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INFO: task hung in dbAlloc

Status: upstream: reported C repro on 2025/10/23 21:21
Subsystems: jfs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+a2bef7ebecf9cb8b880a@syzkaller.appspotmail.com
First crash: 214d, last: 45d
Cause bisection: the cause commit could be any of (bisect log):
  be503db4d0f2 vsprintf: simplify number handling
  03d23941bf03 vsprintf: avoid nested switch statement on same variable
   
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
01e9e2af-4d66-4c3c-b6a4-ccedf9a008ff assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ INFO: task hung in dbAlloc 2026/05/18 08:01 2026/05/18 08:01 2026/05/18 08:59 de5aae85e5f28e2fa1c7deefcc24fe286abe5140
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [jfs?] INFO: task hung in dbAlloc 0 (1) 2025/10/23 21:21
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/04/10 10:14 25m retest repro linux-next report log
2026/04/10 10:14 21m retest repro linux-next report log
2026/04/10 10:14 30m retest repro linux-next report log
2026/04/10 10:14 21m retest repro linux-next report log
2026/03/27 06:47 24m retest repro linux-next report log
2026/03/27 06:47 21m retest repro linux-next report log
2026/03/27 06:35 21m retest repro linux-next report log
2026/01/30 08:29 21m retest repro linux-next report log
2026/01/30 08:09 21m retest repro linux-next report log
2026/01/16 05:02 30m retest repro linux-next report log

Sample crash report:
INFO: task syz.2.19:6128 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.19        state:D
 stack:24856 pid:6128  tgid:6127  ppid:5976   task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5254 [inline]
 __schedule+0x17c4/0x4d60 kernel/sched/core.c:6862
 __schedule_loop kernel/sched/core.c:6944 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6959
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7016
 __down_read_common kernel/locking/rwsem.c:1261 [inline]
 __down_read kernel/locking/rwsem.c:1274 [inline]
 down_read_nested+0x9a/0x2f0 kernel/locking/rwsem.c:1663
 dbAlloc+0x3a7/0xba0 fs/jfs/jfs_dmap.c:790
 diNewExt+0x9af/0x3150 fs/jfs/jfs_imap.c:2261
 diAllocExt fs/jfs/jfs_imap.c:1952 [inline]
 diAllocAG+0xe86/0x1df0 fs/jfs/jfs_imap.c:1669
 diAlloc+0x1d5/0x1680 fs/jfs/jfs_imap.c:1590
 ialloc+0x8c/0x8f0 fs/jfs/jfs_inode.c:56
 __do_sys_mkdirat fs/namei.c:4503 [inline]
 __se_sys_mkdirat fs/namei.c:4501 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa65298efc9
RSP: 002b:00007fa6538ef038 EFLAGS: 00000246
 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fa652be5fa0 RCX: 00007fa65298efc9
RDX: 0000000000000408 RSI: 0000200000000300 RDI: 0000000000000004
RBP: 00007fa652a11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa652be6038 R14: 00007fa652be5fa0 R15: 00007ffd16b4c6d8
 </TASK>
INFO: task syz.4.21:6134 blocked for more than 144 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.4.21        state:D
 stack:25704 pid:6134  tgid:6133  ppid:5980   task_flags:0x400140 flags:0x00080003
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5254 [inline]
 __schedule+0x17c4/0x4d60 kernel/sched/core.c:6862
 __schedule_loop kernel/sched/core.c:6944 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:6959
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7016
 rwsem_down_read_slowpath+0x5fd/0x8f0 kernel/locking/rwsem.c:1086
 dbAlloc+0x3a7/0xba0 fs/jfs/jfs_dmap.c:790
 diNewExt+0x9af/0x3150 fs/jfs/jfs_imap.c:2261
 diAllocExt fs/jfs/jfs_imap.c:1952 [inline]
 diAllocAG+0xe86/0x1df0 fs/jfs/jfs_imap.c:1669
 diAlloc+0x1d5/0x1680 fs/jfs/jfs_imap.c:1590
 jfs_mkdir+0x193/0xa70 fs/jfs/namei.c:225
 vfs_mkdir+0x306/0x510 fs/namei.c:4453
 do_mkdirat+0x247/0x590 fs/namei.c:4486
 __do_sys_mkdirat fs/namei.c:4503 [inline]
 __se_sys_mkdirat fs/namei.c:4501 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbe3ed8efc9
RSP: 002b:00007fbe3fcc9038 EFLAGS: 00000246
 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fbe3efe5fa0 RCX: 00007fbe3ed8efc9

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/24 00:04 linux-next aaa9c3550b60 c0460fcd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
2025/10/23 19:03 linux-next aaa9c3550b60 c0460fcd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
2025/10/23 14:04 linux-next aaa9c3550b60 c0460fcd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
2025/10/23 21:26 linux-next aaa9c3550b60 c0460fcd .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
2025/10/23 16:28 linux-next aaa9c3550b60 c0460fcd .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
2025/10/23 11:17 linux-next aaa9c3550b60 c0460fcd .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
2025/10/23 08:46 linux-next aaa9c3550b60 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in dbAlloc
* Struck through repros no longer work on HEAD.