Re: kern/52728: "mount -u /dev/ /" triggers kernel panic

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

The following reply was made to PR kern/52728; it has been noted by GNATS.

From: Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: tsutsui%ceres.dti.ne.jp@localhost
Subject: Re: kern/52728: "mount -u /dev/ /" triggers kernel panic
Date: Thu, 16 Nov 2017 23:35:08 +0900

 Note the panic also occurs on NetBSD/amd64 7.1 GENERIC.
 
 --- logged via serial console ---
 
 > boot -s
 14221568+654648+594632 [1027320+719300]=0x116d090
 Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
     2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017
     The NetBSD Foundation, Inc.  All rights reserved.
 Copyright (c) 1982, 1986, 1989, 1991, 1993
     The Regents of the University of California.  All rights reserved.
 
 NetBSD 7.1 (GENERIC.201703111743Z)
 total memory = 4029 MB
 avail memory = 3894 MB
 kern.module.path=/stand/amd64/7.1/modules
 RTC BIOS diagnostic error 0x11<memory_size>
 mainbus0 (root)
 
 [..snip..]
 
 boot device: wd0
 root on wd0a dumps on wd0b
 root file system type: ffs
 Enter pathname of shell or RETURN for /bin/sh:
 Terminal type is vt100.
 We recommend that you create a non-root account and use su(1) for root access.
 # mount -u /dev/ /
 mount_ffs: uvm_fault(0xfffffe81075f2a10, 0x0, 1) -> e
 fatal page fault in supervisor mode
 trap type 6 code 0 rip ffffffff80339a1b cs 8 rflags 10212 cr2 18 ilevel 0 rsp fffffe8040582d60
 curlwp 0xfffffe8119ecd640 pid 9.1 lowest kstack 0xfffffe80405802c0
 kernel: page fault trap, code=0
 Stopped in pid 9.1 (mount_ffs) at       netbsd:ffs_mount+0xbf:  cmpq    %rax,18(
 %rcx)
 db{0}> bt
 ffs_mount() at netbsd:ffs_mount+0xbf
 VFS_MOUNT() at netbsd:VFS_MOUNT+0x34
 do_sys_mount() at netbsd:do_sys_mount+0x485
 sys___mount50() at netbsd:sys___mount50+0x33
 syscall() at netbsd:syscall+0x9a
 --- syscall (number 410) ---
 7f7ff7083caa:
 db{0}> 
 
 ---