witness: lock order reversal: 1st 0xffffffff82cc8bd0 &sched_lock (&sched_lock) 2nd 0xffff8000ffff8118 &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(ffff8000ffff8118,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2510 [inline] witness_checkorder(ffff8000ffff8118,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1110 mtx_enter(ffff8000ffff8108) at mtx_enter+0x3e sys/kern/kern_lock.c:265 single_thread_set(ffff80002120daa8,0,1) at single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] single_thread_set(ffff80002120daa8,0,1) at single_thread_set+0x35a sys/kern/kern_sig.c:2155 sigexit(ffff80002120daa8,6) at sigexit+0x90 sys/kern/kern_sig.c:1562 postsig(ffff80002120daa8,6,ffff8000212a5478) at postsig+0x4a9 sys/kern/kern_sig.c:1494 userret(ffff80002120daa8) at userret+0x16e sys/kern/kern_sig.c:1987 syscall(ffff8000212a55b0) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff8000212a55b0) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xf273bd266c0, count: -9 ddb{1}> show registers rdi 0x3 rsi 0xffffffff82bf22f0 __sancov_gen_cov_switch_values.134 rbp 0xffff8000212a5180 rbx 0x3 rdx 0x3fd rcx 0 rax 0x1 r8 0xffff8000212a50f0 r9 0x8080808080808080 r10 0xfbf1a6f88b6df23 r11 0x7a0a032abfb192 r12 0xfffffd8003a0a220 r13 0 r14 0xfffffd8003a03790 r15 0xfffffd80031c7bc0 rip 0xffffffff81b6e27c db_enter+0x1c cs 0x8 rflags 0x246 rsp 0xffff8000212a5170 ss 0x10 db_enter+0x1c: addq $0x8,%rsp ddb{1}> show proc PROC (syz-executor.0) pid=219125 stat=onproc flags process=100000 proc=4002000 pri=32, usrpri=50, nice=20 forw=0xffffffffffffffff, list=0xffff80002120c018,0xffffffff82c90e98 process=0xffff8000ffff8008 user=0xffff8000212a0000, vmspace=0xfffffd8008a121d0 estcpu=0, cpticks=0, pctcpu=0.0 user=0, sys=0, intr=0 ddb{1}> ps PID TID PPID UID S FLAGS WAIT COMMAND 45808 316616 33692 0 4 0x182000 syz-executor.0 *45808 219125 33692 0 7 0x4102000 syz-executor.0 33692 271844 14738 0 3 0x82 nanoslp syz-executor.0 14738 463076 50357 0 3 0x2000082 thrsleep syz-execprog 14738 229544 50357 0 3 0x6000082 nanoslp syz-execprog 14738 449288 50357 0 3 0x6000082 wait syz-execprog 14738 37325 50357 0 3 0x6000082 thrsleep syz-execprog 14738 86814 50357 0 3 0x6000082 kqread syz-execprog 14738 353502 50357 0 3 0x6000082 thrsleep syz-execprog 14738 188132 50357 0 3 0x6000082 thrsleep syz-execprog 14738 303177 50357 0 3 0x6000082 thrsleep syz-execprog 14738 321800 50357 0 3 0x6000082 thrsleep syz-execprog 14738 139584 50357 0 3 0x6000082 thrsleep syz-execprog 14738 398488 50357 0 3 0x6000082 thrsleep syz-execprog 50357 91928 36406 0 3 0x10008a sigsusp ksh 36406 456201 38239 0 3 0x9a kqread sshd 90074 128733 1 0 3 0x100083 ttyin getty 38239 105532 1 0 3 0x88 kqread sshd 99134 165507 80058 73 3 0x1100090 kqread syslogd 80058 279605 1 0 3 0x100082 netio syslogd 39988 47267 1 0 3 0x100080 kqread resolvd 97371 101395 2882 77 3 0x100092 kqread dhcpleased 62659 476370 2882 77 3 0x100092 kqread dhcpleased 2882 32042 1 0 3 0x80 kqread dhcpleased 53730 136189 0 0 3 0x14200 bored smr 62951 175729 0 0 7 0x14200 zerothread 20443 180118 0 0 3 0x14200 aiodoned aiodoned 24455 412302 0 0 3 0x14200 syncer update 71094 408911 0 0 3 0x14200 cleaner cleaner 53507 450485 0 0 3 0x14200 reaper reaper 24724 274717 0 0 3 0x14200 pgdaemon pagedaemon 38409 309299 0 0 3 0x14200 bored viomb 26005 377362 0 0 3 0x40014200 acpi0 acpi0 28039 467950 0 0 3 0x40014200 idle1 15928 132289 0 0 3 0x14200 bored softnet3 51026 158582 0 0 3 0x14200 bored softnet2 40256 185925 0 0 3 0x14200 bored softnet1 94704 160923 0 0 3 0x14200 bored softnet0 64639 358841 0 0 3 0x14200 bored systqmp 23452 272172 0 0 3 0x14200 bored systq 3368 430839 0 0 3 0x40014200 bored softclock 98339 470988 0 0 3 0x40014200 idle0 1 17666 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 (0xffffffff82cc8bd0) #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 45808 (syz-executor.0) thread 0xffff80002120daa8 (219125) exclusive kernel_lock &kernel_lock r = 0 (0xffffffff82ca0228) #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 (0xffffffff82cc8bd0) #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 10159 6391K 6420K 78643K 11237 0 pcb 13 8K 8K 78643K 13 0 rtable 80 2K 2K 78643K 140 0 pf 15 6K 6K 78643K 15 0 ifaddr 16 10K 10K 78643K 16 0 ifgroup 22 1K 1K 78643K 22 0 counters 46 34K 34K 78643K 46 0 ioctlops 0 0K 2K 78643K 22 0 mount 1 1K 1K 78643K 1 0 log 0 0K 0K 78643K 4 0 vnodes 1174 73K 74K 78643K 1187 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 24 0 proc 55 78K 91K 78643K 274 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 274 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 162 16K 16K 78643K 2739 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 6 0K 0K 78643K 6 0 temp 1 5904K 5968K 78643K 3196 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 22 0 19 1 0 1 1 0 8 0 rtentry 112 34 0 1 1 0 1 1 0 8 0 unpcb 144 33 0 20 1 0 1 1 0 8 0 syncache 304 5 0 5 1 0 1 1 0 8 1 tcpqe 32 225 0 225 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 30 0 24 1 0 1 1 0 8 0 nd6 136 3 0 0 1 0 1 1 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 1455 0 51 88 0 88 88 0 8 0 ffsino 272 1455 0 51 94 0 94 94 0 8 0 nchpl 144 1692 0 61 61 0 61 61 0 8 0 uvmvnodes 80 1464 0 0 30 0 30 30 0 8 0 vnodes 216 1464 0 0 82 0 82 82 0 8 0 namei 1024 5190 0 5190 2 0 2 2 0 8 2 percpumem 16 36 0 0 1 0 1 1 0 8 0 kstatmem 264 8 0 0 1 0 1 1 0 8 0 scxspl 216 6397 0 6397 10 2 8 8 1 8 8 plimitpl 152 27 0 19 1 0 1 1 0 8 0 sigapl 424 341 0 309 5 0 5 5 0 8 1 knotepl 120 70 0 0 3 0 3 3 0 8 0 kqueuepl 216 21 0 13 1 0 1 1 0 8 0 pipepl 320 111 0 104 2 0 2 2 0 8 1 fdescpl 496 324 0 309 5 1 4 4 0 8 2 filepl 152 1389 0 1324 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 18 0 9 1 0 1 1 0 8 0 pgrppl 48 18 0 9 1 0 1 1 0 8 0 ucredpl 104 66 0 56 1 0 1 1 0 8 0 zombiepl 144 309 0 309 1 0 1 1 0 8 1 processpl 1072 341 0 309 3 0 3 3 0 8 0 procpl 680 352 0 309 5 0 5 5 0 8 1 sockpl 488 85 0 63 3 0 3 3 0 8 0 mcl8k 8192 5 0 0 1 0 1 1 0 8 0 mcl4k 4096 3 0 0 1 0 1 1 0 8 0 mcl2k 2048 299 0 0 38 0 38 38 0 8 0 mtagpl 96 4 0 0 1 0 1 1 0 8 0 mbufpl 256 311 0 0 20 0 20 20 0 8 0 bufpl 288 4044 0 134 280 0 280 280 0 8 0 anonpl 24 173348 0 169748 58 5 53 53 0 186 27 amapchunkpl 152 9387 0 8993 27 1 26 26 0 158 10 amappl16 200 4691 0 4629 10 5 5 5 0 8 0 amappl15 192 14 0 14 1 1 0 1 0 8 0 amappl14 184 132 0 121 2 0 2 2 0 8 1 amappl13 176 78 0 78 1 1 0 1 0 8 0 amappl12 168 870 0 851 2 0 2 2 0 8 1 amappl11 160 49 0 38 1 0 1 1 0 8 0 amappl10 152 40 0 39 2 1 1 1 0 8 0 amappl9 144 213 0 213 2 1 1 1 0 8 1 amappl8 136 129 0 108 2 0 2 2 0 8 1 amappl7 128 64 0 58 2 0 2 2 0 8 0 amappl6 120 189 0 174 1 0 1 1 0 8 0 amappl5 112 137 0 126 1 0 1 1 0 8 0 amappl4 104 511 0 476 2 0 2 2 0 8 0 amappl3 96 2366 0 2325 2 0 2 2 0 8 1 amappl2 88 581 0 531 4 1 3 3 0 8 1 amappl1 80 10030 0 9572 22 0 22 22 0 8 11 amappl 88 2315 0 2215 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 24 325 0 310 1 0 1 1 0 8 0 uaddrbest 32 2 0 0 1 0 1 1 0 8 0 uaddr 24 325 0 310 1 0 1 1 0 8 0 vmmpekpl 168 9175 0 9152 2 0 2 2 0 8 0 vmmpepl 168 40336 0 39129 113 2 111 111 0 357 58 vmsppl 464 324 0 310 5 1 4 4 0 8 2 rwobjpl 56 19590 0 17313 46 1 45 45 0 8 8 pdppl 4096 658 0 620 82 28 54 62 0 8 16 pvpl 32 360846 0 353058 343 7 336 337 0 265 265 pmappl 248 324 0 310 3 1 2 2 0 8 1 extentpl 40 56 0 38 1 0 1 1 0 8 0 phpool 112 629 0 30 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(ffffffff82c05ff0) 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 __sanitizer_cov_trace_pc() at __sanitizer_cov_trace_pc+0xf sys/dev/kcov.c:154 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(ffff8000ffff8118,9,0) at witness_checkorder+0x10b7 witness_debugger sys/kern/subr_witness.c:2510 [inline] witness_checkorder(ffff8000ffff8118,9,0) at witness_checkorder+0x10b7 sys/kern/subr_witness.c:1110 mtx_enter(ffff8000ffff8108) at mtx_enter+0x3e sys/kern/kern_lock.c:265 single_thread_set(ffff80002120daa8,0,1) at single_thread_set+0x35a single_thread_wait sys/kern/kern_sig.c:2172 [inline] single_thread_set(ffff80002120daa8,0,1) at single_thread_set+0x35a sys/kern/kern_sig.c:2155 sigexit(ffff80002120daa8,6) at sigexit+0x90 sys/kern/kern_sig.c:1562 postsig(ffff80002120daa8,6,ffff8000212a5478) at postsig+0x4a9 sys/kern/kern_sig.c:1494 userret(ffff80002120daa8) at userret+0x16e sys/kern/kern_sig.c:1987 syscall(ffff8000212a55b0) at syscall+0x4e7 mi_syscall_return sys/sys/syscall_mi.h:137 [inline] syscall(ffff8000212a55b0) at syscall+0x4e7 sys/arch/amd64/amd64/trap.c:644 Xsyscall() at Xsyscall+0x128 end of kernel end trace frame: 0xf273bd266c0, count: -9 ddb{1}>