286 [ 2160.228987] ffff8801c1305fd8 ffff8801c1305fd8 ffff8801c1305fd8 00000000000137c0 [ 2160.228992] ffff88010c5cc500 ffff88032b4edc00 ffff8801c1305868 ffff8802bb624220 [ 2160.228996] Call Trace: [ 2160.229001] [<ffffffff81658f2f>] schedule+0x3f/0x60 [ 2160.229004] [<ffffffff81659d37>] __mutex_lock_slowpath+0xd7/0x150 [ 2160.229008] [<ffffffff8165ae3e>] ? _raw_spin_lock+0xe/0x20 [ 2160.229012] [<ffffffff8165994a>] mutex_lock+0x2a/0x50 [ 2160.229018] [<ffffffffa0eb393c>] cifs_reconnect_tcon+0x18c/0x310 [cifs] [ 2160.229022] [<ffffffff8108ab80>] ? add_wait_queue+0x60/0x60 [ 2160.229029] [<ffffffffa0eb49e7>] small_smb_init+0x37/0x80 [cifs] [ 2160.229036] [<ffffffffa0eb6921>] cifs_async_readv+0x71/0x180 [cifs] [ 2160.229045] [<ffffffffa0ec9a28>] cifs_readpages+0x288/0x430 [cifs] [ 2160.229049] [<ffffffff81122a78>] read_pages+0x48/0x100 [ 2160.229053] [<ffffffff81122c93>] __do_page_cache_readahead+0x163/0x180 [ 2160.229057] [<ffffffff81123001>] ra_submit+0x21/0x30 [ 2160.229061] [<ffffffff81123125>] ondemand_readahead+0x115/0x230 [ 2160.229065] [<ffffffff811232c8>] page_cache_async_readahead+0x88/0xb0 [ 2160.229071] [<ffffffff813108fe>] ? radix_tree_lookup_slot+0xe/0x10 [ 2160.229076] [<ffffffff81117b6e>] ? find_get_page+0x1e/0x90 [ 2160.229081] [<ffffffff811184a9>] do_generic_file_read.constprop.33+0x269/0x440 [ 2160.229086] [<ffffffff8111941f>] generic_file_aio_read+0xef/0x280 [ 2160.229091] [<ffffffff8117792a>] do_sync_read+0xda/0x120 [ 2160.229096] [<ffffffff8129d5f3>] ? security_file_permission+0x93/0xb0 [ 2160.229100] [<ffffffff81177db1>] ? rw_verify_area+0x61/0xf0 [ 2160.229103] [<ffffffff81178290>] vfs_read+0xb0/0x180 [ 2160.229106] [<ffffffff811783aa>] sys_read+0x4a/0x90 [ 2160.229110] [<ffffffff81663442>] system_call_fastpath+0x16/0x1b So far, the only remedy to clear the programs (and bring the mount back online) is to reboot. Thanks! ProblemType: Bug DistroRelease: Ubuntu 12.04 Package: linux-image-3.2.0-32-generic 3.2.0-32.51 ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30 Uname: Linux 3.2.0-32-generic x86_64 NonfreeKernelModules: nvidia AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24. ApportVersion: 2.0.1-0ubuntu14 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: chicken 3776 F.... pulseaudio /dev/snd/controlC0: chicken 3776 F.... pulseaudio CRDA: Error: [Errno 2] No such file or directory Card0.Amixer.info: Card hw:0 'Intel'/'HDA Intel at 0xf7df8000 irq 79' Mixer name : 'Realtek ALC889' Components : 'HDA:10ec0889,104383c0,00100004' Controls : 47 Simple ctrls : 23 Card1.Amixer.info: Card hw:1 'NVidia'/'HDA NVidia at 0xfbcfc000 irq 34' Mixer name : 'Nvidia GPU 11 HDMI/DP' Components : 'HDA:10de0011,10de0101,00100100' Controls : 24 Simple ctrls : 4 Date: Wed Oct 31 10:03:45 2012 HibernationDevice: RESUME=UUID=34cbfc6f-a406-4efe-aacc-f563db40fa2f IwConfig: Error: [Errno 2] No such file or directory MachineType: System manufacturer System Product Name ProcEnviron: LANGUAGE=en_US:en TERM=rxvt-unicode PATH=(custom, user) LANG=en_US.UTF-8 SHELL=/bin/bash ProcFB: ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.2.0-32-generic root=/dev/mapper/hostname-root ro splash quiet video=vesa:off vga=normal vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-3.2.0-32-generic N/A linux-backports-modules-3.2.0-32-generic N/A linux-firmware 1.79.1 RfKill: Error: [Errno 2] No such file or directory SourcePackage: linux UdevDb: Error: [Errno 2] No such file or directory UpgradeStatus: Upgraded to precise on 2012-09-24 (37 days ago) UserAsoundrc: # Select PulseAudio as the default sound device pcm.!default { type pulse } dmi.bios.date: 11/16/2010 dmi.bios.vendor: American Megatrends Inc. dmi.bios.version: 0502 dmi.board.asset.tag: To Be Filled By O.E.M. dmi.board.name: P6X58D-E 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.:bvr0502:bd11/16/2010:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKComputerINC.:rnP6X58D-E: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/1073648/+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