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Date: Mon, 24 Jan 2011 15:23:47 GMT
From: Olivier Certner <olivier.freebsd@free.fr>
To: freebsd-gnats-submit@FreeBSD.org
Subject: LOR between (ufs) vfs_mount.c and (devfs) ffs_vfsops.c
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>Number:         154266
>Category:       kern
>Synopsis:       LOR between (ufs) vfs_mount.c and (devfs) ffs_vfsops.c
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          closed
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Jan 24 15:30:09 UTC 2011
>Closed-Date:    Mon Jan 24 21:16:39 UTC 2011
>Last-Modified:  Mon Jan 24 22:10:10 UTC 2011
>Originator:     Olivier Certner
>Release:        9.0-CURRENT-201101
>Organization:
Private
>Environment:
FreeBSD 9.0-CURRENT-201101 #0: Mon Jan  3 22:15:39 UTC 2011 root@farrell.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC amd64
>Description:
This LOR appears when mounting a USB key (I think the slice had a UFS filesystem, but not completely sure). It doesn't seem to have been reported in any other PR.

lock order reversal:
 1st 0xfffffe0003e6b818 ufs (ufs) @ /usr/src/sys/kern/vfs_mount.c:1210
 2nd 0xfffffe00166f3638 devfs (devfs) @ /usr/src/sys/ufs/ffs/ffs_vfsops.c:1266
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
kdb_backtrace() at kdb_backtrace+0x37
_witness_debugger() at _witness_debugger+0x2e
witness_checkorder() at witness_checkorder+0x807
__lockmgr_args() at __lockmgr_args+0xd42
vop_stdlock() at vop_stdlock+0x39
VOP_LOCK1_APV() at VOP_LOCK1_APV+0x9b
_vn_lock() at _vn_lock+0x47
ffs_flushfiles() at ffs_flushfiles+0xb5
ffs_unmount() at ffs_unmount+0x70
dounmount() at dounmount+0x2dc
unmount() at unmount+0x28e
syscallenter() at syscallenter+0x1aa
syscall() at syscall+0x4c
Xfast_syscall() at Xfast_syscall+0xe2
--- syscall (22, FreeBSD ELF64, unmount), rip = 0x800b6c67c, rsp = 0x7fffffffeaa8, rbp = 0x7fffffffebc0 ---

>How-To-Repeat:
Mount some USB key with a UFS filesystem on it.
>Fix:
None.

>Release-Note:
>Audit-Trail:
State-Changed-From-To: open->closed 
State-Changed-By: brucec 
State-Changed-When: Mon Jan 24 21:16:02 UTC 2011 
State-Changed-Why:  
Known LOR - see http://sources.zabbadoz.net/freebsd/lor.html . 

http://www.freebsd.org/cgi/query-pr.cgi?pr=154266 

From: Olivier Certner <olivier.freebsd@free.fr>
To: brucec@freebsd.org
Cc: freebsd-bugs@freebsd.org,
 bug-followup@freebsd.org
Subject: Re: kern/154266: LOR between (ufs) vfs_mount.c and (devfs) ffs_vfsops.c
Date: Mon, 24 Jan 2011 23:01:06 +0100

 	Didn't know this site. Yes, the LOR seems very similar to LOR #276 (except 
 that there is no call to 'softdep_flushfiles' in my backtrace). One of the 
 LORs tagged #254 is also pretty close.
 
 	Still, I'm surprised that you closed this PR, since the abovementioned LORs 
 are all in the 'unknown' state, meaning (at least to me) they have not being 
 investigated and are potentially harmful. If this is the current policy for 
 those, I'll live with that, although I find it rather strange.
 
 	Thanks for your time,
 
 		Olivier Certner
>Unformatted:
