>Number: 51178
>Category: kern
>Synopsis: forced umount panics with wapbl
>Confidential: no
>Severity: critical
>Priority: low
>Responsible: kern-bug-people
>State: open
>Class: sw-bug
>Submitter-Id: net
>Arrival-Date: Sun May 29 08:55:00 +0000 2016
>Originator: Michael van Elst
>Release: NetBSD 7.99.29
>Organization:
>Environment:
System: NetBSD tazz 7.99.29 NetBSD 7.99.29 (TAZZ) #5: Sat May 28 08:36:59 CEST 2016 mlelstv@gossam:/home/netbsd-current/obj.amd64/home/netbsd-current/src/sys/arch/amd64/compile/TAZZ amd64
Architecture: x86_64
Machine: amd64
>Description:
An ISCSI device that was no longer responding was mounted with -o log.
When the system is rebooted, it fails to umount regularly and then tries
a forced umount which triggers
kernel diagnostic assertion "bp->b_freelist == -1" failed: file "/home/netbsd-curent/src/sys/kern/vfs_bio.c", line 334 double free of buffer? bp=0xfffffe811ca9b008, b_freelistindex=0
gdb shows the following backtrace:
#11 0xffffffff807b1d2d in binstailfree (dp=0xffffffff813f6b20 <bufqueues>,
bp=0xfffffe811ca9b008) at /home/netbsd-current/src/sys/kern/vfs_bio.c:333
#12 brelsel (bp=0xfffffe811ca9b008, set=<optimized out>)
at /home/netbsd-current/src/sys/kern/vfs_bio.c:1092
#13 0xffffffff807cf7e6 in wapbl_discard (wl=0xfffffe8116eefc08)
at /home/netbsd-current/src/sys/kern/vfs_wapbl.c:661
#14 0xffffffff807c985d in vclean (vp=vp@entry=0xfffffe811be41bd0)
at /home/netbsd-current/src/sys/kern/vfs_vnode.c:1032
#15 0xffffffff807cb45c in vrecycle (vp=vp@entry=0xfffffe811be41bd0)
at /home/netbsd-current/src/sys/kern/vfs_vnode.c:1099
#16 0xffffffff807bd42d in vflush (mp=mp@entry=0xfffffe8113de4008,
skipvp=skipvp@entry=0x0, flags=flags@entry=3)
at /home/netbsd-current/src/sys/kern/vfs_mount.c:525
#17 0xffffffff806ce0a5 in ffs_flushfiles (mp=mp@entry=0xfffffe8113de4008,
flags=flags@entry=2, l=l@entry=0xfffffe8117f6b0c0)
at /home/netbsd-current/src/sys/ufs/ffs/ffs_vfsops.c:1775
#18 0xffffffff806cebdf in ffs_unmount (mp=0xfffffe8113de4008,
mntflags=<optimized out>)
at /home/netbsd-current/src/sys/ufs/ffs/ffs_vfsops.c:1693
#19 0xffffffff807c0cd5 in VFS_UNMOUNT (mp=mp@entry=0xfffffe8113de4008,
a=a@entry=524288) at /home/netbsd-current/src/sys/kern/vfs_subr.c:1296
#20 0xffffffff807bd5dd in dounmount (mp=mp@entry=0xfffffe8113de4008,
flags=flags@entry=524288, l=l@entry=0xfffffe8117f6b0c0)
at /home/netbsd-current/src/sys/kern/vfs_mount.c:856
#21 0xffffffff807bd87b in vfs_unmount_forceone (l=0xfffffe8117f6b0c0)
at /home/netbsd-current/src/sys/kern/vfs_mount.c:953
#22 0xffffffff80119928 in cpu_reboot (howto=0, bootstr=bootstr@entry=0x0)
at /home/netbsd-current/src/sys/arch/amd64/amd64/machdep.c:659
#23 0xffffffff80758bd5 in sys_reboot (l=<optimized out>,
uap=0xfffffe8040ca6f00, retval=<optimized out>)
at /home/netbsd-current/src/sys/kern/kern_xxx.c:82
#24 0xffffffff8013cd65 in sy_call (rval=0xfffffe8040ca6eb0,
uap=0xfffffe8040ca6f00, l=0xfffffe8117f6b0c0,
sy=0xffffffff80e268e0 <sysent+4992>)
at /home/netbsd-current/src/sys/sys/syscallvar.h:65
#25 sy_invoke (code=208, rval=0xfffffe8040ca6eb0, uap=0xfffffe8040ca6f00,
l=0xfffffe8117f6b0c0, sy=0xffffffff80e268e0 <sysent+4992>)
at /home/netbsd-current/src/sys/sys/syscallvar.h:94
#26 syscall (frame=0xfffffe8040ca6f00)
at /home/netbsd-current/src/sys/arch/x86/x86/syscall.c:156
#27 0xffffffff80100731 in Xsyscall ()
>How-To-Repeat:
umount forcefully a filesystem mounted with -o log where the
device no longer responds.
You probably need some write operation in progress.
>Fix:
>Unformatted: