Bug 204330

Summary:	Lock order reversal in ffs_vnops.c:bufwait
Product:	Base System	Reporter:	liuw
Component:	kern	Assignee:	freebsd-bugs (Nobody) <bugs>
Status:	New ---
Severity:	Affects Only Me
Priority:	---
Version:	CURRENT
Hardware:	amd64
OS:	Any

Description liuw 2015-11-06 11:17:36 UTC

lock order reversal:
 1st 0xfffff8000514cd50 ufs (ufs) @ /usr/home/weil/freebsd/sys/kern/vfs_subr.c:2231
 2nd 0xfffffe007aa26b80 bufwait (bufwait) @ /usr/home/weil/freebsd/sys/ufs/ffs/ffs_vnops.c:263
 3rd 0xfffff8000d254240 ufs (ufs) @ /usr/home/weil/freebsd/sys/kern/vfs_subr.c:2231
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe0094c44e80
witness_checkorder() at witness_checkorder+0xe79/frame 0xfffffe0094c44f00
__lockmgr_args() at __lockmgr_args+0xd3b/frame 0xfffffe0094c44fb0
ffs_lock() at ffs_lock+0xa6/frame 0xfffffe0094c45000
VOP_LOCK1_APV() at VOP_LOCK1_APV+0x100/frame 0xfffffe0094c45030
_vn_lock() at _vn_lock+0x9a/frame 0xfffffe0094c450a0
vget() at vget+0x63/frame 0xfffffe0094c450f0
vfs_hash_get() at vfs_hash_get+0xcc/frame 0xfffffe0094c45140
ffs_vgetf() at ffs_vgetf+0x40/frame 0xfffffe0094c451d0
softdep_sync_buf() at softdep_sync_buf+0xad1/frame 0xfffffe0094c452b0
ffs_syncvnode() at ffs_syncvnode+0x256/frame 0xfffffe0094c45330
ffs_truncate() at ffs_truncate+0x6cd/frame 0xfffffe0094c45520
ufs_direnter() at ufs_direnter+0x7bb/frame 0xfffffe0094c455f0
ufs_makeinode() at ufs_makeinode+0x5f3/frame 0xfffffe0094c457b0
ufs_create() at ufs_create+0x2d/frame 0xfffffe0094c457d0
VOP_CREATE_APV() at VOP_CREATE_APV+0xf1/frame 0xfffffe0094c45800
vn_open_cred() at vn_open_cred+0x2f8/frame 0xfffffe0094c45970
kern_openat() at kern_openat+0x25c/frame 0xfffffe0094c45ae0
amd64_syscall() at amd64_syscall+0x2de/frame 0xfffffe0094c45bf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe0094c45bf0
--- syscall (499, FreeBSD ELF64, sys_openat), rip = 0x800b50c2a, rsp = 0x7fffffffe1a8, rbp = 0x7fffffffe280 ---