Hello, I have two VMs, exporting some directories in one VM: # cat /etc/exports /mnt 192.168.1.0/24(ro,fsid=0,no_subtree_check,sync) /mnt/export 192.168.1.0/24(rw,no_root_squash,sync,no_wdelay,no_subtree_check) [...] And NFS mounting in the second VM: # grep nfs /proc/mounts server:/export /mnt/export nfs4 rw,relatime,vers=4.2,rsize=1048576,wsize=1048576,namlen=255, acregmin=1,acregmax=1,acdirmin=1,acdirmax=1,hard,nordirplus, proto=tcp,timeo=600,retrans=2,sec=sys,clientaddr=192.168.1.11, local_lock=none,addr=192.168.1.10 0 0 [...] If I keep some file descriptor open for several minutes in the second VM, for example by running this: # sleep 10m >/mnt/export/test Then result is that the NFS mount stops responding: the sleep process never finished but is "forever" stuck in (killable) D state, and any I/O attempt from other processes in /mnt/export never finish. It's always reproducible with this sleep command. To recover the mountpoint I need to reboot the second VM. Kernel version is 5.3.0-rc4 in both VMs. Also reproducible with 4.14.x and 4.19.x # ps aux|grep sleep root 2524 0.0 0.0 5900 688 pts/0 D 14:04 0:00 sleep 5m # grep -C100 nfs /proc/*/stack /proc/2524/stack:[<0>] nfs4_do_close+0x87d/0xb20 [nfsv4] /proc/2524/stack:[<0>] __put_nfs_open_context+0x297/0x4f0 [nfs] /proc/2524/stack:[<0>] nfs_file_release+0xbe/0xf0 [nfs] /proc/2524/stack-[<0>] __fput+0x1df/0x690 /proc/2524/stack-[<0>] task_work_run+0x123/0x1b0 /proc/2524/stack-[<0>] exit_to_usermode_loop+0x121/0x140 /proc/2524/stack-[<0>] do_syscall_64+0x2d1/0x370 /proc/2524/stack-[<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 -- /proc/561/stack-[<0>] __rpc_execute+0x692/0xb10 [sunrpc] /proc/561/stack-[<0>] rpc_run_task+0x45f/0x5d0 [sunrpc] /proc/561/stack:[<0>] nfs4_call_sync_sequence+0x12a/0x210 [nfsv4] /proc/561/stack:[<0>] _nfs4_proc_getattr+0x19a/0x200 [nfsv4] /proc/561/stack:[<0>] nfs4_proc_getattr+0xda/0x230 [nfsv4] /proc/561/stack:[<0>] __nfs_revalidate_inode+0x2ed/0x7a0 [nfs] /proc/561/stack:[<0>] nfs_do_access+0x605/0xd00 [nfs] /proc/561/stack:[<0>] nfs_permission+0x500/0x5e0 [nfs] /proc/561/stack-[<0>] inode_permission+0x2dd/0x3f0 /proc/561/stack-[<0>] link_path_walk.part.60+0x681/0xe40 /proc/561/stack-[<0>] path_lookupat.isra.63+0x1af/0x850 /proc/561/stack-[<0>] filename_lookup.part.79+0x165/0x360 /proc/561/stack-[<0>] vfs_statx+0xb9/0x140 /proc/561/stack-[<0>] __do_sys_newstat+0x77/0xd0 /proc/561/stack-[<0>] do_syscall_64+0x9a/0x370 /proc/561/stack-[<0>] entry_SYSCALL_64_after_hwframe+0x44/0xa9 In dmesg of second VM sometimes nfs complaints are seen: [ 386.362897] nfs: server xyz not responding, still trying Any ideas what's going wrong here...? -Tommi
