uvm_fault(0xfffffd8068d135d8, 0x0, 0, 1) -> e fatal page fault in supervisor mode trap type 6 code 0 rip ffffffff82d4e5f8 cs 8 rflags 10207 cr2 0 cpl 0 rsp ffff80003c44add0 gsbase 0xffff8000299edff0 kgsbase 0x0 panic: trap type 6, code=0, pc=ffffffff82d4e5f8 Starting stack trace... panic(ffffffff833a6996) at panic+0x1d0 sys/kern/subr_prf.c:229 kerntrap(ffff80003c44ad20) at kerntrap+0x30b alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b dt_ioctl_record_stop(ffff80000168e000) at dt_ioctl_record_stop+0x108 sys/dev/dt/dt_dev.c:586 dtclose(11e5f,81,2000,ffff8000363ec7f8) at dtclose+0x109 dt_pcb_purge sys/dev/dt/dt_dev.c:-1 [inline] dtclose(11e5f,81,2000,ffff8000363ec7f8) at dtclose+0x109 sys/dev/dt/dt_dev.c:232 spec_close(ffff80003c44aed0) at spec_close+0x466 sys/kern/spec_vnops.c:-1 VOP_CLOSE(fffffd805c925b40,81,fffffd80097fb478,ffff8000363ec7f8) at VOP_CLOSE+0x132 sys/kern/vfs_vops.c:156 vn_closefile(fffffd806b9d0168,ffff8000363ec7f8) at vn_closefile+0x12b vn_close sys/kern/vfs_vnops.c:292 [inline] vn_closefile(fffffd806b9d0168,ffff8000363ec7f8) at vn_closefile+0x12b sys/kern/vfs_vnops.c:615 fdrop(fffffd806b9d0168,ffff8000363ec7f8) at fdrop+0x121 sys/kern/kern_descrip.c:1280 closef(fffffd806b9d0168,ffff8000363ec7f8) at closef+0x192 sys/kern/kern_descrip.c:1264 fdfree(ffff8000363ec7f8) at fdfree+0x116 sys/kern/kern_descrip.c:1195 exit1(ffff8000363ec7f8,0,0,1) at exit1+0x576 sys/kern/kern_exit.c:215 sys_exit(ffff8000363ec7f8,ffff80003c44b240,ffff80003c44b190) at sys_exit+0x1a sys/kern/kern_exit.c:-1 syscall(ffff80003c44b240) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c44b240) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x779d2ea4a580, count: 242 End of stack trace. WARNING: SPL NOT LOWERED ON SYSCALL 263 320 EXIT 0 4 Stopped at savectx+0xae: movl $0,%gs:0x688 TID PID UID PRFLAGS PFLAGS CPU COMMAND 147689 70640 0 0 0x4000000 0 syz-executor * 30085 9301 0 0 0x4000000 1 syz-executor savectx() at savectx+0xae end of kernel end trace frame: 0x9cc39c2a610, count: 14 https://www.openbsd.org/ddb.html describes the minimum info required in bug reports. Insufficient info makes it difficult to find and fix bugs. ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic *cpu1: uvm_fault(0xfffffd8068d135d8, 0x0, 0, 1) -> e ddb{1}> trace savectx() at savectx+0xae end of kernel end trace frame: 0x9cc39c2a610, count: -1 ddb{1}> show registers rdi 0 rsi 0 rbp 0xffff80003c46f610 rbx 0 rdx 0 rcx 0xffff8000363ecfc0 rax 0x35 r8 0xffff80003c46f540 r9 0x1 r10 0x8b72b873abfc9b2f r11 0xe3b950b97be3a8d7 r12 0 r13 0 r14 0xffff8000363ecfc0 r15 0 rip 0xffffffff81feb3ee savectx+0xae cs 0x8 rflags 0x46 rsp 0xffff80003c46f590 ss 0x10 savectx+0xae: movl $0,%gs:0x688 ddb{1}> show proc PROC (syz-executor) tid=30085 pid=9301 tcnt=2 stat=onproc flags process=0 proc=4000000 runpri=50, usrpri=50, slppri=32, nice=20 wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0 forw=0xffffffffffffffff, list=0xffff8000fffeed10,0xffff8000363ecaa0 process=0xffff80003c4939f0 user=0xffff80003c46a000, vmspace=0xfffffd8068d139a8 estcpu=36, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 70640 294425 44119 0 2 0 syz-executor 70640 147689 44119 0 7 0x4000000 syz-executor 45413 114539 99544 0 2 0 syz-executor 9301 381854 67861 0 2 0 syz-executor * 9301 30085 67861 0 7 0x4000000 syz-executor 69059 368879 85877 0 2 0 syz-executor 69059 390694 85877 0 3 0x4000080 sbwait syz-executor 63553 517584 45057 0 3 0x80 nanoslp syz-executor 63553 256508 45057 0 3 0x4000080 sbwait syz-executor 63553 269773 45057 0 3 0x4000080 fsleep syz-executor 9312 41468 49151 0 2 0x2 syz-executor 74777 335565 0 0 3 0x14200 acct acct 67861 149747 49151 0 3 0x82 nanoslp syz-executor 88591 505057 49151 0 3 0x82 nanoslp syz-executor 45057 308140 49151 0 3 0x82 nanoslp syz-executor 44119 246897 49151 0 3 0x82 nanoslp syz-executor 42981 339441 1 0 3 0x100083 ttyin getty 99544 501621 49151 0 2 0x2 syz-executor 90546 106510 0 0 3 0x14200 bored sosplice 85877 200557 49151 0 3 0x82 nanoslp syz-executor 75061 157595 49151 0 3 0x82 nanoslp syz-executor 49151 129744 18022 0 3 0x82 kqread syz-executor 18022 254346 21235 0 3 0x10008a sigsusp ksh 21235 431248 11494 0 3 0x98 kqread sshd-session 11494 350195 63104 0 3 0x92 kqread sshd-session 63104 165583 1 0 3 0x88 kqread sshd 12610 53990 59633 74 3 0x1100092 bpf pflogd 59633 507514 1 0 3 0x80 sbwait pflogd 74064 415161 48884 73 3 0x1100090 kqread syslogd 48884 110940 1 0 3 0x100082 sbwait syslogd 69677 202345 1 0 3 0x100080 kqread resolvd 27307 390527 63859 77 3 0x100092 kqread dhcpleased 95432 407484 63859 77 3 0x100092 kqread dhcpleased 63859 225859 1 0 3 0x80 kqread dhcpleased 35237 428312 0 0 2 0x40014200 smr 18425 450854 0 0 2 0x14200 zerothread 67200 138291 0 0 3 0x14200 aiodoned aiodoned 52380 145920 0 0 3 0x14200 syncer update 96625 329598 0 0 3 0x14200 cleaner cleaner 32827 519233 0 0 3 0x14200 reaper reaper 29650 149054 0 0 3 0x14200 pgdaemon pagedaemon 10386 310740 0 0 3 0x14200 bored viomb 97567 416068 0 0 3 0x40014200 acpi0 acpi0 95322 67230 0 0 3 0x40014200 idle1 43941 501744 0 0 3 0x14200 bored softnet1 79777 500912 0 0 3 0x14200 netlock softnet0 77040 251748 0 0 2 0x40014200 systqmp 83960 407551 0 0 3 0x14200 bored systq 9116 203186 0 0 3 0x14200 tmoslp softclockmp 84576 183847 0 0 3 0x40014200 tmoslp softclock 97572 204571 0 0 3 0x40014200 idle0 1 496290 0 0 3 0x82 wait init 0 0 -1 0 3 0x10010200 scheduler swapper ddb{1}> show all locks Process 69059 (syz-executor) thread 0xffff8000fffef770 (390694) exclusive rwlock sbufrcv r = 0 (0xffff8000017134c0) #0 witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline] #0 witness_lock+0x5f1 sys/kern/subr_witness.c:1160 #1 rw_do_enter_write+0x419 sys/kern/kern_rwlock.c:320 #2 sblock+0xb6 sys/kern/uipc_socket2.c:536 #3 soreceive+0x27d sys/kern/uipc_socket.c:870 #4 recvit+0x40b sys/kern/uipc_syscalls.c:1078 #5 sys_recvmmsg+0x410 sys/kern/uipc_syscalls.c:969 #6 syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] #6 syscall+0xbd4 sys/arch/amd64/amd64/trap.c:746 #7 Xsyscall+0x128 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10262 11090K 12487K 166960K 17642 0 pcb 17 18K 24K 166960K 928 0 rtable 208 12K 14K 166960K 1315 0 pf 40 18K 82K 166960K 493 0 ifaddr 39 8K 9K 166960K 309 0 ifgroup 57 2K 2K 166960K 556 0 sysctl 4 1K 9K 166960K 98 0 counters 74 37K 38K 166960K 788 0 ioctlops 0 0K 4K 166960K 2678 0 iov 1 4K 32K 166960K 445 0 mount 1 1K 1K 166960K 1 0 log 0 0K 0K 166960K 4 0 vnodes 1614 101K 101K 166960K 6280 0 UFS quota 1 32K 32K 166960K 1 0 UFS mount 5 36K 36K 166960K 5 0 shm 2 1K 9K 166960K 56 0 VM map 2 1K 1K 166960K 2 0 sem 12 0K 0K 166960K 300 0 dirhash 12 2K 2K 166960K 81 0 ACPI 1692 195K 286K 166960K 12470 0 file desc 17 61K 240K 166960K 4216 0 sigio 0 0K 0K 166960K 83 0 proc 72 115K 164K 166960K 1545 0 subproc 72 4K 4K 166960K 271 0 NFS srvsock 1 0K 0K 166960K 1 0 NFS daemon 1 16K 16K 166960K 1 0 ip_moptions 0 0K 0K 166960K 625 0 in_multi 74 5K 7K 166960K 515 0 ether_multi 1 0K 0K 166960K 36 0 mrt 2 0K 0K 166960K 23 0 ISOFS mount 1 32K 32K 166960K 1 0 MSDOSFS mount 1 16K 16K 166960K 1 0 ttys 295 1314K 1314K 166960K 295 0 exec 0 0K 1K 166960K 1461 0 fusefs mount 1 32K 32K 166960K 1 0 pfkey data 0 0K 0K 166960K 7 0 tdb 3 0K 0K 166960K 3 0 VM swap 8 62K 64K 166960K 10 0 UVM amap 236 159K 182K 166960K 39151 0 UVM aobj 131 7K 7K 166960K 138 0 pinsyscall 42 84K 102K 166960K 5945 0 memdesc 1 4K 4K 166960K 1 0 crypto data 1 1K 1K 166960K 1 0 ip6_options 0 0K 0K 166960K 238 0 NDP 13 0K 1K 166960K 236 0 temp 80 8656K 8908K 166960K 166254 0 kqueue 13 20K 30K 166960K 808 0 SYN cache 2 8K 16K 166960K 3 0 ddb{1}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle plcache 128 26 0 0 1 0 1 1 0 8 0 rtpcb 120 518 0 515 4 3 1 3 0 8 0 rtentry 176 453 0 378 5 0 5 5 0 8 0 unpcb 144 3624 0 3605 21 17 4 6 0 8 3 syncache 336 28 0 28 6 6 0 1 0 8 0 tcpqe 32 7 0 7 4 4 0 1 0 8 0 tcpcb 736 1503 0 1497 25 23 2 7 0 8 1 arp 136 49 0 38 1 0 1 1 0 8 0 inpcb 328 4752 0 4739 37 35 2 15 0 8 0 nd6 144 69 0 56 1 0 1 1 0 8 0 pkpcb 40 31 0 31 7 7 0 1 0 8 0 kcovpl 48 30 0 22 1 0 1 1 0 8 0 mppekey 1024 2 0 2 2 2 0 1 0 8 0 ppxss 1192 291 0 288 6 5 1 1 0 8 0 pppxif 1504 19 0 19 7 7 0 1 0 8 0 pfstscr 40 2 0 2 1 1 0 1 0 8 0 pffrag 232 59 0 55 1 0 1 1 0 482 0 pffrnode 88 56 0 52 1 0 1 1 0 8 0 pffrent 40 239 0 234 1 0 1 1 0 8 0 pfosfp 40 1428 0 1428 5 5 0 5 0 8 0 pfosfpen 112 1428 0 1428 21 21 0 21 0 8 0 pfrktable 1344 15 0 15 5 5 0 1 0 8 0 pfanchor 1288 2 0 2 1 1 0 1 0 8 0 pftag 88 1 0 1 1 1 0 1 0 8 0 pfstitem 24 209 0 147 1 0 1 1 0 8 0 pfstkey 128 211 0 149 3 0 3 3 0 8 0 pfstate 384 209 0 148 9 1 8 9 0 8 0 pfrule 1344 24 0 19 2 1 1 2 0 8 0 rttmr 136 4 0 4 4 4 0 1 0 8 0 art_heap8 4096 4 0 0 4 0 4 4 0 8 0 art_heap4 256 2139 0 1811 59 34 25 50 0 8 0 art_table 40 2143 0 1811 9 2 7 9 0 8 0 art_node 32 449 0 385 2 0 2 2 0 8 0 sysvmsgpl 40 15 0 10 2 1 1 1 0 8 0 semupl 112 5 0 5 4 4 0 1 0 8 0 semapl 112 292 0 282 1 0 1 1 0 8 0 shmpl 112 135 0 7 4 0 4 4 0 8 0 dirhash 1024 64 0 47 3 0 3 3 0 8 0 dino2pl 256 9464 0 7903 98 0 98 98 0 8 0 ffsino 296 9464 0 7903 121 0 121 121 0 8 0 nchpl 144 14979 0 13216 66 0 66 66 0 8 0 rtmask 32 43 0 41 9 8 1 1 0 8 0 uvmvnodes 80 5926 0 0 121 0 121 121 0 8 0 vnodes 216 5926 0 0 330 0 330 330 0 8 0 namei 1024 57144 0 57144 6 5 1 3 0 8 1 percpumem 16 409 0 357 1 0 1 1 0 8 0 pfiaddrpl 120 3 0 3 1 1 0 1 0 8 0 kstatmem 264 358 0 328 8 5 3 3 0 8 0 acpiwqpl 32 1 0 1 1 0 1 1 1 8 1 scsiplug 72 21 0 21 6 6 0 1 0 8 0 scxspl 216 103143 0 103142 16 15 1 8 1 8 0 plimitpl 152 1119 0 1102 1 0 1 1 0 8 0 sigapl 424 4492 0 4443 9 2 7 7 0 8 0 knotepl 120 885 0 0 25 0 25 25 0 8 0 kqueuepl 224 1771 0 1762 20 19 1 5 0 8 0 pipepl 344 699 0 669 18 15 3 9 0 8 0 fdescpl 528 4457 0 4426 3 0 3 3 0 8 0 filepl 160 34258 0 34032 57 37 20 21 0 8 8 lockfpl 104 1741 0 1739 2 1 1 2 0 8 0 lockfspl 48 694 0 692 1 0 1 1 0 8 0 sessionpl 144 60 0 51 1 0 1 1 0 8 0 pgrppl 48 149 0 132 1 0 1 1 0 8 0 ucredpl 104 6780 0 6766 1 0 1 1 0 8 0 zombiepl 144 5084 0 5082 2 1 1 1 0 8 0 processpl 1232 4492 0 4443 7 2 5 5 0 8 0 procpl 664 11003 0 10949 8 2 6 7 0 8 0 sosppl 168 17 0 17 7 7 0 1 0 8 0 sockpl 752 9356 0 9321 106 95 11 24 0 8 7 mcl64k 65536 25 0 0 3 0 3 3 0 8 0 mcl16k 16384 2 0 0 1 0 1 1 0 8 0 mcl12k 12288 1 0 0 1 0 1 1 0 8 0 mcl9k 9216 2 0 0 1 0 1 1 0 8 0 mcl8k 8192 5 0 0 1 0 1 1 0 8 0 mcl4k 4096 129 0 0 16 0 16 16 0 8 0 mcl2k2 2112 1 0 0 1 0 1 1 0 8 0 mcl2k 2048 154 0 0 12 0 12 12 0 8 0 mtagpl 96 11 0 0 1 0 1 1 0 8 0 mbufpl 256 1201 0 0 74 0 74 74 0 8 0 bufpl 280 42026 0 35883 441 1 440 440 0 8 0 anonpl 32 11758 0 0 95 0 95 95 0 246 0 amapchunkpl 152 133463 0 132954 62 35 27 32 0 158 4 amappl16 200 16430 0 16397 82 68 14 26 0 8 4 amappl15 192 2 0 2 1 1 0 1 0 8 0 amappl14 184 187 0 175 1 0 1 1 0 8 0 amappl13 176 6 0 6 3 3 0 1 0 8 0 amappl12 168 5473 0 5443 3 1 2 2 0 8 0 amappl11 160 56 0 39 1 0 1 1 0 8 0 amappl10 152 8 0 8 2 2 0 1 0 8 0 amappl9 144 254 0 253 2 1 1 1 0 8 0 amappl8 136 27 0 24 1 0 1 1 0 8 0 amappl7 128 168 0 155 1 0 1 1 0 8 0 amappl6 120 443 0 439 1 0 1 1 0 8 0 amappl5 112 229 0 219 1 0 1 1 0 8 0 amappl4 104 395 0 374 1 0 1 1 0 8 0 amappl3 96 23885 0 23791 8 5 3 4 0 8 0 amappl2 88 4834 0 4756 2 0 2 2 0 8 0 amappl1 80 29646 0 29047 16 1 15 16 0 8 0 amappl 88 37337 0 37173 5 0 5 5 0 92 0 dma16384 16384 1 0 1 1 1 0 1 0 8 0 dma4096 4096 2 0 2 2 2 0 1 0 8 0 dma1024 1024 2 0 1 1 0 1 1 0 8 0 dma512 512 1 0 1 1 1 0 1 0 8 0 dma256 256 10 0 10 4 4 0 1 0 8 0 dma128 128 255 0 255 2 2 0 1 0 8 0 dma64 64 6 0 6 1 1 0 1 0 8 0 dma32 32 7 0 7 1 1 0 1 0 8 0 dma16 16 18 0 17 1 0 1 1 0 8 0 aobjpl 72 137 0 7 3 0 3 3 0 8 0 uaddrrnd 24 4457 0 4426 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 4457 0 4426 1 0 1 1 0 8 0 vmmpekpl 168 34085 0 34025 3 0 3 3 0 8 0 vmmpepl 168 284566 0 282566 134 35 99 111 0 357 0 vmsppl 488 4456 0 4426 6 1 5 5 0 8 0 rwobjpl 80 79931 0 72932 155 6 149 153 0 8 0 pdppl 4096 8922 0 8852 140 66 74 84 0 8 4 pvpl 32 19753 0 0 159 0 159 159 0 265 0 pmappl 256 4456 0 4426 3 0 3 3 0 8 0 extentpl 40 45 0 27 1 0 1 1 0 8 0 phpool 112 462 0 144 10 0 10 10 0 8 0 ddb{1}> machine ddbcpu 0 Stopped at x86_ipi_db+0x27: addq $0x8,%rsp x86_ipi_db(ffffffff837c9ff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:134 [inline] __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 sys/kern/kern_lock.c:165 softintr_dispatch(2) at softintr_dispatch+0x125 sys/kern/kern_softintr.c:83 dosoftint(2) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:847 Xsofttty() at Xsofttty+0x27 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0x2c kd_curproc sys/dev/kcov.c:584 [inline] __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0x2c sys/dev/kcov.c:153 __mp_lock(ffffffff83965ea8) at __mp_lock+0x1a3 __mp_lock_spin sys/kern/kern_lock.c:134 [inline] __mp_lock(ffffffff83965ea8) at __mp_lock+0x1a3 sys/kern/kern_lock.c:165 intr_handler(ffff80003c4811f0,ffff800000079a80) at intr_handler+0xe9 sys/arch/amd64/amd64/intr.c:559 Xintr_ioapic_edge23_untramp() at Xintr_ioapic_edge23_untramp+0x18f __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:134 [inline] __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 sys/kern/kern_lock.c:165 vn_ioctl(fffffd806fbcb0a0,80044b02,ffff80003c481400,ffff8000363ec560) at vn_ioctl+0x4d sys/kern/vfs_vnops.c:514 sys_ioctl(ffff8000363ec560,ffff80003c4815e0,ffff80003c481530) at sys_ioctl+0x674 sys/kern/sys_generic.c:-1 end trace frame: 0xffff80003c4815d0, count: 0 ddb{0}> trace x86_ipi_db(ffffffff837c9ff0) at x86_ipi_db+0x27 sys/arch/amd64/amd64/db_interface.c:394 x86_ipi_handler() at x86_ipi_handler+0xd9 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:134 [inline] __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 sys/kern/kern_lock.c:165 softintr_dispatch(2) at softintr_dispatch+0x125 sys/kern/kern_softintr.c:83 dosoftint(2) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:847 Xsofttty() at Xsofttty+0x27 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0x2c kd_curproc sys/dev/kcov.c:584 [inline] __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0x2c sys/dev/kcov.c:153 __mp_lock(ffffffff83965ea8) at __mp_lock+0x1a3 __mp_lock_spin sys/kern/kern_lock.c:134 [inline] __mp_lock(ffffffff83965ea8) at __mp_lock+0x1a3 sys/kern/kern_lock.c:165 intr_handler(ffff80003c4811f0,ffff800000079a80) at intr_handler+0xe9 sys/arch/amd64/amd64/intr.c:559 Xintr_ioapic_edge23_untramp() at Xintr_ioapic_edge23_untramp+0x18f __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 __mp_lock_spin sys/kern/kern_lock.c:134 [inline] __mp_lock(ffffffff83965ea8) at __mp_lock+0x192 sys/kern/kern_lock.c:165 vn_ioctl(fffffd806fbcb0a0,80044b02,ffff80003c481400,ffff8000363ec560) at vn_ioctl+0x4d sys/kern/vfs_vnops.c:514 sys_ioctl(ffff8000363ec560,ffff80003c4815e0,ffff80003c481530) at sys_ioctl+0x674 sys/kern/sys_generic.c:-1 syscall(ffff80003c4815e0) at syscall+0xbd4 mi_syscall sys/sys/syscall_mi.h:176 [inline] syscall(ffff80003c4815e0) at syscall+0xbd4 sys/arch/amd64/amd64/trap.c:746 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x7827fcf0da0, count: -16 ddb{0}> machine ddbcpu 1 Stopped at savectx+0xae: movl $0,%gs:0x688 savectx() at savectx+0xae end of kernel end trace frame: 0x9cc39c2a610, count: 14 ddb{1}> trace savectx() at savectx+0xae end of kernel end trace frame: 0x9cc39c2a610, count: -1