Re: kern/54541: kernel panic using "zfs diff"

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

The following reply was made to PR kern/54541; it has been noted by GNATS.

From: Patrick Welche <prlw1%cam.ac.uk@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/54541: kernel panic using "zfs diff"
Date: Thu, 12 Sep 2019 14:35:32 +0100

 On Wed, Sep 11, 2019 at 09:55:01AM +0000, Patrick Welche wrote:
 >  caused a freeze with nothing appearing on the console. Of course
 >  this box doesn't even have a serial header on its motherboard.
 
 Finally got there - I see your panic:
 
 panic: kernel diagnostic assertion "fdm != NULL" failed: file "../../../../kern/vfs_trans.c", line 166 mount 0x0 invalid
 cpu0: Begin traceback...
 vpanic() at netbsd:vpanic+0x160
 stge_eeprom_wait.isra.4() at netbsd:stge_eeprom_wait.isra.4
 fstrans_alloc_lwp_info() at netbsd:fstrans_alloc_lwp_info+0x283
 fstrans_start() at netbsd:fstrans_start+0x3f
 VOP_LOCK() at netbsd:VOP_LOCK+0x4c
 vn_lock() at netbsd:vn_lock+0xa1
 vn_rdwr() at netbsd:vn_rdwr+0x136
 write_record.part.1() at zfs:write_record.part.1+0x54
 diff_cb() at zfs:diff_cb+0x236
 traverse_visitbp() at zfs:traverse_visitbp+0x1b6
 traverse_visitbp() at zfs:traverse_visitbp+0x52b
 traverse_visitbp() at zfs:traverse_visitbp+0x52b
 traverse_visitbp() at zfs:traverse_visitbp+0x52b
 traverse_visitbp() at zfs:traverse_visitbp+0x52b
 traverse_visitbp() at zfs:traverse_visitbp+0x52b
 traverse_dnode() at zfs:traverse_dnode+0xda
 traverse_visitbp() at zfs:traverse_visitbp+0x8ab
 traverse_impl() at zfs:traverse_impl+0x16c
 traverse_dataset_resume() at zfs:traverse_dataset_resume+0x44
 dmu_diff() at zfs:dmu_diff+0x14c
 zfs_ioc_diff() at zfs:zfs_ioc_diff+0x42
 zfsdev_ioctl() at zfs:zfsdev_ioctl+0x265
 nb_zfsdev_ioctl() at zfs:nb_zfsdev_ioctl+0x38
 VOP_IOCTL() at netbsd:VOP_IOCTL+0x54
 vn_ioctl() at netbsd:vn_ioctl+0xa5
 sys_ioctl() at netbsd:sys_ioctl+0x5ab
 syscall() at netbsd:syscall+0x196
 --- syscall (number 54) ---
 
 and found a crash dump.
 
 (gdb) frame 4
 #4  fstrans_alloc_lwp_info (mp=mp@entry=0x0)
     at ../../../../kern/vfs_trans.c:383
 383             fstrans_debug_validate_mount(mp);
 (gdb) list
 378             /*
 379              * Attach the entry to the mount if its mnt_transinfo is valid380              */
 381     
 382             mutex_enter(&fstrans_mount_lock);
 383             fstrans_debug_validate_mount(mp);
 384             fmi = mp->mnt_transinfo;
 385             KASSERT(fmi != NULL);
 386             fli->fli_mount = mp;
 387             fli->fli_mountinfo = fmi;
 (gdb) print *mp
 Cannot access memory at address 0x0
 
 The back trace is what was in dmesg. I can't see zfs_anything() using gdb.