kern/40755: Hang on mounting immediately after newfs

[scotte%warped.com@localhost]

>Number:         40755
>Category:       kern
>Synopsis:       newfs, mount -o log in fast succession hangs kernel
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Feb 25 14:40:00 +0000 2009
>Originator:     Scott Ellis
>Release:        NetBSD 5.99.6
>Organization:
        
>Environment:
        
        
System: NetBSD intrepid 5.99.6 NetBSD 5.99.6 (INTREPID.P5W) #0: Thu Jan 8 
16:04:32 PST 2009 
scotte@intrepid:/nbu/source/netbsd/src/obj.amd64/nbu/source/netbsd/src/sys/arch/amd64/compile/INTREPID.P5W
 amd64
Architecture: x86_64
Machine: amd64
>Description:
        
Performing a newfs with a large number of inodes, FFS2, then immediately
attempting to mount that disk with -o log results in a kernel hang (cannot
break into DDB, etc.).  This is on a USB attached drive. Witness:

intrepid# newfs -O 2 -b 65536 -i 65536 /dev/rsd0a
/dev/rsd0a: 286188.8MB (586114640 sectors) block size 65536, fragment size 8192
        using 79 cylinder groups of 3622.69MB, 57963 blks, 57856 inodes.
super-block backups (for fsck_ffs -b #) at:
256, 7419520, 14838784, 22258048, 29677312, 37096576, 44515840, 51935104,
...............................................................................
intrepid# !mount
mount -o log /dev/sd0a /mounts/umass

It's not clear if the large inode value, FFS2, USB, or log is the culprit.

After the hang, the system can reboot and successfully mount the filesystem,
so it's not something specific to the on-disk configuration it seems.

The disk is identified as:

umass0 at uhub5 port 2 configuration 1 interface 0
umass0: Generic External, rev 2.00/2.02, addr 4
umass0: using SCSI over Bulk-Only
scsibus0 at umass0: 2 targets, 1 lun per target
sd0 at scsibus0 target 0 lun 0: <Generic, External, 2.02> disk fixed
sd0: 279 GB, 16383 cyl, 16 head, 63 sec, 512 bytes/sect x 586114704 sectors

>How-To-Repeat:
        
newfs -O 2 -b 65536 -i 65536 /dev/rsd0a
mount -o log /dev/sd0a /mounts/umass

>Fix:
        

>Unformatted: