Date: Tue, 8 Sep 2009 11:13:02 +0200 From: Attilio Rao <attilio@freebsd.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: freebsd-emulation@freebsd.org, pluknet <pluknet@gmail.com>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: acquiring duplicate lock of same type: "ftlk" Message-ID: <3bbf2fe10909080213i588493darf8dd1e1ff768cb0a@mail.gmail.com> In-Reply-To: <20090908091114.GH47688@deviant.kiev.zoral.com.ua> References: <a31046fc0908270158l63b103a7v6c9fd1b7be54d3ed@mail.gmail.com> <a31046fc0909071115td2d5309na5738a44402feaa9@mail.gmail.com> <20090908091114.GH47688@deviant.kiev.zoral.com.ua>
next in thread | previous in thread | raw e-mail | index | archive | help
2009/9/8 Kostik Belousov <kostikbel@gmail.com>: > On Mon, Sep 07, 2009 at 10:15:48PM +0400, pluknet wrote: >> 2009/8/27 pluknet <pluknet@gmail.com>: >> > Hi. >> > >> > Got it on FreeBSD 9.0-CURRENT while been running in Xorg, don't know >> > where exactly. >> > >> > Acquiring duplicate lock of same type: "ftlk" >> > 1st ftlk @ /usr/src/sys/modules/linux/../../compat/linux/linux_futex.c:177 >> > 2nd ftlk @ /usr/src/sys/modules/linux/../../compat/linux/linux_futex.c:203 >> > KDB: stack backtrace: >> > db_trace_self_wrapper(c07fd8ea,ea393b58,c060a145,c05fac1b,c08007b2,...) >> > at db_trace_self_wrapper+0x26 >> > kdb_backtrace(c05fac1b,c08007b2,c0b49757,c58ead20,ea393bb4,...) at >> > kdb_backtrace+0x29 >> > _witness_debugger(c08007b2,c0b49793,c0b49757,cb,0,...) at _witness_debugger+0x25 >> > witness_checkorder(c9bba780,9,c0b49757,cb,0,...) at witness_checkorder+0x469 >> > _sx_xlock(c9bba780,0,c0b49757,cb,0,...) at _sx_xlock+0x85 >> > futex_get0(c0609f8c,c09cc7a8,c9ac7764,c09cc7a8,c084df3c,...) at futex_get0+0x116 >> > linux_sys_futex(c9ac76c0,ea393cf8,ea393d18,ea393d1c,c0b4cf40,...) at >> > linux_sys_futex+0x6f >> > syscall(ea393d38) at syscall+0x2b4 >> > Xint0x80_syscall() at Xint0x80_syscall+0x20 >> > --- syscall (240, Linux ELF, linux_sys_futex), eip = 0x28799533, esp = >> > 0xbfbfc0cc, ebp = 0x4000001 --- >> > >> > > From what dchagin@ told me, the LOR is unavoidable since he has to > acquire two sx locks of the same name. On the other hand, second sx lock > is not visible to any thread except the current one, so the LOR should > be innocent. > >> >> This time seeing this LOR again but with another one just before. >> 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" >> [...] >> >> I'm running head from 08/26. >> There were recent changes in pseudofs. Could it be fixed? >> Looks like it's connected to running firefox3 with linprocfs (for adobe flash). > > 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. Attilio -- Peace can only be achieved by understanding - A. Einstein
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?3bbf2fe10909080213i588493darf8dd1e1ff768cb0a>