Fatal trap 12: page fault while in kernel mode cpuid = 0; apic id = 00 fault virtual address = 0x6dc fault code = supervisor read data, page not present instruction pointer = 0x20:0xffffffff80572e7f stack pointer = 0x28:0xffffff803e722530 frame pointer = 0x28:0xffffff803e722550 code segment = base 0x0, limit 0xfffff, type 0x1b = DPL 0, pres 1, long 1, def32 0, gran 1 processor eflags = interrupt enabled, resume, IOPL = 0 current process = 1030 (nfsd: service) [thread pid 1030 tid 100140 ] Stopped at prison_priv_check+0xff: movl 0x6dc(%rsi),%eax db> bt Tracing pid 1030 tid 100140 td 0xffffff00029ea000 prison_priv_check() at prison_priv_check+0xff priv_check_cred() at priv_check_cred+0x4c secpolicy_vnode_access() at secpolicy_vnode_access+0x28 zfs_zaccess() at zfs_zaccess+0x1d5 zfs_freebsd_access() at zfs_freebsd_access+0xd0 VOP_ACCESS_APV() at VOP_ACCESS_APV+0x44 nfsrv_access() at nfsrv_access+0xf3 nfsrv3_access() at nfsrv3_access+0x386 nfssvc_program() at nfssvc_program+0x1fb svc_run_internal() at svc_run_internal+0x6d2 svc_thread_start() at svc_thread_start+0xb fork_exit() at fork_exit+0x118 fork_trampoline() at fork_trampoline+0xe --- trap 0xc, rip = 0x8006a0e1c, rsp = 0x7fffffffe6d8, rbp = 0x5 --- db> (kgdb) frame 12 #12 0xffffffff80572e7f in prison_priv_check (cred=0xffffff00168f5900, priv=334) at /usr/home/wxs/freebsd/src/head/sys/kern/kern_jail.c:3315 3315 switch (priv) { (kgdb) p priv $6 = 334 334 is PRIV_VFS_MOUNT_OWNER sys/kern/kern_jail.c: 3451 case PRIV_VFS_MOUNT_OWNER: 3452 if (cred->cr_prison->pr_allow & PR_ALLOW_MOUNT) 3453 return (0); 3454 else 3455 return (EPERM); (kgdb) p/x *cred $7 = {cr_ref = 0x1, cr_uid = 0x0, cr_ruid = 0x0, cr_svuid = 0x0, cr_ngroups = 0x1, cr_groups = {0x0 }, cr_rgid = 0x0, cr_svgid = 0x0, cr_uidinfo = 0x0, cr_ruidinfo = 0x0, cr_prison = 0x0, cr_vimage = 0x0, cr_flags = 0x0, cr_pspare = {0x0, 0x0}, cr_label = 0x0, cr_audit = {ai_auid = 0x0, ai_mask = {am_success = 0x0, am_failure = 0x0}, ai_termid = {at_port = 0x0, at_type = 0x0, at_addr = {0x0, 0x0, 0x0, 0x0}}, ai_asid = 0x0, ai_flags = 0x0}} (kgdb) cred->cr_prison is null?