Date: Tue, 8 Sep 2009 21:48:37 +0200 From: Attilio Rao <attilio@freebsd.org> To: pluknet <pluknet@gmail.com> Cc: freebsd-emulation@freebsd.org, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: acquiring duplicate lock of same type: "ftlk" Message-ID: <3bbf2fe10909081248w3a09c9a8ge3b6fa9de8b2d3e9@mail.gmail.com> In-Reply-To: <a31046fc0909081242v7e1b8f98t72a6df8b9d37a960@mail.gmail.com> References: <a31046fc0908270158l63b103a7v6c9fd1b7be54d3ed@mail.gmail.com> <a31046fc0909071115td2d5309na5738a44402feaa9@mail.gmail.com> <20090908091114.GH47688@deviant.kiev.zoral.com.ua> <3bbf2fe10909080213i588493darf8dd1e1ff768cb0a@mail.gmail.com> <a31046fc0909081242v7e1b8f98t72a6df8b9d37a960@mail.gmail.com>
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2009/9/8 pluknet <pluknet@gmail.com>:
> 2009/9/8 Attilio Rao <attilio@freebsd.org>:
>> 2009/9/8 Kostik Belousov <kostikbel@gmail.com>:
>>> On Mon, Sep 07, 2009 at 10:15:48PM +0400, pluknet wrote:
>>>> lock order reversal:
>>>> 1st 0xc75365b8 pseudofs (pseudofs) @ /usr/src/sys/kern/vfs_lookup.c:497
>>>> 2nd 0xc088ea3c allproc (allproc) @ /usr/src/sys/kern/kern_proc.c:292
>>>> KDB: stack backtrace:
>>>> db_trace_self_wrapper(c07fd8ea,e82148e4,c060a145,c05fac1b,c08008bf,...)
>>>> at db_trace_self_wrapper+0x26
>>>> kdb_backtrace(c05fac1b,c08008bf,c58eabe8,c58e30d0,e8214940,...) at
>>>> kdb_backtrace+0x29
>>>> _witness_debugger(c08008bf,c088ea3c,c07f981d,c58e30d0,c07f96f0,...) at
>>>> _witness_debugger+0x25
>>>> witness_checkorder(c088ea3c,1,c07f96f0,124,0,...) at witness_checkorder+0x839
>>>> _sx_slock(c088ea3c,0,c07f96f0,124,c73c4980,...) at _sx_slock+0x85
>>>> pfind(514,c72ba1a0,4,c07f8d78,c5fe1b40,...) at pfind+0x2f
>>>> pfs_visible(0,0,c07f042d,7c,c7536560,...) at pfs_visible+0x3a
>>>> pfs_lookup(e8214a40,c082715e,c7536560,c7536560,e8214bf8,...) at pfs_lookup+0x3dd
>>>> VOP_CACHEDLOOKUP_APV(c0843960,e8214a40,e8214bf8,e8214be4,c73c4e80,...)
>>>> at VOP_CACHEDLOOKUP_APV+0xc5
>>>> vfs_cache_lookup(e8214acc,c08087d0,c0875a00,200000,e8214bcc,...) at
>>>> vfs_cache_lookup+0xd6
>>>> VOP_LOOKUP_APV(c0843960,e8214acc,e8214bf8,1f1,e8214be4,...) at
>>>> VOP_LOOKUP_APV+0xe5
>>>> lookup(e8214bcc,c5fd1800,0,c5,c5ef77f8,...) at lookup+0x63b
>>>> namei(e8214bcc,c5c1500d,3f3,e8214c20,c5c1500d,...) at namei+0x57f
>>>> kern_alternate_path(c5fe1b40,c0b4921c,2879f478,0,e8214c74,...) at kern_alternate
>>>> _path+0x1cd
>>>> linux_emul_convpath(c5fe1b40,2879f478,0,e8214c74,0,...) at
>>>> linux_emul_convpath+0x3c
>>>> linux_open(c5fe1b40,e8214cf8,e8214d18,e8214d1c,c0b4b58c,...) at linux_open+0x41
>>>> syscall(e8214d38) at syscall+0x2b4
>>>> Xint0x80_syscall() at Xint0x80_syscall+0x20
>>>> --- syscall (5, Linux ELF, linux_open), eip = 0x2889115e, esp =
>>>> 0xbfbfbd1c, ebp = 0xbfbfbd6c ---
>>>> acquiring duplicate lock of same type: "ftlk"
>>>> [...]
>>>
>>> The second LOR actually exposes the right order. It would be interesting
>>> to look up the point where the other order is established.
>>
>> You would manually patch the witness static table with this order and
>> the opposite will show, when happening.
>>
>
> I've patched witness order table, and still no opposite case,
> nor any pseudofs related LORs at all.
> { "pseudofs", &lock_class_lockmgr },
> { "allproc", &lock_class_sx },
> { NULL, NULL },
>
> Seen orders with pseudofs:
> "ufs","pseudofs"
> "pseudofs","allproc"
> "pseudofs","process lock"
> "pseudofs","vnode interlock"
> "pseudofs","struct mount mtx"
> "pseudofs","UMA zone"
> "pseudofs","sleep mtxpool"
> "pseudofs","Name Cache"
> "pseudofs","vnode_free_list"
> "pseudofs","pfs_node"
> "pseudofs","pfs_vncache"
>
> Something else?
Probabilly it just takes time.
You should try to recreate conditions you did before to get this LOR.
Attilio
--
Peace can only be achieved by understanding - A. Einstein
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