Bug 55175
| Summary: | [lor] LOR in select and poll | ||
|---|---|---|---|
| Product: | Base System | Reporter: | Kris Kennaway <kris> |
| Component: | kern | Assignee: | Alfred Perlstein <alfred> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | ||
| Priority: | Normal | ||
| Version: | 5.1-CURRENT | ||
| Hardware: | Any | ||
| OS: | Any | ||
Responsible Changed From-To: freebsd-bugs->alfred I'll look at this. Still getting this as of 04/09/2004 -- just wondering if any decision/progress has been made. On Sat, Apr 10, 2004 at 01:17:13PM -0500, Jon Noack wrote:
> Still getting this as of 04/09/2004 -- just wondering if any
> decision/progress has been made.
Consensus seems to be that it's not easy to fix.
Kris
State Changed From-To: open->feedback I haven't seen this in 6 or 7. Is it still an issue? State Changed From-To: feedback->closed This was fixed somewhere back in the mists of time |
Since upgrading the bento i386 package build machines to 5.1-CURRENT, the following two lock order reversals have been seen. lock order reversal 1st 0xc6c1c334 filedesc structure (filedesc structure) @ +/a/asami/portbuild/i386/src-client/sys/kern/sys_generic.c:902 2nd 0xc04aa120 Giant (Giant) @ /a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c:372 Stack backtrace: backtrace(c043d4af,c04aa120,c0439aa4,c0439aa4,c0434e3d) at backtrace+0x17 witness_lock(c04aa120,8,c0434e3d,174,1bc) at witness_lock+0x672 _mtx_lock_flags(c04aa120,0,c0434e3d,174,c043daba) at _mtx_lock_flags+0xba spec_poll(d8dddaf8,d8dddb18,c02d119c,d8dddaf8,c04939a0) at spec_poll+0x134 spec_vnoperate(d8dddaf8,c04939a0,c520b124,40,c675e300) at spec_vnoperate+0x18 vn_poll(c44c5e14,40,c675e300,c6222d10,c675e300) at vn_poll+0x3c selscan(c6222d10,d8dddb98,d8dddb88,6,4) at selscan+0x13e kern_select(c6222d10,6,bfbff5c0,0,0) at kern_select+0x36f select(c6222d10,d8dddd10,c0455899,3ee,5) at select+0x66 syscall(2f,2f,2f,8055050,bfbff5b8) at syscall+0x273 Xint0x80_syscall() at Xint0x80_syscall+0x1d --- syscall (93), eip = 0x280ccacc, esp = 0x2832eb68, ebp = 0x2832ebc0 --- Debugger("witness_lock") Stopped at Debugger+0x54: xchgl %ebx,in_Debugger.0 #8 0xc0290ed7 in witness_lock (lock=0xc04aa120, flags=8, file=0xc0434e3d "/a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c", line=372) at /a/asami/portbuild/i386/src-client/sys/kern/subr_witness.c:838 #9 0xc0261f4a in _mtx_lock_flags (m=0x0, opts=0, file=0xc04d17a8 "", line=-1068850912) at /a/asami/portbuild/i386/src-client/sys/kern/kern_mutex.c:334 #10 0xc0231154 in spec_poll (ap=0xd8dddaf8) at /a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c:372 #11 0xc0230648 in spec_vnoperate (ap=0x0) at /a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c:122 #12 0xc02d119c in vn_poll (fp=0x0, events=0, active_cred=0xc675e300, td=0x0) at vnode_if.h:537 #13 0xc02945ae in selscan (td=0xc6222d10, ibits=0xd8dddb98, obits=0xd8dddb88, nfd=6) at /a/asami/portbuild/i386/src-client/sys/sys/file.h:272 #14 0xc029412f in kern_select (td=0xc6222d10, nd=6, fd_in=0xbfbff5c0, fd_ou=0x0, fd_ex=0x0, tvp=0xd8dddcd4) at /a/asami/portbuild/i386/src-client/sys/kern/sys_generic.c:822 #15 0xc0293da6 in select (td=0x0, uap=0xd8dddd10) at /a/asami/portbuild/i386/src-client/sys/kern/sys_generic.c:726 #16 0xc03ef9b3 in syscall (frame= {tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = 134565968, tf_esi = -1077938760, tf_ebp = 674425792, +tf_isp = -656548492, tf_ebx = 0, tf_edx = -1077938752, tf_ecx = 0, tf_eax = 93, tf_trapno = 12, tf_err = 2, +tf_eip = 671926988, tf_cs = 31, tf_eflags = 534, tf_esp = 674425704, tf_ss = 47}) at /a/asami/portbuild/i386/src-client/sys/i386/i386/trap.c:1008 #17 0xc03dfbed in Xint0x80_syscall () at {standard input}:144 ---Can't read userspace from dump, or kernel process--- lock order reversal 1st 0xc6a69634 filedesc structure (filedesc structure) @ +/a/asami/portbuild/i386/src-client/sys/kern/sys_generic.c:1071 2nd 0xc04aa120 Giant (Giant) @ /a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c:372 Stack backtrace: backtrace(c043d4af,c04aa120,c0439aa4,c0439aa4,c0434e3d) at backtrace+0x17 witness_lock(c04aa120,8,c0434e3d,174,246) at witness_lock+0x672 _mtx_lock_flags(c04aa120,0,c0434e3d,174,c043daba) at _mtx_lock_flags+0xba spec_poll(d8dfcb44,d8dfcb64,c02d119c,d8dfcb44,c04939a0) at spec_poll+0x134 spec_vnoperate(d8dfcb44,c04939a0,c52cfa44,41,c6cfd280) at spec_vnoperate+0x18 vn_poll(c45dc880,41,c6cfd280,c5f7a4c0,c6cfd280) at vn_poll+0x3c pollscan(c5f7a4c0,d8dfcbd4,2,3e7,10) at pollscan+0xb0 poll(c5f7a4c0,d8dfcd10,c0455899,3ee,3) at poll+0x252 syscall(2f,2f,2f,0,2) at syscall+0x273 Xint0x80_syscall() at Xint0x80_syscall+0x1d #8 0xc0290ed7 in witness_lock (lock=0xc04aa120, flags=8, file=0xc0434e3d "/a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c", line=372) at /a/asami/portbuild/i386/src-client/sys/kern/subr_witness.c:838 #9 0xc0261f4a in _mtx_lock_flags (m=0x0, opts=0, file=0xc04d1818 "", line=-1068850912) at /a/asami/portbuild/i386/src-client/sys/kern/kern_mutex.c:334 #10 0xc0231154 in spec_poll (ap=0xd8dfcb44) at /a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c:372 #11 0xc0230648 in spec_vnoperate (ap=0x0) at /a/asami/portbuild/i386/src-client/sys/fs/specfs/spec_vnops.c:122 #12 0xc02d119c in vn_poll (fp=0x0, events=0, active_cred=0xc6cfd280, td=0x0) at vnode_if.h:537 #13 0xc0294c50 in pollscan (td=0xc5f7a4c0, fds=0xd8dfcbdc, nfd=2) at /a/asami/portbuild/i386/src-client/sys/sys/file.h:272 #14 0xc02948a2 in poll (td=0xc5f7a4c0, uap=0xd8dfcd10) at /a/asami/portbuild/i386/src-client/sys/kern/sys_generic.c:1001 #15 0xc03ef9b3 in syscall (frame= {tf_fs = 47, tf_es = 47, tf_ds = 47, tf_edi = 0, tf_esi = 2, tf_ebp = -1077940448, tf_isp = -656421516, +tf_ebx = 673224876, tf_edx = 139153408, tf_ecx = 137314336, tf_eax = 209, tf_trapno = 0, tf_err = 2, tf_eip = +672942388, tf_cs = 31, tf_eflags = 659, tf_esp = -1077940508, tf_ss = 47}) at /a/asami/portbuild/i386/src-client/sys/i386/i386/trap.c:1008 #16 0xc03dfbed in Xint0x80_syscall () at {standard input}:144 ---Can't read userspace from dump, or kernel process--- The original mail may be found here: http://docs.freebsd.org/cgi/getmsg.cgi?fetch=73697+0+current/freebsd-current Message-ID: <20030727233351.GB80934@rot13.obsecurity.org> rwatson replied with: > I've bumped into some similar problems -- it's a property of how we > current lock select(). We hold the file descriptor lock for the duration > of polling each object being "selected", and if any of those objects has > to grab a lock for any reason, it has to implicitly fall after the file > descriptor lock. I actually run into this in some of our MAC code, > because I need to grab a vnode lock to authorize polling the vnode using > VOP_POLL(), and since the vnode lock is a sleep lock, this generates a > WITNESS warning. Unfortunately, it's not immediately clear what a better > locking scheme would look like without going overboard on the fine-grained > side. We probably need to grab Giant before entering the select code > since it's highly likely something in there will require Giant -- it > reaches down into VFS, the device stuff, socket code, tc. How-To-Repeat: Unknown.