lockmgr kernel panics with 4.6 on suspend

Hi,

after upgrading my Dell Latitude C600 to 4.6, I get kernel panics 
(lockmgr, not exclusive lock holder) whenever I try to suspend the 
machine. I've seen them happen either when suspending, or when resuming.

Something must have changed between 4.5 and 4.6; a kernel compiled from 
an identical config file could suspend/resume fine under 4.5

Here's a backtrace, and attached are my dmesg and kernel config file 
(gzipped).

Please let me know if there's any other information I can provide!


[root@ras02: /usr/src/sys/compile/KERNEL-1.39] gdb -k kernel.debug 
/var/crash/vmcore.1
GNU gdb 4.18 (FreeBSD)
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GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain 
conditions.
Type "show copying" to see the conditions.
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This GDB was configured as "i386-unknown-freebsd"...
IdlePTD at phsyical address 0x004ba000
initial pcb at physical address 0x003c2000
panicstr: from debugger
panic messages:
---
panic: lockmgr: pid 617, not exclusive lock holder 0 unlocking
panic: from debugger
Uptime: 3m41s
/dev/vmmon: Module vmmon: unloaded

dumping to dev #ad/0x20001, offset 524584
dump ata0: resetting devices .. done
255 254 253 252 251 250 249 248 247 246 245 244 243 242 241 240 239 238 
237 236 235 234 233 232 231 230 229 228 227 226 225 224 223 222 221 220 
219 218 217 216 215 214 213 212 211 210 209 208 207 206 205 204 203 202 
201 200 199 198 197 196 195 194 193 192 191 190 189 188 187 186 185 184 
183 182 181 180 179 178 177 176 175 174 173 172 171 170 169 168 167 166 
165 164 163 162 161 160 159 158 157 156 155 154 153 152 151 150 149 148 
147 146 145 144 143 142 141 140 139 138 137 136 135 134 133 132 131 130 
129 128 127 126 125 124 123 122 121 120 119 118 117 116 115 114 113 112 
111 110 109 108 107 106 105 104 103 102 101 100 99 98 97 96 95 94 93 92 
91 90 89 88 87 86 85 84 83 82 81 80 79 78 77 76 75 74 73 72 71 70 69 68 
67 66 65 64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49 48 47 46 45 44 
43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 22 21 20 
19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
---
#0  dumpsys () at ../../kern/kern_shutdown.c:487
487             if (dumping++) {
(kgdb) bt
#0  dumpsys () at ../../kern/kern_shutdown.c:487
#1  0xc0195a38 in boot (howto=260) at ../../kern/kern_shutdown.c:316
#2  0xc0195e85 in panic (fmt=0xc0303ce4 "from debugger") at 
../../kern/kern_shutdown.c:595
#3  0xc013f37d in db_panic (addr=-1070769619, have_addr=0, count=-1, 
modif=0xcde3fd7c "")
     at ../../ddb/db_command.c:435
#4  0xc013f31b in db_command (last_cmdp=0xc03746d8, cmd_table=0xc0374518,
     aux_cmd_tablep=0xc03b30d8) at ../../ddb/db_command.c:333
#5  0xc013f3e2 in db_command_loop () at ../../ddb/db_command.c:457
#6  0xc014159b in db_trap (type=3, code=0) at ../../ddb/db_trap.c:71
#7  0xc02d57cc in kdb_trap (type=3, code=0, regs=0xcde3fe84)
     at ../../i386/i386/db_interface.c:158
#8  0xc02e2994 in trap (frame={tf_fs = -965607408, tf_es = 16, tf_ds = 
6815760, tf_edi = 0,
       tf_esi = 256, tf_ebp = -840696116, tf_isp = -840696144, tf_ebx = 
-1070521824,
       tf_edx = -1070290065, tf_ecx = 32, tf_eax = 18, tf_trapno = 3, 
tf_err = 0,
       tf_eip = -1070769619, tf_cs = 8, tf_eflags = 582, tf_esp = 
-1070290081,
       tf_ss = -1070517509}) at ../../i386/i386/trap.c:584
#9  0xc02d5a2d in Debugger (msg=0xc03132fb "panic") at machine/cpufunc.h:67
#10 0xc0195e7c in panic (fmt=0xc0312220 "lockmgr: pid %d, not %s %d 
unlocking")
     at ../../kern/kern_shutdown.c:593
#11 0xc018fcf0 in lockmgr (lkp=0xc1540020, flags=6, interlkp=0x0, 
p=0xcc1d5080)
     at ../../kern/kern_lock.c:383
#12 0xc01c221f in vfs_unbusy (mp=0xc1540000, p=0xcc1d5080) at 
../../kern/vfs_subr.c:244
#13 0xc01c5b26 in sync (p=0xcc1d5080, uap=0xcde3ff80) at 
../../kern/vfs_syscalls.c:582
#14 0xc02e324e in syscall2 (frame={tf_fs = 47, tf_es = 47, tf_ds = 47, 
tf_edi = -1077936668,
       tf_esi = -1077936676, tf_ebp = -1077936760, tf_isp = -840695852, 
tf_ebx = 1,
       tf_edx = 0, tf_ecx = 0, tf_eax = 36, tf_trapno = 0, tf_err = 2, 
tf_eip = 134513444,
       tf_cs = 31, tf_eflags = 642, tf_esp = -1077936772, tf_ss = 47})
     at ../../i386/i386/trap.c:1167
#15 0xc02d66b5 in Xint0x80_syscall ()
#16 0x8048135 in ?? ()

(kgdb) up 11
#11 0xc018fcf0 in lockmgr (lkp=0xc1540020, flags=6, interlkp=0x0, 
p=0xcc1d5080)
     at ../../kern/kern_lock.c:383
383                                     panic("lockmgr: pid %d, not %s 
%d unlocking",
(kgdb) list
378
379             case LK_RELEASE:
380                     if (lkp->lk_exclusivecount != 0) {
381                             if (lkp->lk_lockholder != pid &&
382                                 lkp->lk_lockholder != LK_KERNPROC) {
383                                     panic("lockmgr: pid %d, not %s 
%d unlocking",
384                                         pid, "exclusive lock holder",
385                                         lkp->lk_lockholder);
386                             }
387                             if (lkp->lk_lockholder != LK_KERNPROC) {

-- 
Lars Eggert <[email protected]>           USC Information Sciences Institute