Here's the part that looks important; the whole dmesg is in the attachment. Thanks [ 761.730488] dnone_free_ramge: nblks = 0, trunc = 1, len = 18446744073709551615, blkshift = 0 [ 761.730542] dnode_free_range: nblks == 0, len == 18446744073709551615 , off=0 [ 761.730543] range_tree_clear: size == 0 [ 761.730605] VERIFY(size != 0) failed [ 761.730625] PANIC at range_tree.c:307:range_tree_find_impl() [ 761.730653] Showing stack for process 23913 [ 761.730656] CPU: 31 PID: 23913 Comm: receive_writer Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 761.730657] Hardware name: Supermicro SSG-6038R-E1CR16L/X10DRH-iT, BIOS 2.0 12/17/2015 [ 761.730658] Call Trace: [ 761.730668] dump_stack+0x6d/0x8e [ 761.730679] spl_dumpstack+0x42/0x50 [spl] [ 761.730684] spl_panic+0xc8/0x110 [spl] [ 761.730690] ? fbcon_cursor+0x13e/0x1c0 [ 761.730695] ? atomic_notifier_call_chain+0x1a/0x20 [ 761.730700] ? vt_console_print+0x240/0x410 [ 761.730705] ? up+0x32/0x50 [ 761.730708] ? console_unlock+0x2a1/0x560 [ 761.730767] range_tree_find_impl+0x88/0x90 [zfs] [ 761.730769] ? printk+0x52/0x6e [ 761.730810] range_tree_clear+0x54/0x70 [zfs] [ 761.730843] dnode_free_range+0x15b/0x720 [zfs] [ 761.730874] dmu_object_free+0x75/0xc0 [zfs] [ 761.730904] dmu_free_long_object+0x9f/0xc0 [zfs] [ 761.730934] receive_freeobjects.isra.12+0x7a/0x100 [zfs] [ 761.730963] receive_writer_thread+0x6d2/0xa60 [zfs] [ 761.730965] ? set_curr_task_fair+0x2b/0x60 [ 761.730970] ? spl_kmem_free+0x33/0x40 [spl] [ 761.730973] ? kfree+0x162/0x180 [ 761.731001] ? receive_free.isra.13+0xc0/0xc0 [zfs] [ 761.731006] thread_generic_wrapper+0x74/0x90 [spl] [ 761.731008] kthread+0x121/0x140 [ 761.731012] ? __thread_exit+0x20/0x20 [spl] [ 761.731014] ? kthread_create_worker_on_cpu+0x70/0x70 [ 761.731018] ret_from_fork+0x35/0x40 [ 967.430681] INFO: task txg_quiesce:4049 blocked for more than 120 seconds. [ 967.430739] Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 967.430785] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 967.430836] txg_quiesce D 0 4049 2 0x80000000 [ 967.430840] Call Trace: [ 967.430853] __schedule+0x24e/0x880 [ 967.430858] schedule+0x2c/0x80 [ 967.430875] cv_wait_common+0x11e/0x140 [spl] [ 967.430885] ? wait_woken+0x80/0x80 [ 967.430893] __cv_wait+0x15/0x20 [spl] [ 967.431010] txg_quiesce_thread+0x2cb/0x3d0 [zfs] [ 967.431078] ? txg_delay+0x1b0/0x1b0 [zfs] [ 967.431088] thread_generic_wrapper+0x74/0x90 [spl] [ 967.431093] kthread+0x121/0x140 [ 967.431099] ? __thread_exit+0x20/0x20 [spl] [ 967.431102] ? kthread_create_worker_on_cpu+0x70/0x70 [ 967.431107] ret_from_fork+0x35/0x40 [ 967.431140] INFO: task zfs:23834 blocked for more than 120 seconds. [ 967.431184] Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 967.431229] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 967.431279] zfs D 0 23834 23831 0x80000080 [ 967.431282] Call Trace: [ 967.431286] __schedule+0x24e/0x880 [ 967.431290] schedule+0x2c/0x80 [ 967.431298] cv_wait_common+0x11e/0x140 [spl] [ 967.431303] ? wait_woken+0x80/0x80 [ 967.431310] __cv_wait+0x15/0x20 [spl] [ 967.431367] dmu_recv_stream+0xa51/0xef0 [zfs] [ 967.431438] zfs_ioc_recv_impl+0x306/0x1100 [zfs] [ 967.431487] ? dbuf_rele+0x36/0x40 [zfs] [ 967.431555] zfs_ioc_recv_new+0x33d/0x410 [zfs] [ 967.431564] ? spl_kmem_alloc_impl+0xe5/0x1a0 [spl] [ 967.431571] ? spl_vmem_alloc+0x19/0x20 [spl] [ 967.431584] ? nv_alloc_sleep_spl+0x1f/0x30 [znvpair] [ 967.431590] ? nv_mem_zalloc.isra.0+0x2e/0x40 [znvpair] [ 967.431596] ? nvlist_xalloc.part.2+0x50/0xb0 [znvpair] [ 967.431660] zfsdev_ioctl+0x451/0x610 [zfs] [ 967.431672] do_vfs_ioctl+0xa8/0x630 [ 967.431677] ? __audit_syscall_entry+0xbc/0x110 [ 967.431682] ? syscall_trace_enter+0x1da/0x2d0 [ 967.431685] SyS_ioctl+0x79/0x90 [ 967.431688] do_syscall_64+0x73/0x130 [ 967.431693] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 967.431696] RIP: 0033:0x7f4c273385d7 [ 967.431698] RSP: 002b:00007ffed780e068 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 967.431701] RAX: ffffffffffffffda RBX: 0000000000005a46 RCX: 00007f4c273385d7 [ 967.431702] RDX: 00007ffed780e080 RSI: 0000000000005a46 RDI: 0000000000000006 [ 967.431704] RBP: 00007ffed780e080 R08: 00007f4c2760de20 R09: 0000000000000000 [ 967.431705] R10: 000055dc5929b010 R11: 0000000000000246 R12: 00007ffed78116b0 [ 967.431707] R13: 0000000000000006 R14: 000055dc592a2f10 R15: 000000000000000c [ 967.431722] INFO: task receive_writer:23913 blocked for more than 120 seconds. [ 967.431771] Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 967.431816] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 967.431867] receive_writer D 0 23913 2 0x80000080 [ 967.431870] Call Trace: [ 967.431874] __schedule+0x24e/0x880 [ 967.431878] schedule+0x2c/0x80 [ 967.431886] spl_panic+0xfa/0x110 [spl] [ 967.431892] ? atomic_notifier_call_chain+0x1a/0x20 [ 967.431902] ? vt_console_print+0x240/0x410 [ 967.431909] ? up+0x32/0x50 [ 967.431913] ? console_unlock+0x2a1/0x560 [ 967.431980] range_tree_find_impl+0x88/0x90 [zfs] [ 967.431985] ? printk+0x52/0x6e [ 967.432047] range_tree_clear+0x54/0x70 [zfs] [ 967.432102] dnode_free_range+0x15b/0x720 [zfs] [ 967.432152] dmu_object_free+0x75/0xc0 [zfs] [ 967.432200] dmu_free_long_object+0x9f/0xc0 [zfs] [ 967.432250] receive_freeobjects.isra.12+0x7a/0x100 [zfs] [ 967.432300] receive_writer_thread+0x6d2/0xa60 [zfs] [ 967.432306] ? set_curr_task_fair+0x2b/0x60 [ 967.432312] ? spl_kmem_free+0x33/0x40 [spl] [ 967.432320] ? kfree+0x162/0x180 [ 967.432366] ? receive_free.isra.13+0xc0/0xc0 [zfs] [ 967.432375] thread_generic_wrapper+0x74/0x90 [spl] [ 967.432378] kthread+0x121/0x140 [ 967.432384] ? __thread_exit+0x20/0x20 [spl] [ 967.432387] ? kthread_create_worker_on_cpu+0x70/0x70 [ 967.432391] ret_from_fork+0x35/0x40 [ 1088.260832] INFO: task txg_quiesce:4049 blocked for more than 120 seconds. [ 1088.260885] Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 1088.260931] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1088.260982] txg_quiesce D 0 4049 2 0x80000000 [ 1088.260985] Call Trace: [ 1088.260992] __schedule+0x24e/0x880 [ 1088.260996] schedule+0x2c/0x80 [ 1088.261007] cv_wait_common+0x11e/0x140 [spl] [ 1088.261012] ? wait_woken+0x80/0x80 [ 1088.261020] __cv_wait+0x15/0x20 [spl] [ 1088.261095] txg_quiesce_thread+0x2cb/0x3d0 [zfs] [ 1088.261163] ? txg_delay+0x1b0/0x1b0 [zfs] [ 1088.261171] thread_generic_wrapper+0x74/0x90 [spl] [ 1088.261174] kthread+0x121/0x140 [ 1088.261180] ? __thread_exit+0x20/0x20 [spl] [ 1088.261182] ? kthread_create_worker_on_cpu+0x70/0x70 [ 1088.261187] ret_from_fork+0x35/0x40 [ 1088.261211] INFO: task zfs:23834 blocked for more than 120 seconds. [ 1088.261255] Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 1088.261300] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1088.261350] zfs D 0 23834 23831 0x80000080 [ 1088.261353] Call Trace: [ 1088.261357] __schedule+0x24e/0x880 [ 1088.261361] schedule+0x2c/0x80 [ 1088.261370] cv_wait_common+0x11e/0x140 [spl] [ 1088.261374] ? wait_woken+0x80/0x80 [ 1088.261381] __cv_wait+0x15/0x20 [spl] [ 1088.261437] dmu_recv_stream+0xa51/0xef0 [zfs] [ 1088.261511] zfs_ioc_recv_impl+0x306/0x1100 [zfs] [ 1088.261558] ? dbuf_rele+0x36/0x40 [zfs] [ 1088.261627] zfs_ioc_recv_new+0x33d/0x410 [zfs] [ 1088.261636] ? spl_kmem_alloc_impl+0xe5/0x1a0 [spl] [ 1088.261643] ? spl_vmem_alloc+0x19/0x20 [spl] [ 1088.261651] ? nv_alloc_sleep_spl+0x1f/0x30 [znvpair] [ 1088.261657] ? nv_mem_zalloc.isra.0+0x2e/0x40 [znvpair] [ 1088.261662] ? nvlist_xalloc.part.2+0x50/0xb0 [znvpair] [ 1088.261726] zfsdev_ioctl+0x451/0x610 [zfs] [ 1088.261732] do_vfs_ioctl+0xa8/0x630 [ 1088.261737] ? __audit_syscall_entry+0xbc/0x110 [ 1088.261741] ? syscall_trace_enter+0x1da/0x2d0 [ 1088.261744] SyS_ioctl+0x79/0x90 [ 1088.261747] do_syscall_64+0x73/0x130 [ 1088.261752] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 [ 1088.261755] RIP: 0033:0x7f4c273385d7 [ 1088.261757] RSP: 002b:00007ffed780e068 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 1088.261759] RAX: ffffffffffffffda RBX: 0000000000005a46 RCX: 00007f4c273385d7 [ 1088.261761] RDX: 00007ffed780e080 RSI: 0000000000005a46 RDI: 0000000000000006 [ 1088.261762] RBP: 00007ffed780e080 R08: 00007f4c2760de20 R09: 0000000000000000 [ 1088.261764] R10: 000055dc5929b010 R11: 0000000000000246 R12: 00007ffed78116b0 [ 1088.261765] R13: 0000000000000006 R14: 000055dc592a2f10 R15: 000000000000000c [ 1088.261776] INFO: task receive_writer:23913 blocked for more than 120 seconds. [ 1088.261825] Tainted: P OE 4.15.0-99-generic #100-Ubuntu [ 1088.261870] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 1088.261921] receive_writer D 0 23913 2 0x80000080 [ 1088.261924] Call Trace: [ 1088.261928] __schedule+0x24e/0x880 [ 1088.261931] schedule+0x2c/0x80 [ 1088.261940] spl_panic+0xfa/0x110 [spl] [ 1088.261944] ? atomic_notifier_call_chain+0x1a/0x20 [ 1088.261954] ? vt_console_print+0x240/0x410 [ 1088.261958] ? up+0x32/0x50 [ 1088.261961] ? console_unlock+0x2a1/0x560 [ 1088.262031] range_tree_find_impl+0x88/0x90 [zfs] [ 1088.262036] ? printk+0x52/0x6e [ 1088.262099] range_tree_clear+0x54/0x70 [zfs] [ 1088.262153] dnode_free_range+0x15b/0x720 [zfs] [ 1088.262202] dmu_object_free+0x75/0xc0 [zfs] [ 1088.262250] dmu_free_long_object+0x9f/0xc0 [zfs] [ 1088.262300] receive_freeobjects.isra.12+0x7a/0x100 [zfs] [ 1088.262350] receive_writer_thread+0x6d2/0xa60 [zfs] [ 1088.262354] ? set_curr_task_fair+0x2b/0x60 [ 1088.262361] ? spl_kmem_free+0x33/0x40 [spl] [ 1088.262367] ? kfree+0x162/0x180 [ 1088.262413] ? receive_free.isra.13+0xc0/0xc0 [zfs] [ 1088.262420] thread_generic_wrapper+0x74/0x90 [spl] [ 1088.262425] kthread+0x121/0x140 [ 1088.262430] ? __thread_exit+0x20/0x20 [spl] [ 1088.262433] ? kthread_create_worker_on_cpu+0x70/0x70 [ 1088.262437] ret_from_fork+0x35/0x40