witness: lock order reversal: 1st 0xffffffff82c75c58 &sched_lock (&sched_lock) 2nd 0xffff800021210980 &pr->ps_mtx (&pr->ps_mtx) lock order "&pr->ps_mtx"(mutex) -> "&sched_lock"(sched_lock) first seen at: #0 __mp_lock+0xa2 read_rflags machine/cpufunc.h:195 [inline] #0 __mp_lock+0xa2 intr_disable machine/cpufunc.h:216 [inline] #0 __mp_lock+0xa2 sys/kern/kern_lock.c:142 #1 donice+0x178 sys/kern/kern_resource.c:218 #2 syscall+0x5e2 mi_syscall sys/sys/syscall_mi.h:110 [inline] #2 syscall+0x5e2 sys/arch/amd64/amd64/trap.c:623 #3 Xsyscall+0x128 lock order "&sched_lock"(sched_lock) -> "&pr->ps_mtx"(mutex) first seen at: #0 mtx_enter+0x3e sys/kern/kern_lock.c:265 #1 single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] #1 single_thread_set+0x35a sys/kern/kern_sig.c:2155 #2 sigexit+0x90 sys/kern/kern_sig.c:1562 #3 postsig+0x4a9 sys/kern/kern_sig.c:1494 #4 userret+0x16e sys/kern/kern_sig.c:1987 #5 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #5 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #6 Xsyscall+0x128 Stopped at db_enter+0x1c: addq $0x8,%rsp ddb{1}> ddb{1}> set $lines = 0 ddb{1}> set $maxwidth = 0 ddb{1}> show panic the kernel did not panic ddb{1}> trace db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437 witness_checkorder(ffff800021210980,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2510 [inline] witness_checkorder(ffff800021210980,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1110 mtx_enter(ffff800021210970) at mtx_enter+0x3e sys/kern/kern_lock.c:265 single_thread_set(ffff800021225010,0,1) at single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] single_thread_set(ffff800021225010,0,1) at single_thread_set+0x35a sys/kern/kern_sig.c:2155 sigexit(ffff800021225010,6) at sigexit+0x90 sys/kern/kern_sig.c:1562 postsig(ffff800021225010,6,ffff800021297048) at postsig+0x4a9 sys/kern/kern_sig.c:1494 userret(ffff800021225010) at userret+0x16e sys/kern/kern_sig.c:1987 syscall(ffff800021297180) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff800021297180) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x5bd165ae3f0, count: -9 ddb{1}> show registers rdi 0x3 rsi 0xffffffff82c40e70 __sancov_gen_cov_switch_values.134 rbp 0xffff800021296d50 rbx 0x3 rdx 0x3fd rcx 0 rax 0x1 r8 0xffff800021296cc0 r9 0x8080808080808080 r10 0x5e43168c50c6ef5 r11 0x2a0abf5139f8a2c5 r12 0xfffffd8003a0d850 r13 0 r14 0xfffffd8003a059d0 r15 0xfffffd80031cabc0 rip 0xffffffff82131f9c db_enter+0x1c cs 0x8 rflags 0x246 rsp 0xffff800021296d40 ss 0x10 db_enter+0x1c: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.0) pid=417562 stat=onproc flags process=100000 proc=4002000 pri=32, usrpri=86, nice=20 forw=0xffffffffffffffff, list=0xffff800021225808,0xffffffff82d74600 process=0xffff800021210870 user=0xffff800021292000, vmspace=0xfffffd807d02d580 estcpu=36, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 55800 472769 61989 0 4 0x182000 syz-executor.0 *55800 417562 61989 0 7 0x4102000 syz-executor.0 61989 172772 72189 0 3 0x82 nanoslp syz-executor.0 72189 189858 93548 0 3 0x2000082 thrsleep syz-execprog 72189 444731 93548 0 3 0x6000082 thrsleep syz-execprog 72189 437240 93548 0 3 0x6000082 thrsleep syz-execprog 72189 335019 93548 0 3 0x6000082 thrsleep syz-execprog 72189 520666 93548 0 3 0x6000082 thrsleep syz-execprog 72189 297547 93548 0 3 0x6000082 thrsleep syz-execprog 72189 97606 93548 0 3 0x6000082 kqread syz-execprog 72189 359865 93548 0 3 0x6000082 thrsleep syz-execprog 72189 376358 93548 0 3 0x6000082 thrsleep syz-execprog 72189 504362 93548 0 3 0x6000082 wait syz-execprog 72189 444102 93548 0 3 0x6000082 thrsleep syz-execprog 93548 196697 79331 0 3 0x10008a sigsusp ksh 79331 82811 75740 0 3 0x9a kqread sshd 28671 113632 1 0 3 0x100083 ttyin getty 75740 390835 1 0 3 0x88 kqread sshd 83757 227607 19305 74 3 0x1100092 bpf pflogd 19305 426691 1 0 3 0x80 netio pflogd 1176 440322 3194 73 3 0x1100090 kqread syslogd 3194 520131 1 0 3 0x100082 netio syslogd 10721 274636 1 0 3 0x100080 kqread resolvd 69877 181511 48892 77 3 0x100092 kqread dhcpleased 9514 53435 48892 77 3 0x100092 kqread dhcpleased 48892 83510 1 0 3 0x80 kqread dhcpleased 71575 360670 0 0 3 0x14200 bored smr 17150 92423 0 0 7 0x14200 zerothread 22553 47965 0 0 3 0x14200 aiodoned aiodoned 35225 432701 0 0 3 0x14200 syncer update 14718 309003 0 0 3 0x14200 cleaner cleaner 56769 85716 0 0 3 0x14200 reaper reaper 54884 18936 0 0 3 0x14200 pgdaemon pagedaemon 82675 390937 0 0 3 0x14200 bored viomb 93218 50324 0 0 3 0x40014200 acpi0 acpi0 17391 303794 0 0 3 0x40014200 idle1 89683 365437 0 0 3 0x14200 bored softnet3 79218 76075 0 0 3 0x14200 bored softnet2 3827 131837 0 0 3 0x14200 bored softnet1 95137 137121 0 0 3 0x14200 bored softnet0 4876 41880 0 0 3 0x14200 bored systqmp 65262 293585 0 0 3 0x14200 bored systq 89894 456655 0 0 3 0x40014200 bored softclock 75276 371682 0 0 3 0x40014200 idle0 1 306284 0 0 3 0x82 wait init 0 0 -1 0 3 0x10200 scheduler swapper ddb{1}> show all locks CPU 1: exclusive sched_lock &sched_lock r = 0 (0xffffffff82c75c58) #0 witness_lock+0x447 #1 single_thread_set+0x179 sys/kern/kern_sig.c:2113 #2 sigexit+0x90 sys/kern/kern_sig.c:1562 #3 postsig+0x4a9 sys/kern/kern_sig.c:1494 #4 userret+0x16e sys/kern/kern_sig.c:1987 #5 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #5 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #6 Xsyscall+0x128 Process 55800 (syz-executor.0) thread 0xffff800021225010 (417562) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82d78a60) #0 witness_lock+0x447 #1 postsig+0x49e sys/kern/kern_sig.c:1500 #2 userret+0x16e sys/kern/kern_sig.c:1987 #3 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #3 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #4 Xsyscall+0x128 exclusive sched_lock &sched_lock r = 0 (0xffffffff82c75c58) #0 witness_lock+0x447 #1 single_thread_set+0x179 sys/kern/kern_sig.c:2113 #2 sigexit+0x90 sys/kern/kern_sig.c:1562 #3 postsig+0x4a9 sys/kern/kern_sig.c:1494 #4 userret+0x16e sys/kern/kern_sig.c:1987 #5 syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] #5 syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 #6 Xsyscall+0x128 ddb{1}> show malloc Type InUse MemUse HighUse Limit Requests Type Lim devbuf 10165 6458K 6458K 78643K 11243 0 pcb 13 8K 8K 78643K 13 0 rtable 80 2K 2K 78643K 138 0 pf 18 7K 10K 78643K 29 0 ifaddr 17 10K 10K 78643K 17 0 ifgroup 27 1K 1K 78643K 27 0 counters 46 34K 34K 78643K 46 0 ioctlops 0 0K 4K 78643K 1476 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 4 0 vnodes 1176 74K 74K 78643K 1192 0 UFS quota 1 32K 32K 78643K 1 0 UFS mount 5 36K 36K 78643K 5 0 shm 2 1K 1K 78643K 2 0 VM map 2 1K 1K 78643K 2 0 sem 2 0K 0K 78643K 2 0 dirhash 12 2K 2K 78643K 12 0 ACPI 1697 195K 286K 78643K 12548 0 file desc 4 9K 13K 78643K 25 0 proc 67 91K 103K 78643K 330 0 NFS srvsock 1 0K 0K 78643K 1 0 NFS daemon 1 16K 16K 78643K 1 0 in_multi 22 1K 1K 78643K 22 0 ether_multi 1 0K 0K 78643K 1 0 ISOFS mount 1 32K 32K 78643K 1 0 MSDOSFS mount 1 16K 16K 78643K 1 0 ttys 25 122K 122K 78643K 25 0 exec 0 0K 1K 78643K 290 0 tdb 3 0K 0K 78643K 3 0 pagedep 1 8K 8K 78643K 1 0 inodedep 1 32K 32K 78643K 1 0 newblk 1 0K 0K 78643K 1 0 VM swap 8 62K 64K 78643K 10 0 UVM amap 175 16K 16K 78643K 2921 0 UVM aobj 3 2K 2K 78643K 3 0 memdesc 1 4K 4K 78643K 1 0 crypto data 1 1K 1K 78643K 1 0 NDP 7 0K 0K 78643K 7 0 temp 1 5904K 5968K 78643K 3364 0 kqueue 12 18K 18K 78643K 25 0 SYN cache 2 16K 16K 78643K 2 0 ddb{1}> show all pools Name Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle plcache 128 22 0 0 1 0 1 1 0 8 0 rtpcb 120 19 0 16 1 0 1 1 0 8 0 rtentry 112 34 0 1 1 0 1 1 0 8 0 unpcb 144 35 0 20 1 0 1 1 0 8 0 syncache 304 5 0 5 1 0 1 1 0 8 1 tcpqe 32 206 0 206 1 1 0 1 0 8 0 tcpcb 808 8 0 5 1 0 1 1 0 8 0 arp 120 4 0 0 1 0 1 1 0 8 0 inpcb 368 37 0 31 1 0 1 1 0 8 0 nd6 136 3 0 0 1 0 1 1 0 8 0 pfosfp 40 1428 0 1005 5 0 5 5 0 8 0 pfosfpen 112 1428 0 714 21 0 21 21 0 8 0 pfstitem 24 10 0 0 1 0 1 1 0 8 0 pfstkey 128 10 0 0 1 0 1 1 0 8 0 pfstate 376 10 0 0 1 0 1 1 0 8 0 pfrule 1344 21 0 16 2 1 1 2 0 8 0 art_heap8 4096 1 0 0 1 0 1 1 0 8 0 art_heap4 256 144 0 0 9 0 9 9 0 8 0 art_table 32 145 0 0 2 0 2 2 0 8 0 art_node 16 33 0 3 1 0 1 1 0 8 0 dirhash 1024 17 0 0 3 0 3 3 0 8 0 dino2pl 256 1465 0 52 89 0 89 89 0 8 0 ffsino 272 1465 0 52 95 0 95 95 0 8 0 nchpl 144 1704 0 63 61 0 61 61 0 8 0 uvmvnodes 80 1479 0 0 31 0 31 31 0 8 0 vnodes 216 1479 0 0 83 0 83 83 0 8 0 namei 1024 5443 0 5443 2 0 2 2 0 8 2 percpumem 16 36 0 0 1 0 1 1 0 8 0 kstatmem 264 10 0 0 1 0 1 1 0 8 0 scxspl 216 6208 0 6208 3 2 1 2 1 8 1 plimitpl 152 28 0 19 1 0 1 1 0 8 0 sigapl 424 359 0 325 7 1 6 6 0 8 2 knotepl 120 66 0 0 2 0 2 2 0 8 0 kqueuepl 216 21 0 13 1 0 1 1 0 8 0 pipepl 320 115 0 108 2 0 2 2 0 8 1 fdescpl 496 342 0 325 4 0 4 4 0 8 1 filepl 152 1520 0 1450 4 0 4 4 0 8 1 lockfpl 104 6 0 4 1 0 1 1 0 8 0 lockfspl 48 4 0 2 1 0 1 1 0 8 0 sessionpl 144 19 0 9 1 0 1 1 0 8 0 pgrppl 48 19 0 9 1 0 1 1 0 8 0 ucredpl 104 71 0 59 1 0 1 1 0 8 0 zombiepl 144 325 0 325 1 0 1 1 0 8 1 processpl 1072 359 0 325 4 0 4 4 0 8 1 procpl 680 370 0 325 6 1 5 5 0 8 1 sockpl 488 91 0 67 4 0 4 4 0 8 0 mcl8k 8192 5 0 0 1 0 1 1 0 8 0 mcl4k 4096 1 0 0 1 0 1 1 0 8 0 mcl2k 2048 268 0 0 34 0 34 34 0 8 0 mtagpl 96 2 0 0 1 0 1 1 0 8 0 mbufpl 256 287 0 0 18 0 18 18 0 8 0 bufpl 288 4108 0 137 284 0 284 284 0 8 0 anonpl 24 198081 0 194246 54 0 54 54 0 186 29 amapchunkpl 152 10191 0 9769 27 0 27 27 0 158 9 amappl16 200 5696 0 5636 5 0 5 5 0 8 1 amappl15 192 11 0 11 1 1 0 1 0 8 0 amappl14 184 141 0 129 2 0 2 2 0 8 1 amappl13 176 14 0 13 2 1 1 1 0 8 0 amappl12 168 935 0 915 3 1 2 2 0 8 1 amappl11 160 64 0 48 1 0 1 1 0 8 0 amappl10 152 54 0 50 1 0 1 1 0 8 0 amappl9 144 197 0 197 1 0 1 1 0 8 1 amappl8 136 103 0 84 2 0 2 2 0 8 1 amappl7 128 58 0 52 2 0 2 2 0 8 0 amappl6 120 183 0 165 2 0 2 2 0 8 1 amappl5 112 136 0 124 1 0 1 1 0 8 0 amappl4 104 547 0 507 2 0 2 2 0 8 0 amappl3 96 2420 0 2374 2 0 2 2 0 8 0 amappl2 88 602 0 545 3 0 3 3 0 8 1 amappl1 80 10214 0 9718 24 1 23 23 0 8 11 amappl 88 2478 0 2372 4 0 4 4 0 92 1 dma4096 4096 1 0 1 1 1 0 1 0 8 0 dma1024 1024 1 0 0 1 0 1 1 0 8 0 dma256 256 6 0 6 1 1 0 1 0 8 0 dma128 128 253 0 253 1 1 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 2 0 0 1 0 1 1 0 8 0 uaddrrnd 24 343 0 326 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 343 0 326 1 0 1 1 0 8 0 vmmpekpl 168 9522 0 9498 2 0 2 2 0 8 0 vmmpepl 168 42366 0 41042 118 3 115 115 0 357 57 vmsppl 464 342 0 326 4 0 4 4 0 8 1 rwobjpl 56 20960 0 18599 46 0 46 46 0 8 10 pdppl 4096 694 0 652 82 24 58 66 0 8 16 pvpl 32 391122 0 382731 337 1 336 337 0 265 264 pmappl 248 342 0 326 2 0 2 2 0 8 0 extentpl 40 56 0 38 1 0 1 1 0 8 0 phpool 112 630 0 27 18 0 18 18 0 8 0 ddb{1}> machine ddbcpu 0 Stopped at x86_ipi_db+0x1e: addq $0x8,%rsp ddb{0}> trace x86_ipi_db(ffffffff82b9dff0) at x86_ipi_db+0x1e sys/arch/amd64/amd64/db_interface.c:393 x86_ipi_handler() at x86_ipi_handler+0xb7 sys/arch/amd64/amd64/ipi.c:106 Xresume_lapic_ipi() at Xresume_lapic_ipi+0x27 __mp_lock(ffffffff82c75a50) at __mp_lock+0x122 __mp_lock_spin sys/kern/kern_lock.c:116 [inline] __mp_lock(ffffffff82c75a50) at __mp_lock+0x122 sys/kern/kern_lock.c:147 yield() at yield+0x37 sys/kern/sched_bsd.c:321 uvm_pagezero_thread(ffff8000211b22b0) at uvm_pagezero_thread+0x6d sys/uvm/uvm_pmemrange.c:2170 end trace frame: 0x0, count: -6 ddb{0}> machine ddbcpu 1 Stopped at db_enter+0x1c: addq $0x8,%rsp ddb{1}> trace db_enter() at db_enter+0x1c sys/arch/amd64/amd64/db_interface.c:437 witness_checkorder(ffff800021210980,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2510 [inline] witness_checkorder(ffff800021210980,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1110 mtx_enter(ffff800021210970) at mtx_enter+0x3e sys/kern/kern_lock.c:265 single_thread_set(ffff800021225010,0,1) at single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] single_thread_set(ffff800021225010,0,1) at single_thread_set+0x35a sys/kern/kern_sig.c:2155 sigexit(ffff800021225010,6) at sigexit+0x90 sys/kern/kern_sig.c:1562 postsig(ffff800021225010,6,ffff800021297048) at postsig+0x4a9 sys/kern/kern_sig.c:1494 userret(ffff800021225010) at userret+0x16e sys/kern/kern_sig.c:1987 syscall(ffff800021297180) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff800021297180) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0x5bd165ae3f0, count: -9 ddb{1}>