syzbot


panic: ffs2_balloc: unwind failed (4)

Status: upstream: reported on 2026/04/03 13:33
Reported-by: syzbot+6a85d4fe8fa209ea90f7@syzkaller.appspotmail.com
First crash: 8d00h, last: 17h50m
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd panic: ffs2_balloc: unwind failed (2) 2 1 404d 404d 0/3 auto-obsoleted due to no activity on 2025/06/01 04:48
openbsd panic: ffs2_balloc: unwind failed (3) 2 1 189d 189d 0/3 auto-obsoleted due to no activity on 2026/01/01 15:18
openbsd panic: ffs2_balloc: unwind failed 2 1 573d 573d 0/3 auto-obsoleted due to no activity on 2024/12/13 17:12

Sample crash report:
panic: ffs2_balloc: unwind failed
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
  60333  72267      0           0          0    0  syz-executor
*440451  72267      0           0  0x4000000    1K syz-executor
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff833d72da) at panic+0x1e5 sys/kern/subr_prf.c:198
ffs2_balloc(fffffd806a0f8270,40000000006,1,fffffd80097fd270,1,ffff80003c47b360) at ffs2_balloc+0x1961
ffs_truncate(fffffd806a0f8270,40000000007,0,fffffd80097fd270) at ffs_truncate+0x410 sys/ufs/ffs/ffs_inode.c:185
ufs_setattr(ffff80003c47b480) at ufs_setattr+0x8e9 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffffd8066c8ab00,ffff80003c47b508,fffffd80097fd270,ffff80003c4682c8) at VOP_SETATTR+0x11b sys/kern/vfs_vops.c:210
dotruncate(ffff80003c4682c8,fffffd8066c8ab00,40000000007) at dotruncate+0x1da sys/kern/vfs_syscalls.c:2892
sys_ftruncate(ffff80003c4682c8,ffff80003c47b730,ffff80003c47b680) at sys_ftruncate+0x20a sys/kern/vfs_syscalls.c:2946
syscall(ffff80003c47b730) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c47b730) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9dff4dddcd0, count: 5
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}> 
ddb{1}> set $lines = 0
ddb{1}> set $maxwidth = 0
ddb{1}> show panic
*cpu1: ffs2_balloc: unwind failed
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff833d72da) at panic+0x1e5 sys/kern/subr_prf.c:198
ffs2_balloc(fffffd806a0f8270,40000000006,1,fffffd80097fd270,1,ffff80003c47b360) at ffs2_balloc+0x1961
ffs_truncate(fffffd806a0f8270,40000000007,0,fffffd80097fd270) at ffs_truncate+0x410 sys/ufs/ffs/ffs_inode.c:185
ufs_setattr(ffff80003c47b480) at ufs_setattr+0x8e9 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffffd8066c8ab00,ffff80003c47b508,fffffd80097fd270,ffff80003c4682c8) at VOP_SETATTR+0x11b sys/kern/vfs_vops.c:210
dotruncate(ffff80003c4682c8,fffffd8066c8ab00,40000000007) at dotruncate+0x1da sys/kern/vfs_syscalls.c:2892
sys_ftruncate(ffff80003c4682c8,ffff80003c47b730,ffff80003c47b680) at sys_ftruncate+0x20a sys/kern/vfs_syscalls.c:2946
syscall(ffff80003c47b730) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c47b730) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9dff4dddcd0, count: -10
ddb{1}> show registers
rdi                                0
rsi                              0x1
rbp               0xffff80003c47afc0
rbx               0xffff8000299bee07
rdx                                0
rcx               0xffff80003c4682c8
rax               0xffff8000299bdff0
r8                 0x101010101010101
r9                0x8080808080808080
r10               0x5e55a24b0599fbc0
r11               0x9fd5ee69eabbc3af
r12               0xffff8000299bec08
r13                                0
r14                                0
r15                              0x1
rip               0xffffffff810ba845    db_enter+0x25
cs                               0x8
rflags                         0x246
rsp               0xffff80003c47afb0
ss                                 0
db_enter+0x25:  addq    $0x8,%rsp
ddb{1}> show proc
PROC (syz-executor) tid=440451 pid=72267 tcnt=4 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=17, usrpri=63, slppri=17, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff80003c4687f8,0xffff80003c469798
    process=0xffff8000fffee1c8 user=0xffff80003c476000, vmspace=0xfffffd80687a37c0
    estcpu=36, cpticks=1, pctcpu=0.0, user=0, sys=1, intr=0
ddb{1}> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
  1050  401149  74724      0  2           0                syz-executor
  1050  179478  74724      0  3   0x4000080  fsleep        syz-executor
 72267   60333  43764      0  7           0                syz-executor
 72267   24333  43764      0  3   0x4000080  fsleep        syz-executor
*72267  440451  43764      0  7   0x4000000                syz-executor
 72267  136165  43764      0  3   0x4000080  fsleep        syz-executor
 26616  105157  16277      0  2           0                syz-executor
 26616  258824  16277      0  3   0x4000080  kqsel         syz-executor
 80802  324230  47575      0  3        0x80  nanoslp       syz-executor
 80802  334246  47575      0  3   0x4000080  fsleep        syz-executor
 80802  231849  47575      0  3   0x4000080  fsleep        syz-executor
 80802  207444  47575      0  3   0x4000080  fsleep        syz-executor
 42740  384353  26074      0  2           0                syz-executor
 49197  426350  51282      0  2         0x2                sh
 33953  147141  57365      0  2           0                syz-executor
 89300  241173  27325      0  2           0                syz-executor
 89300  458121  27325      0  3   0x4000080  fsleep        syz-executor
 60811   63824      0      0  3     0x14280  nfsidl        nfsio
 28472  484496      0      0  3     0x14280  nfsidl        nfsio
 20263  355077      0      0  3     0x14280  nfsidl        nfsio
 62815  162430      0      0  3     0x14280  nfsidl        nfsio
 23579  260301      0      0  3     0x14280  nfsidl        nfsio
 62027  133465      0      0  3     0x14280  nfsidl        nfsio
 32622  147120      0      0  3     0x14280  nfsidl        nfsio
 89684  272760      0      0  3     0x14280  nfsidl        nfsio
 90293  113495      0      0  3     0x14280  nfsidl        nfsio
 65569  180703      0      0  3     0x14280  nfsidl        nfsio
  3942   16759      0      0  3     0x14280  nfsidl        nfsio
 43740  349345      0      0  3     0x14280  nfsidl        nfsio
 16302  399288      0      0  3     0x14280  nfsidl        nfsio
 18279  362524      0      0  3     0x14280  nfsidl        nfsio
 94168  215777      0      0  3     0x14280  nfsidl        nfsio
   317   47364      0      0  3     0x14280  nfsidl        nfsio
 10637  166801      0      0  3     0x14280  nfsidl        nfsio
 60467  149879      0      0  3     0x14280  nfsidl        nfsio
 63249  364118      0      0  3     0x14280  nfsidl        nfsio
 96336  304081      0      0  3     0x14280  nfsidl        nfsio
 74724  120985  97965      0  3        0x82  nanoslp       syz-executor
 57365   34358  97965      0  3        0x82  nanoslp       syz-executor
 26074  343111  97965      0  3        0x82  nanoslp       syz-executor
 47575  408806  97965      0  3        0x82  nanoslp       syz-executor
 43764  373106  97965      0  3        0x82  nanoslp       syz-executor
 27325  280275  97965      0  3        0x82  nanoslp       syz-executor
 51282  387085  97965      0  3        0x82  wait          syz-executor
 16277    5066  97965      0  3        0x82  nanoslp       syz-executor
 97965  334440  99761      0  3        0x82  kqread        syz-executor
 99761  245091  72540      0  3    0x10008a  sigsusp       ksh
 72540  398651  21562      0  3        0x98  kqread        sshd-session
 21562  342629  46034      0  3        0x92  kqread        sshd-session
 67833   39042      1      0  3    0x100083  ttyin         getty
 46034  196118      1      0  3        0x88  kqread        sshd
 17749  262358  65678     74  3   0x1100092  bpf           pflogd
 65678   58806      1      0  3        0x80  sbwait        pflogd
 69238  445388  26859     73  3   0x1100090  kqread        syslogd
 26859  262316      1      0  3    0x100082  sbwait        syslogd
 42436  446518      1      0  3    0x100080  kqread        resolvd
 13885   85980  40907     77  3    0x100092  kqread        dhcpleased
 29480  447927  40907     77  3    0x100092  kqread        dhcpleased
 40907  236039      1      0  3        0x80  kqread        dhcpleased
 14688  360924      0      0  3     0x14200  bored         smr
 44809  162581      0      0  2     0x14200                zerothread
 15018  159998      0      0  3     0x14200  aiodoned      aiodoned
 75525  235806      0      0  3     0x14200  syncer        update
 67719  405619      0      0  3     0x14200  cleaner       cleaner
 92178  308244      0      0  3     0x14200  reaper        reaper
 14433   67234      0      0  3     0x14200  pgdaemon      pagedaemon
 12757  439838      0      0  3     0x14200  bored         viomb
 90801  257624      0      0  3  0x40014200  acpi0         acpi0
 68236   31471      0      0  3  0x40014200                idle1
 74941  353129      0      0  3     0x14200  bored         softnet1
 80581  454842      0      0  3     0x14200  bored         softnet0
 16032  402425      0      0  3     0x14200  smrbar        systqmp
 19903  205585      0      0  3     0x14200  bored         systq
 12196  349983      0      0  3     0x14200  tmoslp        softclockmp
  9161  341648      0      0  3  0x40014200  tmoslp        softclock
 78607  370063      0      0  3  0x40014200                idle0
     1  428696      0      0  3        0x82  wait          init
     0       0     -1      0  3     0x10200  scheduler     swapper
ddb{1}> show all locks
Process 72267 (syz-executor) thread 0xffff80003c4682c8 (440451)
exclusive kernel_lock &kernel_lock r = 0 (0xffffffff839dd2c0)
#0  witness_lock+0x5f1 stacktrace_save sys/sys/stacktrace.h:37 [inline]
#0  witness_lock+0x5f1 sys/kern/subr_witness.c:1160
#1  __mp_acquire_count+0x58 sys/kern/kern_lock.c:-1
#2  sleep_finish+0x2d8 sys/kern/kern_synch.c:369
#3  biowait+0xc6 sys/kern/vfs_bio.c:1242
#4  bwrite+0x2e7 sys/kern/vfs_bio.c:754
#5  ffs2_balloc+0xc24 sys/ufs/ffs/ffs_balloc.c:646
#6  ffs_truncate+0x410 sys/ufs/ffs/ffs_inode.c:185
#7  ufs_setattr+0x8e9 sys/ufs/ufs/ufs_vnops.c:403
#8  VOP_SETATTR+0x11b sys/kern/vfs_vops.c:210
#9  dotruncate+0x1da sys/kern/vfs_syscalls.c:2892
#10 sys_ftruncate+0x20a sys/kern/vfs_syscalls.c:2946
#11 syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#11 syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
#12 Xsyscall+0x128
exclusive rrwlock inode r = 0 (0xfffffd806a0f8310)
#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  rrw_enter+0xc6 sys/kern/kern_rwlock.c:621
#3  VOP_LOCK+0xbd sys/kern/vfs_vops.c:527
#4  vn_lock+0xa4 sys/kern/vfs_vnops.c:576
#5  sys_ftruncate+0x1f1 sys/kern/vfs_syscalls.c:2946
#6  syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
#6  syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
#7  Xsyscall+0x128
Process 16032 (systqmp) thread 0xffff8000ffffea60 (402425)
shared rwlock systqmp r = 0 (0xffffffff8389da88)
#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{1}> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11053  12084K   12178K 166960K     12156        0
            pcb    18     12K      12K 166960K        18        0
         rtable   235      6K       6K 166960K       345        0
             pf    34     17K      18K 166960K        45        0
         ifaddr    43      7K       7K 166960K        45        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
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1291     81K      81K 166960K      1370        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    18     65K      93K 166960K       143        0
           proc    70    115K     147K 166960K       552        0
        subproc    72      4K       4K 166960K        72        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
       in_multi    99      7K       7K 166960K        99        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    25    122K     122K 166960K        25        0
           exec     0      0K       1K 166960K       377        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   227    175K     185K 166960K      3046        0
       UVM aobj     3      2K       2K 166960K         3        0
     pinsyscall    43     86K     104K 166960K      1277        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
            NDP    13      0K       2K 166960K        28        0
           temp    34   9070K    9134K 166960K      4051        0
         kqueue    13     20K      20K 166960K        22        0
      SYN cache     2     16K      16K 166960K         2        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       33    0       30     1     0     1     1     0     8    0
rtentry    176      110    0        1     5     0     5     5     0     8    0
unpcb      144       36    0       19     1     0     1     1     0     8    0
syncache   336        3    0        3     1     0     1     1     0     8    1
tcpcb      736       10    0        4     1     0     1     1     0     8    0
arp        136       18    0        0     1     0     1     1     0     8    0
inpcb      328       79    0       67     1     0     1     1     0     8    0
nd6        152       23    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       19    0        0     1     0     1     1     0     8    0
pfstkey    128       19    0        0     1     0     1     1     0     8    0
pfstate    448       19    0        0     3     0     3     3     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      451    0        0    29     0    29    29     0     8    0
art_table   40      452    0        0     5     0     5     5     0     8    0
art_node    32      110    0       10     1     0     1     1     0     8    0
dirhash    1024      17    0        0     3     0     3     3     0     8    0
dino2pl    256     1582    0      115    92     0    92    92     0     8    0
ffsino     296     1582    0      115   113     0   113   113     0     8    0
nchpl      144     1783    0       80    64     0    64    64     0     8    0
vnodes     216     1673    0        0    93     0    93    93     0     8    0
namei      1024    5371    0     5371     1     0     1     1     0     8    1
percpumem   16       50    0        0     1     0     1     1     0     8    0
kstatmem   264       26    0        0     2     0     2     2     0     8    0
scxspl     216     6076    0     6076     4     1     3     3     1     8    3
plimitpl   152       28    0       10     1     0     1     1     0     8    0
sigapl     424      475    0      407     9     0     9     9     0     8    0
knotepl    120       59    0        0     2     0     2     2     0     8    0
kqueuepl   224       19    0        9     1     0     1     1     0     8    0
pipepl     344      122    0       95     3     0     3     3     0     8    0
fdescpl    528      439    0      407     3     0     3     3     0     8    0
filepl     160     1545    0     1329     9     0     9     9     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       69    0       56     1     0     1     1     0     8    0
zombiepl   144      407    0      407     1     0     1     1     0     8    1
processpl  1232     475    0      407     6     0     6     6     0     8    0
procpl     664      494    0      417     7     0     7     7     0     8    0
sockpl     752      149    0      116     4     0     4     4     0     8    0
mcl64k     65536      1    0        0     1     0     1     1     0     8    0
mcl8k      8192       2    0        0     1     0     1     1     0     8    0
mcl4k      4096     121    0        0    16     0    16    16     0     8    0
mcl2k      2048       8    0        0     1     0     1     1     0     8    0
mtagpl      96        1    0        0     1     0     1     1     0     8    0
mbufpl     256      133    0        0     9     0     9     9     0     8    0
bufpl      280     2291    0      105   157     0   157   157     0     8    0
anonpl      32     3859    0        0    32     0    32    32     0   246    0
amapchunkpl 152    8435    0     7973    18     0    18    18     0   158    0
amappl16   200     1789    0     1775     5     1     4     5     0     8    3
amappl15   192       64    0       64     1     1     0     1     0     8    0
amappl14   184      432    0      429     1     0     1     1     0     8    0
amappl13   176      122    0      109     1     0     1     1     0     8    0
amappl12   168      684    0      656     2     0     2     2     0     8    0
amappl11   160        8    0        8     1     1     0     1     0     8    0
amappl10   152       81    0       67     1     0     1     1     0     8    0
amappl9    144      266    0      265     1     0     1     1     0     8    0
amappl8    136      112    0      110     1     0     1     1     0     8    0
amappl7    128      142    0      129     1     0     1     1     0     8    0
amappl6    120      165    0      163     1     0     1     1     0     8    0
amappl5    112       91    0       81     1     0     1     1     0     8    0
amappl4    104      285    0      265     1     0     1     1     0     8    0
amappl3     96     1461    0     1357     3     0     3     3     0     8    0
amappl2     88      509    0      451     2     0     2     2     0     8    0
amappl1     80     9309    0     8699    15     0    15    15     0     8    0
amappl      88     2337    0     2183     4     0     4     4     0    92    0
uvmvnodes   80       99    0        0     3     0     3     3     0     8    0
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      439    0      407     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24      439    0      407     1     0     1     1     0     8    0
vmmpekpl   168     5379    0     5348     2     0     2     2     0     8    0
vmmpepl    168    36341    0    34456    86     0    86    86     0   357    4
vmsppl     488      438    0      407     5     0     5     5     0     8    0
rwobjpl     80    13595    0    12584    24     0    24    24     0     8    1
pdppl      4096     885    0      814    97    18    79    85     0     8    8
pvpl        32     9135    0        0    75     1    74    75     0   265    0
pmappl     256      438    0      407     3     0     3     3     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      264    0       21     8     0     8     8     0     8    0
ddb{1}> machine ddbcpu 0
Stopped at      x86_ipi_db+0x27:        addq    $0x8,%rsp
x86_ipi_db(ffffffff838d7ff0) 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
end of kernel
end trace frame: 0x744b6a0a1020, count: 12
ddb{0}> trace
x86_ipi_db(ffffffff838d7ff0) 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
end of kernel
end trace frame: 0x744b6a0a1020, count: -3
ddb{0}> machine ddbcpu 1
Stopped at      db_enter+0x25:  addq    $0x8,%rsp
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff833d72da) at panic+0x1e5 sys/kern/subr_prf.c:198
ffs2_balloc(fffffd806a0f8270,40000000006,1,fffffd80097fd270,1,ffff80003c47b360) at ffs2_balloc+0x1961
ffs_truncate(fffffd806a0f8270,40000000007,0,fffffd80097fd270) at ffs_truncate+0x410 sys/ufs/ffs/ffs_inode.c:185
ufs_setattr(ffff80003c47b480) at ufs_setattr+0x8e9 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffffd8066c8ab00,ffff80003c47b508,fffffd80097fd270,ffff80003c4682c8) at VOP_SETATTR+0x11b sys/kern/vfs_vops.c:210
dotruncate(ffff80003c4682c8,fffffd8066c8ab00,40000000007) at dotruncate+0x1da sys/kern/vfs_syscalls.c:2892
sys_ftruncate(ffff80003c4682c8,ffff80003c47b730,ffff80003c47b680) at sys_ftruncate+0x20a sys/kern/vfs_syscalls.c:2946
syscall(ffff80003c47b730) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c47b730) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9dff4dddcd0, count: 5
ddb{1}> trace
db_enter() at db_enter+0x25 sys/arch/amd64/amd64/db_interface.c:438
panic(ffffffff833d72da) at panic+0x1e5 sys/kern/subr_prf.c:198
ffs2_balloc(fffffd806a0f8270,40000000006,1,fffffd80097fd270,1,ffff80003c47b360) at ffs2_balloc+0x1961
ffs_truncate(fffffd806a0f8270,40000000007,0,fffffd80097fd270) at ffs_truncate+0x410 sys/ufs/ffs/ffs_inode.c:185
ufs_setattr(ffff80003c47b480) at ufs_setattr+0x8e9 sys/ufs/ufs/ufs_vnops.c:403
VOP_SETATTR(fffffd8066c8ab00,ffff80003c47b508,fffffd80097fd270,ffff80003c4682c8) at VOP_SETATTR+0x11b sys/kern/vfs_vops.c:210
dotruncate(ffff80003c4682c8,fffffd8066c8ab00,40000000007) at dotruncate+0x1da sys/kern/vfs_syscalls.c:2892
sys_ftruncate(ffff80003c4682c8,ffff80003c47b730,ffff80003c47b680) at sys_ftruncate+0x20a sys/kern/vfs_syscalls.c:2946
syscall(ffff80003c47b730) at syscall+0xb17 mi_syscall sys/sys/syscall_mi.h:176 [inline]
syscall(ffff80003c47b730) at syscall+0xb17 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0x9dff4dddcd0, count: -10

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/10 19:50 openbsd 411a0c209e89 4b3d9a38 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-multicore panic: ffs2_balloc: unwind failed
2026/04/03 13:32 openbsd de6be2070bf6 4b3d9a38 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main panic: ffs2_balloc: unwind failed
* Struck through repros no longer work on HEAD.