Date: Wed, 9 Sep 2009 14:55:41 -0400 From: John Baldwin <jhb@freebsd.org> To: freebsd-current@freebsd.org Cc: Attilio Rao <attilio@freebsd.org>, freebsd-emulation@freebsd.org, pluknet <pluknet@gmail.com> Subject: Re: acquiring duplicate lock of same type: "ftlk" Message-ID: <200909091455.42039.jhb@freebsd.org> In-Reply-To: <a31046fc0909081242v7e1b8f98t72a6df8b9d37a960@mail.gmail.com> References: <a31046fc0908270158l63b103a7v6c9fd1b7be54d3ed@mail.gmail.com> <3bbf2fe10909080213i588493darf8dd1e1ff768cb0a@mail.gmail.com> <a31046fc0909081242v7e1b8f98t72a6df8b9d37a960@mail.gmail.com>
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On Tuesday 08 September 2009 3:42:13 pm pluknet wrote:
> 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:
> >>> =A01st 0xc75365b8 pseudofs (pseudofs) @ /usr/src/sys/kern/vfs_lookup.=
c:497
> >>> =A02nd 0xc088ea3c allproc (allproc) @ /usr/src/sys/kern/kern_proc.c:2=
92
> >>> KDB: stack backtrace:
> >>> db_trace_self_wrapper(c07fd8ea,e82148e4,c060a145,c05fac1b,c08008bf,..=
=2E)
> >>> 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=20
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=20
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=20
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=20
linux_open+0x41
> >>> syscall(e8214d38) at syscall+0x2b4
> >>> Xint0x80_syscall() at Xint0x80_syscall+0x20
> >>> --- syscall (5, Linux ELF, linux_open), eip =3D 0x2889115e, esp =3D
> >>> 0xbfbfbd1c, ebp =3D 0xbfbfbd6c ---
> >>> acquiring duplicate lock of same type: "ftlk"
> >>> [...]
> >>
> >> The second LOR actually exposes the right order. It would be interesti=
ng
> >> 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.
> >
>=20
> 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 },
>=20
> 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"
>=20
> Something else?
What are the seen orders with "allproc"?
=2D-=20
John Baldwin
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