New Lock Order Reversal in 12.0?

[Anindya Mukherjee]

Hi, I'm running 12.0-current and noticed a LOR message from WITNESS which I couldn't find a report about. I looked at http://sources.zabbadoz.net/freebsd/lor.html, among other places.

system details:
root at triskelion:~ # uname -a
FreeBSD triskelion 12.0-CURRENT FreeBSD 12.0-CURRENT #0 r311461: Thu Jan  5 22:46:38 UTC 2017     root at releng3.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64
root at triskelion:~ # freebsd-version
12.0-CURRENT


WITNESS report:
lock order reversal:
 1st 0xfffff8002e8049a0 ufs (ufs) @ /usr/src/sys/kern/vfs_subr.c:2598
 2nd 0xfffffe01e7ce9b40 bufwait (bufwait) @ /usr/src/sys/ufs/ffs/ffs_vnops.c:277
 3rd 0xfffff8002ec7b9a0 ufs (ufs) @ /usr/src/sys/kern/vfs_subr.c:2598
stack backtrace:
#0 0xffffffff80aa6fd0 at witness_debugger+0x70
#1 0xffffffff80aa6ed3 at witness_checkorder+0xde3
#2 0xffffffff80a20c15 at __lockmgr_args+0x725
#3 0xffffffff80d06fc5 at ffs_lock+0xa5
#4 0xffffffff8101c0c0 at VOP_LOCK1_APV+0xe0
#5 0xffffffff80b1a6aa at _vn_lock+0x9a
#6 0xffffffff80b0ac94 at vget+0x64
#7 0xffffffff80afd19c at vfs_hash_get+0xcc
#8 0xffffffff80d02e5e at ffs_vgetf+0x3e
#9 0xffffffff80cf9787 at softdep_sync_buf+0xc37
#10 0xffffffff80d07c51 at ffs_syncvnode+0x2a1
#11 0xffffffff80d06e60 at ffs_fsync+0x20
#12 0xffffffff8101b110 at VOP_FSYNC_APV+0xe0
#13 0xffffffff80d0f2f0 at ufs_direnter+0x870
#14 0xffffffff80d18050 at ufs_makeinode+0x5c0
#15 0xffffffff80d13d7a at ufs_create+0x3a
#16 0xffffffff810199ca at VOP_CREATE_APV+0xda
#17 0xffffffff80b19f77 at vn_open_cred+0x2c7

This is based on the FreeBSD-12.0-CURRENT-amd64-20170105-r311461-memstick.img installer. Known issue?

It happened during a portsnap fetch. the filesystem is UFS with default mount options.