Date: Fri, 21 Aug 2009 14:05:13 -0400 (EDT) From: Rick Macklem <rmacklem@uoguelph.ca> To: "Rick C. Petty" <rick-freebsd2008@kiwi-computer.com> Cc: bzeeb+freebsd+lor@zabbadoz.net, current@freebsd.org Subject: Re: various vfs LORs Message-ID: <Pine.GSO.4.63.0908211402510.14428@muncher.cs.uoguelph.ca> In-Reply-To: <20090819175029.GA90205@keira.kiwi-computer.com> References: <20090819161817.GA89704@keira.kiwi-computer.com> <20090819175029.GA90205@keira.kiwi-computer.com>
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On Wed, 19 Aug 2009, Rick C. Petty wrote: > > This LOR doesn't seem to be reported anywhere: > >> lock order reversal: >> 1st 0xffffff00046de7f8 nfs (nfs) @ /usr/src/sys/kern/vfs_syscalls.c:4097 >> 2nd 0xffffff80a5129968 bufwait (bufwait) @ /usr/src/sys/kern/vfs_bio.c:1835 >> 3rd 0xffffff00046de620 nfs (nfs) @ /usr/src/sys/nfsclient/nfs_node.c:161 >> KDB: stack backtrace: >> db_trace_self_wrapper() at db_trace_self_wrapper+0x2a >> _witness_debugger() at _witness_debugger+0x2e >> witness_checkorder() at witness_checkorder+0x81e >> __lockmgr_args() at __lockmgr_args+0xcf3 >> nfs_nget() at nfs_nget+0x1c9 >> nfs_readdirplusrpc() at nfs_readdirplusrpc+0x7cc >> nfs_doio() at nfs_doio+0x617 >> nfs_bioread() at nfs_bioread+0xa9f >> nfs_readdir() at nfs_readdir+0x85 >> kern_getdirentries() at kern_getdirentries+0x12e >> getdirentries() at getdirentries+0x23 >> syscall() at syscall+0x1af >> Xfast_syscall() at Xfast_syscall+0xe1 >> --- syscall (196, FreeBSD ELF64, getdirentries), rip = 0x8009d11dc, rsp = 0x7fffffffc3a8, rbp = 0x1 --- Since the 3rd one is locking a newly allocated nfs vnode (that isn't yet in the mount point list, etc), I don't think this will cause a problem and I don't see an easy way to avoid it. rick
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