syzbot


uvm_fault: remrunqueue

Status: upstream: reported on 2026/05/12 06:18
Reported-by: syzbot+a6db90562083d1335c82@syzkaller.appspotmail.com
First crash: 8d21h, last: 8d21h

Sample crash report:
uvm_fault(0xfffffd806c6df7b8, 0x98, 0, 1) -> e
kernel: page fault trap, codeuvm_fault(0xffffffff83a3b708, 0xffffffffffffffff, 0, 2) -> e
kernel: page fault trap, code=2
Stopped at      remrunqueue+0x116:      movq    %rcx,0(%r12)
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  47055  95820      0           0          0    1  syz-executor
* 67015  95820      0           0  0x4000000    0  syz-executor
remrunqueue(ffff80003a3cd778) at remrunqueue+0x116 sys/kern/kern_sched.c:313
schedcpu(0) at schedcpu+0x306 sys/kern/sched_bsd.c:280
timeout_run(ffffffff8394c478,ffffffff838c4230) at timeout_run+0x159 sys/kern/kern_timeout.c:698
softclock_process_tick_timeout(ffffffff838c4230,0) at softclock_process_tick_timeout+0x232 sys/kern/kern_timeout.c:756
softclock(0) at softclock+0x152 sys/kern/kern_timeout.c:788
softintr_dispatch(0) at softintr_dispatch+0x13b sys/kern/kern_softintr.c:84
dosoftint(0) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
cnputc(65) at cnputc+0x67 sys/dev/cons.c:218
db_putchar(65) at db_putchar+0x36d sys/ddb/db_output.c:155
kprintf() at kprintf+0x223 sys/kern/subr_prf.c:723
db_printf(ffffffff834159ef) at db_printf+0x9b sys/kern/subr_prf.c:-1
db_ktrap(6,0,ffff80003c3d9060) at db_ktrap+0x1c7 sys/arch/amd64/amd64/db_interface.c:129
kerntrap(ffff80003c3d9060) at kerntrap+0x243 sys/arch/amd64/amd64/trap.c:519
end trace frame: 0xffff80003c3d90e0, count: 0
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{0}> 
ddb{0}> set $lines = 0
ddb{0}> set $maxwidth = 0
ddb{0}> show panic
*cpu0: uvm_fault(0xffffffff83a3b708, 0xffffffffffffffff, 0, 2) -> e
ddb{0}> trace
remrunqueue(ffff80003a3cd778) at remrunqueue+0x116 sys/kern/kern_sched.c:313
schedcpu(0) at schedcpu+0x306 sys/kern/sched_bsd.c:280
timeout_run(ffffffff8394c478,ffffffff838c4230) at timeout_run+0x159 sys/kern/kern_timeout.c:698
softclock_process_tick_timeout(ffffffff838c4230,0) at softclock_process_tick_timeout+0x232 sys/kern/kern_timeout.c:756
softclock(0) at softclock+0x152 sys/kern/kern_timeout.c:788
softintr_dispatch(0) at softintr_dispatch+0x13b sys/kern/kern_softintr.c:84
dosoftint(0) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
cnputc(65) at cnputc+0x67 sys/dev/cons.c:218
db_putchar(65) at db_putchar+0x36d sys/ddb/db_output.c:155
kprintf() at kprintf+0x223 sys/kern/subr_prf.c:723
db_printf(ffffffff834159ef) at db_printf+0x9b sys/kern/subr_prf.c:-1
db_ktrap(6,0,ffff80003c3d9060) at db_ktrap+0x1c7 sys/arch/amd64/amd64/db_interface.c:129
kerntrap(ffff80003c3d9060) at kerntrap+0x243 sys/arch/amd64/amd64/trap.c:519
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
dovutimens(ffff80003a3cdca8,fffffd806c4261b8,ffff80003c3d9240) at dovutimens+0x368 sys/kern/vfs_syscalls.c:2771
sys_futimes(ffff80003a3cdca8,ffff80003c3d9390,ffff80003c3d92e0) at sys_futimes+0x208 sys/kern/vfs_syscalls.c:2813
syscall(ffff80003c3d9390) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c3d9390) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x79243f55310, count: -19
ddb{0}> show registers
rdi                                0
rsi                                0
rbp               0xffff80003c3d8b00
rbx                                0
rdx               0xffff8000015c7d80
rcx                                0
rax                              0xc
r8                0xffff80003c3d8f60
r9                0x8080808080808080
r10               0x8cded1974f249ab3
r11               0x9e2d4336f8aec137
r12               0xffffffffffffffff
r13               0xffff8000299adff0
r14               0xffff80003a3cd778
r15                              0xc
rip               0xffffffff815e2176    remrunqueue+0x116
cs                               0x8
rflags                       0x10206    __ALIGN_SIZE+0xf206
rsp               0xffff80003c3d8ac0
ss                              0x10
remrunqueue+0x116:      movq    %rcx,0(%r12)
ddb{0}> show proc
PROC (syz-executor) tid=67015 pid=95820 tcnt=2 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=32, usrpri=55, slppri=32, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80003a3cd778,0xffff80003a3cc7f8
    process=0xffff80002a393038 user=0xffff80003c3d4000, vmspace=0xfffffd806c6df7b8
    estcpu=5, cpticks=1, pctcpu=0.0, user=0, sys=0, intr=1
ddb{0}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 52406  155027  75761      0  2           0                syz-executor
 95820   47055  54446      0  7           0                syz-executor
*95820   67015  54446      0  7   0x4000000                syz-executor
 98261  143060  65781      0  2    0x100000                sh
 65781   29312  12635      0  3    0x10008a  sigsusp       sh
 88119  159784  12067      0  2    0x100002                sh
 38077  345318  20530      0  2           0                syz-executor
  5285  249720   8727      0  2   0x1000000                syz-executor
  5285  187300   8727      0  3   0x5000080  fsleep        syz-executor
 51068  513319  34766      0  2           0                syz-executor
 51068   57093  34766      0  3   0x4000080  fsleep        syz-executor
 51068  419429  34766      0  3   0x4000080  fsleep        syz-executor
 41374  518575  44177      0  2           0                syz-executor
 41374  293026  44177      0  3   0x4000080  fsleep        syz-executor
 34766  131391  34527      0  3        0x82  nanoslp       syz-executor
 44177   96824  34527      0  3        0x82  nanoslp       syz-executor
 20530  317780  34527      0  3        0x82  nanoslp       syz-executor
  8727  194338  34527      0  3        0x82  nanoslp       syz-executor
 54446  295306  34527      0  3        0x82  nanoslp       syz-executor
 75761  323242  34527      0  3        0x82  nanoslp       syz-executor
 12067  450419  34527      0  3        0x82  wait          syz-executor
 12635  216212  34527      0  3        0x82  wait          syz-executor
 34527  446976  34398      0  3        0x82  kqread        syz-executor
 34398  408857  89932      0  3    0x10008a  sigsusp       ksh
 89932  498334  18563      0  3        0x98  kqread        sshd-session
 18563  305144  64700      0  3        0x92  kqread        sshd-session
 95069  276641      1      0  3    0x100083  ttyin         getty
 64700   16788      1      0  3        0x88  kqread        sshd
  8124  165205  62566     74  3   0x1100092  bpf           pflogd
 62566  220351      1      0  3        0x80  sbwait        pflogd
  1521  478330  72901     73  3   0x1100090  kqread        syslogd
 72901  261184      1      0  3    0x100082  sbwait        syslogd
 76733  168807      1      0  3    0x100080  kqread        resolvd
 14456  292978  65215     77  3    0x100092  kqread        dhcpleased
 38621  255434  65215     77  3    0x100092  kqread        dhcpleased
 65215  432284      1      0  3        0x80  kqread        dhcpleased
 38629   80075      0      0  3     0x14200  pause         smr
 32083  316717      0      0  2     0x14200                zerothread
 82999  478769      0      0  3     0x14200  aiodoned      aiodoned
 70954  386916      0      0  3     0x14200  syncer        update
 52110  114465      0      0  3     0x14200  cleaner       cleaner
 68982  240431      0      0  3     0x14200  reaper        reaper
 12246  144490      0      0  3     0x14200  pgdaemon      pagedaemon
 13655  218442      0      0  3     0x14200  bored         viomb
  9012  452451      0      0  3  0x40014200  acpi0         acpi0
 90933  138463      0      0  3  0x40014200                idle1
 43298  228738      0      0  3     0x14200  bored         softnet1
 76897   68974      0      0  3     0x14200  bored         softnet0
  2512  220083      0      0  3     0x14200  smrbar        systqmp
 44743  437366      0      0  3     0x14200  bored         systq
 83984  409690      0      0  3     0x14200  tmoslp        softclockmp
 49399  331795      0      0  3  0x40014200  tmoslp        softclock
 55364  367460      0      0  3  0x40014200                idle0
     1  139305      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{0}> show all locks
Process 95820 (syz-executor) thread 0xffff80003a3cdca8 (67015)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff839cb0c0)
#0  witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1  syscall+0xaf4 mi_syscall sys/sys/syscall_mi.h:175 [inline]
#1  syscall+0xaf4 sys/arch/amd64/amd64/trap.c:783
#2  Xsyscall+0x128
Process 2512 (systqmp) thread 0xffff8000ffffe000 (220083)
shared rwlock systqmp r = 0 (0xffffffff838e67e8)
#0  witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1  taskq_thread+0x12a sys/kern/kern_task.c:442
#2  proc_trampoline+0x10
ddb{0}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11059  12149K   12295K 166960K     12167        0
            pcb    17     12K      12K 166960K        21        0
         rtable   207      5K       6K 166960K       315        0
             pf    34     17K      18K 166960K        45        0
         ifaddr    39      6K       6K 166960K        41        0
        ifgroup    55      2K       2K 166960K        55        0
         sysctl     1      1K       9K 166960K         5        0
       counters    70     37K      37K 166960K        70        0
       ioctlops     0      0K       4K 166960K      1485        0
            iov     0      0K       2K 166960K         1        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1290     81K      81K 166960K      1368        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       1K 166960K         2        0
         VM map     2      1K       1K 166960K         2        0
            sem     2      0K       0K 166960K         2        0
        dirhash    12      2K       2K 166960K        12        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    19     69K      89K 166960K       137        0
           proc    70    115K     164K 166960K       538        0
        subproc    72      4K       4K 166960K        72        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K         2        0
       in_multi    79      5K       5K 166960K        79        0
    ether_multi     1      0K       0K 166960K         1        0
            mrt     0      0K       0K 166960K         2        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys    43    201K     201K 166960K        43        0
           exec     0      0K       1K 166960K       370        0
   fusefs mount     1     32K      32K 166960K         1        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   217    161K     167K 166960K      3111        0
       UVM aobj     3      2K       2K 166960K         3        0
     pinsyscall    44     88K     100K 166960K      1255        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
            NDP    24      1K       1K 166960K        24        0
           temp    36   9074K    9138K 166960K      4007        0
         kqueue    14     22K      24K 166960K        25        0
      SYN cache     2     16K      16K 166960K         2        0
ddb{0}> 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       30    0       27     1     0     1     1     0     8    0
rtentry    176       99    0        4     5     0     5     5     0     8    0
unpcb      144       39    0       20     1     0     1     1     0     8    0
syncache   336        3    0        3     1     0     1     1     0     8    1
tcpcb      736       13    0        9     1     0     1     1     0     8    0
arp        136       18    0        1     1     0     1     1     0     8    0
inpcb      328       72    0       65     2     0     2     2     0     8    1
nd6        152       18    0        0     1     0     1     1     0     8    0
kcovpl      48        8    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       16    0        0     1     0     1     1     0     8    0
pfstkey    128       16    0        0     1     0     1     1     0     8    0
pfstate    448       16    0        0     2     0     2     2     0     8    0
pfrule     1360      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      378    0        2    24     0    24    24     0     8    0
art_table   40      379    0        2     4     0     4     4     0     8    0
art_node    32       99    0       11     1     0     1     1     0     8    0
sysvmsgpl   40        1    0        1     1     0     1     1     0     8    1
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     1576    0      111    92     0    92    92     0     8    0
ffsino     296     1576    0      111   114     0   114   114     0     8    1
nchpl      144     1783    0       85    63     0    63    63     0     8    0
vnodes     216     1668    0        0    93     0    93    93     0     8    0
namei      1024    5349    0     5349     1     0     1     1     0     8    1
percpumem   16       50    0        0     1     0     1     1     0     8    0
kstatmem   264       27    0        0     2     0     2     2     0     8    0
scxspl     216     6231    0     6231     4     1     3     3     1     8    3
plimitpl   152       27    0       10     1     0     1     1     0     8    0
sigapl     424      449    0      400     7     0     7     7     0     8    1
knotepl    120       56    0        0     2     0     2     2     0     8    0
kqueuepl   224       22    0       12     1     0     1     1     0     8    0
pipepl     344      122    0       95     3     0     3     3     0     8    0
fdescpl    528      433    0      400     3     0     3     3     0     8    0
filepl     160     1552    0     1339    10     0    10    10     0     8    0
lockfpl    104       11    0        8     1     0     1     1     0     8    0
lockfspl    48        7    0        4     1     0     1     1     0     8    0
sessionpl  144       22    0       13     1     0     1     1     0     8    0
pgrppl      48       30    0       13     1     0     1     1     0     8    0
ucredpl    104       90    0       77     1     0     1     1     0     8    0
zombiepl   144      400    0      400     1     0     1     1     0     8    1
processpl  1232     449    0      400     5     0     5     5     0     8    1
procpl     664      464    0      410     5     0     5     5     0     8    0
sockpl     752      141    0      112     4     0     4     4     0     8    0
mcl8k      8192       3    0        0     1     0     1     1     0     8    0
mcl4k      4096     116    0        0    15     0    15    15     0     8    0
mcl2k      2048      14    0        0     2     0     2     2     0     8    0
mtagpl      96        4    0        0     1     0     1     1     0     8    0
mbufpl     256      116    0        0     8     0     8     8     0     8    0
bufpl      280     2342    0      105   160     0   160   160     0     8    0
anonpl      32     7676    0        0    62     0    62    62     0   246    0
amapchunkpl 152    8534    0     8098    19     0    19    19     0   158    1
amappl16   200     2221    0     1964    15     0    15    15     0     8    0
amappl15   192       18    0       18     1     0     1     1     0     8    1
amappl14   184      425    0      421     1     0     1     1     0     8    0
amappl13   176      154    0      142     1     0     1     1     0     8    0
amappl12   168      696    0      666     2     0     2     2     0     8    0
amappl11   160        4    0        3     1     0     1     1     0     8    0
amappl10   152       90    0       76     1     0     1     1     0     8    0
amappl9    144      271    0      270     1     0     1     1     0     8    0
amappl8    136       98    0       96     1     0     1     1     0     8    0
amappl7    128      139    0      126     1     0     1     1     0     8    0
amappl6    120      159    0      156     1     0     1     1     0     8    0
amappl5    112       95    0       85     1     0     1     1     0     8    0
amappl4    104      275    0      258     1     0     1     1     0     8    0
amappl3     96     1433    0     1331     3     0     3     3     0     8    0
amappl2     88      504    0      443     2     0     2     2     0     8    0
amappl1     80     9106    0     8489    14     0    14    14     0     8    0
amappl      88     2416    0     2272     4     0     4     4     0    92    0
uvmvnodes   80      100    0        0     3     0     3     3     0     8    0
dma4096    4096       1    0        1     1     1     0     1     0     8    0
dma2048    2048       1    0        1     1     0     1     1     0     8    1
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      433    0      400     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      433    0      400     1     0     1     1     0     8    0
vmmpekpl   168     5234    0     5203     2     0     2     2     0     8    0
vmmpepl    168    36119    0    33995    96     0    96    96     0   357    2
vmsppl     488      432    0      400     5     0     5     5     0     8    0
rwobjpl     80    13800    0    12539    28     0    28    28     0     8    0
pdppl      4096     873    0      800    95    12    83    83     0     8   10
pvpl        32    14821    0        0   120     0   120   120     0   265    0
pmappl     256      432    0      400     3     0     3     3     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      255    0       15     7     0     7     7     0     8    0
ddb{0}> machine ddbcpu 0
Invalid cpu 0
ddb{0}> trace
remrunqueue(ffff80003a3cd778) at remrunqueue+0x116 sys/kern/kern_sched.c:313
schedcpu(0) at schedcpu+0x306 sys/kern/sched_bsd.c:280
timeout_run(ffffffff8394c478,ffffffff838c4230) at timeout_run+0x159 sys/kern/kern_timeout.c:698
softclock_process_tick_timeout(ffffffff838c4230,0) at softclock_process_tick_timeout+0x232 sys/kern/kern_timeout.c:756
softclock(0) at softclock+0x152 sys/kern/kern_timeout.c:788
softintr_dispatch(0) at softintr_dispatch+0x13b sys/kern/kern_softintr.c:84
dosoftint(0) at dosoftint+0x54 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
cnputc(65) at cnputc+0x67 sys/dev/cons.c:218
db_putchar(65) at db_putchar+0x36d sys/ddb/db_output.c:155
kprintf() at kprintf+0x223 sys/kern/subr_prf.c:723
db_printf(ffffffff834159ef) at db_printf+0x9b sys/kern/subr_prf.c:-1
db_ktrap(6,0,ffff80003c3d9060) at db_ktrap+0x1c7 sys/arch/amd64/amd64/db_interface.c:129
kerntrap(ffff80003c3d9060) at kerntrap+0x243 sys/arch/amd64/amd64/trap.c:519
alltraps_kern_meltdown() at alltraps_kern_meltdown+0x7b
dovutimens(ffff80003a3cdca8,fffffd806c4261b8,ffff80003c3d9240) at dovutimens+0x368 sys/kern/vfs_syscalls.c:2771
sys_futimes(ffff80003a3cdca8,ffff80003c3d9390,ffff80003c3d92e0) at sys_futimes+0x208 sys/kern/vfs_syscalls.c:2813
syscall(ffff80003c3d9390) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c3d9390) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x79243f55310, count: -19
ddb{0}> machine ddbcpu 1

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/12 06:17 openbsd 369ac04692fe 340bcdf0 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore uvm_fault: remrunqueue
* Struck through repros no longer work on HEAD.