uvm_fault: softclock (6)

Status: upstream: reported on 2026/05/19 20:08
Reported-by: syzbot+da9c5223d70f4e23edb2@syzkaller.appspotmail.com
First crash: 67d, last: 64d
Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
openbsd uvm_fault: softclock (5) -1 1 692d 692d 0/4 auto-obsoleted due to no activity on 2024/12/01 02:13
openbsd uvm_fault: softclock (3) -1 1 1066d 1066d 0/4 auto-obsoleted due to no activity on 2023/11/22 14:27
openbsd uvm_fault: softclock -1 1 1376d 1376d 0/4 auto-obsoleted due to no activity on 2023/01/17 03:44
openbsd uvm_fault: softclock (4) -1 9 841d 872d 0/4 auto-obsoleted due to no activity on 2024/07/04 14:38
openbsd uvm_fault: softclock (2) -1 2 1235d 1248d 0/4 auto-obsoleted due to no activity on 2023/06/06 21:13

Sample crash report:
login: uvm_fault(0xfffffd806d4512f8, 0x8, 0, 2) -> e
kernel: page fault trap, code=2
Stopped at      softclock+0xe7: movq    %rcx,0x8(%rax)
    TID    PID    UID     PRFLAGS     PFLAGS  CPU  COMMAND
*407211  85816      0           0  0x4000000    0  syz-executor
softclock(0) at softclock+0xe7 sys/kern/kern_timeout.c:784
softintr_dispatch(0) at softintr_dispatch+0xf9 sys/kern/kern_softintr.c:87
dosoftint(0) at dosoftint+0x48 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
buf_get(0,0,ffd000) at buf_get+0x5de sys/kern/vfs_bio.c:1170
geteblk(ffd000) at geteblk+0x3c sys/kern/vfs_bio.c:-1
writedisklabel(d02,ffffffff83064980,ffff800000039000) at writedisklabel+0x4b sys/arch/amd64/amd64/disksubr.c:133
sdioctl(d01,84946467,ffff80000161b000,3,ffff800031cc8a88) at sdioctl+0x959 sys/scsi/sd.c:919
VOP_IOCTL(fffffd80719c9c28,84946467,ffff80000161b000,3,fffffd8007ffd548,ffff800031cc8a88) at VOP_IOCTL+0xa3 sys/kern/vfs_vops.c:264
vn_ioctl(fffffd806cc7ef00,84946467,ffff80000161b000,ffff800031cc8a88) at vn_ioctl+0xea sys/kern/vfs_vnops.c:537
sys_ioctl(ffff800031cc8a88,ffff80003c91d180,ffff80003c91d0d0) at sys_ioctl+0x660 sys/kern/sys_generic.c:-1
syscall(ffff80003c91d180) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c91d180) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xe0e3f43e1a0, count: 2
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> 
ddb> set $lines = 0
ddb> set $maxwidth = 0
ddb> show panic
*cpu0: uvm_fault(0xfffffd806d4512f8, 0x8, 0, 2) -> e
ddb> trace
softclock(0) at softclock+0xe7 sys/kern/kern_timeout.c:784
softintr_dispatch(0) at softintr_dispatch+0xf9 sys/kern/kern_softintr.c:87
dosoftint(0) at dosoftint+0x48 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
buf_get(0,0,ffd000) at buf_get+0x5de sys/kern/vfs_bio.c:1170
geteblk(ffd000) at geteblk+0x3c sys/kern/vfs_bio.c:-1
writedisklabel(d02,ffffffff83064980,ffff800000039000) at writedisklabel+0x4b sys/arch/amd64/amd64/disksubr.c:133
sdioctl(d01,84946467,ffff80000161b000,3,ffff800031cc8a88) at sdioctl+0x959 sys/scsi/sd.c:919
VOP_IOCTL(fffffd80719c9c28,84946467,ffff80000161b000,3,fffffd8007ffd548,ffff800031cc8a88) at VOP_IOCTL+0xa3 sys/kern/vfs_vops.c:264
vn_ioctl(fffffd806cc7ef00,84946467,ffff80000161b000,ffff800031cc8a88) at vn_ioctl+0xea sys/kern/vfs_vnops.c:537
sys_ioctl(ffff800031cc8a88,ffff80003c91d180,ffff80003c91d0d0) at sys_ioctl+0x660 sys/kern/sys_generic.c:-1
syscall(ffff80003c91d180) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c91d180) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xe0e3f43e1a0, count: -13
ddb> show registers
rdi                       0xffffffff
rsi                              0xd
rbp               0xffff80003c91ca20
rbx                              0x1
rdx               0xffff8000015e31c0
rcx               0xffffffff83a16fb0    timeout_todo
rax                                0
r8                0xffff80002c8aa060
r9                              0x21
r10               0x5af7510ab1ddd59c
r11               0x9243312be80570bb
r12                       0xffffffff
r13               0xffff80002a736b00
r14                                0
r15               0xffff80002a7672d0
rip               0xffffffff81c879b7    softclock+0xe7
cs                               0x8
rflags                       0x10246    __ALIGN_SIZE+0xf246
rsp               0xffff80003c91c9e0
ss                              0x10
softclock+0xe7: movq    %rcx,0x8(%rax)
ddb> show proc
PROC (syz-executor) tid=407211 pid=85816 tcnt=2 stat=onproc
    flags process=0 proc=4000000<THREAD>
    runpri=86, usrpri=86, slppri=17, nice=20
    wchan=0x0, wmesg=, ps_single=0x0 scnt=0 ecnt=0
    forw=0xffffffffffffffff, list=0xffff800031cc87f0,0xffffffff83a28f68
    process=0xffff8000ffffba98 user=0xffff80003c918000, vmspace=0xfffffd806d4512f8
    estcpu=36, cpticks=3, pctcpu=0.0, user=0, sys=3, intr=0
ddb> ps
   PID     TID   PPID    UID  S       FLAGS  WAIT          COMMAND
 85816  121212      0      0  3        0x80  fsleep        syz-executor
*85816  407211      0      0  7   0x4000000                syz-executor
  4984  272736      0      0  3        0x80  fsleep        syz-executor
  4984  499605      0      0  3   0x4000080  piperd        syz-executor
 82293  106255      0      0  3        0x80  fsleep        syz-executor
 82293   27308      0      0  3   0x4000080  sbwait        syz-executor
  5717  190627      0      0  3        0x80  fsleep        syz-executor
  5717  460025      0      0  3   0x4000080  lockf         syz-executor
 96718  517571  61724      0  3        0x80  fsleep        syz-executor
 96718  201685  61724      0  3   0x4000080  sbwait        syz-executor
  6004  424441      0      0  3        0x80  fsleep        syz-executor
  6004  414129      0      0  3   0x4000080  netacc        syz-executor
 38907  423302      0      0  3        0x80  fsleep        syz-executor
 38907   90803      0      0  3   0x4000080  fifor         syz-executor
 61724  236382      0      0  2       0xc82                syz-executor
 46415  448247      1      0  3    0x100083  ttyin         getty
 88804  208886      0      0  3     0x14200  acct          acct
ddb> show all locks
No such command
ddb> show malloc
           Type InUse  MemUse  HighUse   Limit  Requests Type Lim
         devbuf 11041  12131K   12574K 166960K     12810        0
            pcb    17     13K      14K 166960K       222        0
         rtable   244      9K       9K 166960K       440        0
             pf    35     14K      93K 166960K        78        0
         ifaddr    41      7K       7K 166960K        56        0
        ifgroup    47      1K       2K 166960K        73        0
         sysctl     4      1K       9K 166960K        11        0
       counters    33     17K      18K 166960K        40        0
       ioctlops     1      2K       4K 166960K       304        0
            iov     0      0K      12K 166960K        91        0
          mount     1      1K       1K 166960K         1        0
            log     0      0K       0K 166960K         4        0
         vnodes  1361     86K      86K 166960K      2104        0
      UFS quota     1     32K      32K 166960K         1        0
      UFS mount     5     36K      36K 166960K         5        0
            shm     2      1K       5K 166960K         6        0
         VM map     2      1K       1K 166960K         2        0
            sem    12      0K       1K 166960K        47        0
        dirhash    12      2K       2K 166960K        27        0
           ACPI  1692    195K     286K 166960K     12470        0
      file desc    18     65K      81K 166960K       751        0
          sigio     0      0K       0K 166960K         5        0
           proc    60     59K     100K 166960K       608        0
        subproc    72      4K       4K 166960K        81        0
    NFS srvsock     1      0K       0K 166960K         1        0
     NFS daemon     1     16K      16K 166960K         1        0
    ip_moptions     0      0K       0K 166960K        48        0
       in_multi    95      7K       7K 166960K       126        0
    ether_multi     1      0K       0K 166960K         3        0
            mrt     0      0K       0K 166960K        21        0
    ISOFS mount     1     32K      32K 166960K         1        0
  MSDOSFS mount     1     16K      16K 166960K         1        0
           ttys    73    334K     334K 166960K        73        0
           exec     0      0K       1K 166960K       434        0
   fusefs mount     1     32K      32K 166960K         1        0
     pfkey data     0      0K       0K 166960K         1        0
            tdb     3      0K       0K 166960K         3        0
        VM swap     8     62K      64K 166960K        10        0
       UVM amap   214    150K     168K 166960K      7962        0
       UVM aobj    14      2K       2K 166960K        15        0
     pinsyscall    39     78K      88K 166960K      1905        0
        memdesc     1      4K       4K 166960K         1        0
    crypto data     1      1K       1K 166960K         1        0
    ip6_options     0      0K       0K 166960K        22        0
            NDP    11      0K       1K 166960K        35        0
           temp    75   9116K    9180K 166960K     20162        0
         kqueue    14     22K      29K 166960K       124        0
      SYN cache     2     16K      16K 166960K         2        0
ddb> show all pools
Name      Size Requests Fail Releases Pgreq Pgrel Npage Hiwat Minpg Maxpg Idle
rtpcb      120       61    0       58     1     0     1     1     0     8    0
rtentry    136      132    0       25     4     0     4     4     0     8    0
unpcb      144      498    0      479     6     0     6     6     0     8    5
syncache   336        7    0        7     1     0     1     1     0     8    1
tcpqe       32        1    0        1     1     0     1     1     0     8    1
tcpcb      736      268    0      262     7     0     7     7     0     8    6
arp         96       20    0        2     1     0     1     1     0     8    0
ipq         40        2    0        0     1     0     1     1     0     8    0
ipqe        40        2    0        0     1     0     1     1     0     8    0
inpcb      328      855    0      843     7     0     7     7     0     8    5
ip6q        72        2    0        1     1     0     1     1     0     8    0
ip6af       40        2    0        2     1     0     1     1     0     8    1
nd6        112       34    0       10     1     0     1     1     0     8    0
pkpcb       40        3    0        3     1     0     1     1     0     8    1
kcovpl      48        9    0        1     1     0     1     1     0     8    0
ppxss      1072       3    0        3     1     0     1     1     0     8    1
pppxif     1416       1    0        1     1     0     1     1     0     8    1
pfstscr     40       10    0        8     1     0     1     1     0     8    0
pfrktable  1344       3    0        1     1     0     1     1     0     8    0
pfsrclim   320        1    0        1     1     0     1     1     0     8    1
pfstlim    224        1    0        1     1     0     1     1     0     8    1
pfanchor   1288       2    0        1     1     0     1     1     0     8    0
pftag       88        1    0        0     1     0     1     1     0     8    0
pfqueue    320        1    0        0     1     0     1     1     0     8    0
pfstitem    24        2    0        0     1     0     1     1     0     8    0
pfstkey    128       10    0        8     1     0     1     1     0     8    0
pfstate    384        5    0        4     1     0     1     1     0     8    0
pfrule     1360       9    0        7     1     0     1     1     0     8    0
rttmr      136        2    0        2     1     0     1     1     0     8    1
art_heap8  4096       1    0        0     1     0     1     1     0     8    0
art_heap4  256      579    0      124    32     0    32    32     0     8    3
art_table   40      580    0      124     6     0     6     6     0     8    1
art_node    32      132    0       34     1     0     1     1     0     8    0
sysvmsgpl   40        4    0        0     1     0     1     1     0     8    0
semupl     112        3    0        3     1     0     1     1     0     8    1
semapl      64       42    0       32     1     0     1     1     0     8    0
shmpl      112       12    0        1     1     0     1     1     0     8    0
dirhash    1024      27    0       10     3     0     3     3     0     8    0
dirhash: pool(0xffffffff83a26428:dirhash): free list modified: page 0xffff80002a778000; item ordinal 0; addr 0xffff80002a779000 (p 0xfffffd806e9f4000); offset 0x0=0x0
pool(dirhash): free list modified: page 0xffff80002a778000; item ordinal 0; addr 0xffff80002a779000 (p 0xfffffd806e9f4000); offset 0x0=0x0
dirhash: pool(0xffffffff83a26428:dirhash): page inconsistency: page 0xffff80002a778000; item ordinal 1; addr 0xea2fa1c6f6cb547f
dino2pl    256     2616    0     1155    92     0    92    92     0     8    0
ffsino     256     2616    0     1155    92     0    92    92     0     8    0
nchpl      144     3728    0     2030    64     0    64    64     0     8    0
vnodes     216     3242    0        0   181     0   181   181     0     8    0
namei      1024   11983    0    11983     2     0     2     2     0     8    2
namei: pool(0xffffffff83a075c0:namei): free list modified: page 0xffff80002a748000; item ordinal 0; addr 0xffff80002a749c00 (p 0xfffffd807f7e2000); offset 0x0=0x0
pool(namei): free list modified: page 0xffff80002a748000; item ordinal 0; addr 0xffff80002a749c00 (p 0xfffffd807f7e2000); offset 0x0=0x0
namei: pool(0xffffffff83a075c0:namei): page inconsistency: page 0xffff80002a748000; item ordinal 1; addr 0x8b1eef1b6225096d
pfiaddrpl  120        1    0        0     1     0     1     1     0     8    0
kstatmem   264       35    0       12     2     0     2     2     0     8    0
scsiplug    72        2    0        2     1     0     1     1     0     8    1
scxspl     216    17730    0    17730     8     0     8     8     1     8    8
plimitpl   152      250    0      233     1     0     1     1     0     8    0
sigapl     424     1051    0     1007     6     0     6     6     0     8    1
knotepl    120    25998    0    25946    17     7    10    17     0     8    8
kqueuepl   184      154    0      144     1     0     1     1     0     8    0
pipepl     304      223    0      195     3     0     3     3     0     8    0
fdescpl    448     1037    0     1007     4     0     4     4     0     8    0
filepl     120     5722    0     5501    14     0    14    14     0     8    6
lockfpl    104      407    0      403     1     0     1     1     0     8    0
lockfspl    48       90    0       87     1     0     1     1     0     8    0
sessionpl  144       41    0       32     1     0     1     1     0     8    0
pgrppl      48       59    0       42     1     0     1     1     0     8    0
ucredpl    104      767    0      755     1     0     1     1     0     8    0
zombiepl   144     1008    0     1007     1     0     1     1     0     8    0
processpl  1152    1051    0     1007     4     0     4     4     0     8    0
processpl: pool(0xffffffff83a29188:processpl): page inconsistency: page 0x0; at page head addr 0xffff80002a747f90 (p 0xffff80002a744000)
procpl     664     1947    0     1896     6     0     6     6     0     8    1
procpl: pool(0xffffffff83a28fd0:procpl): page inconsistency: page 0x0; at page head addr 0xffff80002a6edf90 (p 0xffff80002a6ec000)
procpl: pool(0xffffffff83a28fd0:procpl): page inconsistency: page 0x0; at page head addr 0xffff80002a737f90 (p 0xffff80002a736000)
sosppl     176        3    0        3     1     0     1     1     0     8    1
sockpl     552     1438    0     1404    14     4    10    14     0     8    7
mcl64k     65536     42    0       41     1     0     1     1     0     8    0
mcl8k      8192      17    0       17     1     0     1     1     0     8    1
mcl4k      4096    3418    0     3363    14     0    14    14     0     8    7
mcl2k      2048     641    0      640     3     0     3     3     0     8    2
mtagpl      96        5    0        5     1     0     1     1     0     8    1
mbufpl     256    10260    0    10088    15     0    15    15     0     8    2
bufpl      280     6342    0      126   445     0   445   445     0     8    0
anonpl      24   159646    0   156140    45     0    45    45     0   186   13
amapchunkpl 152   26310    0    25866    28     0    28    28     0   158    9
amappl16   200     2780    0     2731    18     4    14    15     0     8    8
amappl15   192       11    0       10     1     0     1     1     0     8    0
amappl14   184      425    0      424     1     0     1     1     0     8    0
amappl13   176      127    0      116     1     0     1     1     0     8    0
amappl12   168     1279    0     1250     2     0     2     2     0     8    0
amappl11   160        5    0        5     1     0     1     1     0     8    1
amappl10   152       82    0       72     1     0     1     1     0     8    0
amappl9    144      272    0      272     1     0     1     1     0     8    1
amappl8    136      123    0      121     1     0     1     1     0     8    0
amappl7    128      166    0      154     1     0     1     1     0     8    0
amappl6    120      159    0      157     1     0     1     1     0     8    0
amappl5    112      108    0       97     1     0     1     1     0     8    0
amappl4    104      279    0      262     1     0     1     1     0     8    0
amappl3     96     5324    0     5218     4     0     4     4     0     8    1
amappl2     88      570    0      515     2     0     2     2     0     8    0
amappl1     80    13647    0    13094    15     0    15    15     0     8    2
amappl      88     7144    0     6993     4     0     4     4     0    92    0
uvmvnodes   80      111    0        0     3     0     3     3     0     8    0
dma4096    4096       1    0        1     1     0     1     1     0     8    1
dma1024    1024       2    0        1     1     0     1     1     0     8    0
dma256     256        6    0        6     1     0     1     1     0     8    1
dma128     128      254    0      254     1     0     1     1     0     8    1
dma64       64        6    0        6     1     0     1     1     0     8    1
dma32       32        7    0        7     1     0     1     1     0     8    1
dma16       16       18    0       17     1     0     1     1     0     8    0
aobjpl      72       14    0        1     1     0     1     1     0     8    0
uaddrrnd    24     1037    0     1007     1     0     1     1     0     8    0
uaddrbest   32        2    0        0     1     0     1     1     0     8    0
uaddr       24     1037    0     1007     1     0     1     1     0     8    0
vmmpekpl   168     9988    0     9957     2     0     2     2     0     8    0
vmmpepl    168    73256    0    71419    92     0    92    92     0   357    7
vmsppl     368     1036    0     1007     4     0     4     4     0     8    1
rwobjpl     40    21969    0    20990    13     0    13    13     0     8    0
pdppl      4096    2080    0     2014    92    22    70    74     0     8    4
pvpl        32   445880    0   436094   115     0   115   115     0   265   24
pmappl     216     1036    0     1007     2     0     2     2     0     8    0
extentpl    40       45    0       27     1     0     1     1     0     8    0
phpool     112      368    0       22    10     0    10    10     0     8    0
ddb> machine ddbcpu 0
No such command
ddb> trace
softclock(0) at softclock+0xe7 sys/kern/kern_timeout.c:784
softintr_dispatch(0) at softintr_dispatch+0xf9 sys/kern/kern_softintr.c:87
dosoftint(0) at dosoftint+0x48 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
buf_get(0,0,ffd000) at buf_get+0x5de sys/kern/vfs_bio.c:1170
geteblk(ffd000) at geteblk+0x3c sys/kern/vfs_bio.c:-1
writedisklabel(d02,ffffffff83064980,ffff800000039000) at writedisklabel+0x4b sys/arch/amd64/amd64/disksubr.c:133
sdioctl(d01,84946467,ffff80000161b000,3,ffff800031cc8a88) at sdioctl+0x959 sys/scsi/sd.c:919
VOP_IOCTL(fffffd80719c9c28,84946467,ffff80000161b000,3,fffffd8007ffd548,ffff800031cc8a88) at VOP_IOCTL+0xa3 sys/kern/vfs_vops.c:264
vn_ioctl(fffffd806cc7ef00,84946467,ffff80000161b000,ffff800031cc8a88) at vn_ioctl+0xea sys/kern/vfs_vnops.c:537
sys_ioctl(ffff800031cc8a88,ffff80003c91d180,ffff80003c91d0d0) at sys_ioctl+0x660 sys/kern/sys_generic.c:-1
syscall(ffff80003c91d180) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c91d180) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xe0e3f43e1a0, count: -13
ddb> machine ddbcpu 1
No such command
ddb> trace
softclock(0) at softclock+0xe7 sys/kern/kern_timeout.c:784
softintr_dispatch(0) at softintr_dispatch+0xf9 sys/kern/kern_softintr.c:87
dosoftint(0) at dosoftint+0x48 sys/arch/amd64/amd64/intr.c:862
Xsoftclock() at Xsoftclock+0x27
buf_get(0,0,ffd000) at buf_get+0x5de sys/kern/vfs_bio.c:1170
geteblk(ffd000) at geteblk+0x3c sys/kern/vfs_bio.c:-1
writedisklabel(d02,ffffffff83064980,ffff800000039000) at writedisklabel+0x4b sys/arch/amd64/amd64/disksubr.c:133
sdioctl(d01,84946467,ffff80000161b000,3,ffff800031cc8a88) at sdioctl+0x959 sys/scsi/sd.c:919
VOP_IOCTL(fffffd80719c9c28,84946467,ffff80000161b000,3,fffffd8007ffd548,ffff800031cc8a88) at VOP_IOCTL+0xa3 sys/kern/vfs_vops.c:264
vn_ioctl(fffffd806cc7ef00,84946467,ffff80000161b000,ffff800031cc8a88) at vn_ioctl+0xea sys/kern/vfs_vnops.c:537
sys_ioctl(ffff800031cc8a88,ffff80003c91d180,ffff80003c91d0d0) at sys_ioctl+0x660 sys/kern/sys_generic.c:-1
syscall(ffff80003c91d180) at syscall+0x962 mi_syscall sys/sys/syscall_mi.h:-1 [inline]
syscall(ffff80003c91d180) at syscall+0x962 sys/arch/amd64/amd64/trap.c:783
Xsyscall() at Xsyscall+0x128
end of kernel
end trace frame: 0xe0e3f43e1a0, count: -13

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/05/23 00:41 openbsd dbd5cf8c5e8a c69befb3 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: softclock
2026/05/19 20:07 openbsd 3fe334830a75 340bcdf0 .config console log report [disk image] [bsd.gdb] [kernel image] ci-openbsd-main uvm_fault: softclock
* Struck through repros no longer work on HEAD.