Re: panic: Duplicate free of item 0xc5862800 from zone 0xc55f8580(NAMEI)

On Sat, 26 Mar 2005, Robert Watson wrote:

> Got the following panic while doing a buildworld on a dual xeon (quad
> logical processor) system today, using 6-CURRENT source from today.

Actually, it looks like this is a false positive -- a race introduced in
local code because the debugging code to check for multiple frees (etc) 
was getting called after mutexes/etc were released, so raced against
real-world re-allocation.

Robert N M Watson


> 
> Robert N M Watson
> 
> Slab at 0xc5857200, freei 2 = 0.
> panic: Duplicate free of item 0xc5862800 from zone 0xc55f8580(NAMEI)
> 
> cpuid = 1
> KDB: enter: panic
> [thread pid 10534 tid 100207 ]
> Stopped at      kdb_enter+0x2b: nop     
> db> trace
> Tracing pid 10534 tid 100207 td 0xc5e27000
> kdb_enter(c08317e5) at kdb_enter+0x2b
> panic(c084b549,c5862800,c55f8580,c0839cfb,c084b52d) at panic+0x127
> uma_dbg_free(c55f8580,0,c5862800) at uma_dbg_free+0x110
> uma_zfree_arg(c55f8580,c5862800,0) at uma_zfree_arg+0xf4
> namei(ebb3fbdc,c0626abe,c5e27000,c5e27000,c5e27000) at namei+0x245
> vn_open_cred(ebb3fbdc,ebb3fcdc,1a4,c5ddec80,3) at vn_open_cred+0x278
> vn_open(ebb3fbdc,ebb3fcdc,1a4,3,c0626abe) at vn_open+0x1e
> kern_open(c5e27000,8418900,0,8001,1b6) at kern_open+0xb6
> open(c5e27000,ebb3fd14,3,b,202) at open+0x1a
> syscall(2f,2f,bfbf002f,0,0) at syscall+0x213
> Xint0x80_syscall() at Xint0x80_syscall+0x1f
> --- syscall (5, FreeBSD ELF32, open), eip = 0x82d0e27, esp = 0xbfbfe2fc,
> ebp = 0xbfbfe318 ---
> db> show lockedvnods
> Locked vnodes
> 
> 0xc61819fc: tag ufs, type VREG
>     usecount 1, writecount 0, refcount 4 mountedhere 0
>     flags ()
>     v_object 0xc6174738 ref 0 pages 5
>      lock type ufs: EXCL (count 1) by thread 0xc5e27a10 (pid 10541)
>         ino 2028972, on dev ar0s1e
> 
> 0xc6b5fd50: tag ufs, type VREG
>     usecount 1, writecount 0, refcount 3 mountedhere 0
>     flags ()
>     v_object 0xc76d3528 ref 0 pages 1
>      lock type ufs: EXCL (count 1) by thread 0xc624aa10 (pid 10538)
>         ino 2028317, on dev ar0s1e
> 
> 
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