syzbot

 sign-in | mailing list | source | docs
🐞 Open [106]
🐞 Fixed [6]
🐞 Invalid [4]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap
💬 Send us feedback

INFO: task hung in fuse_flush

Status: premoderation: reported on 2025/09/19 18:32
Reported-by: syzbot+0c97f86230db6bfd70e0@syzkaller.appspotmail.com
First crash: 14h24m, last: 14h24m
▶ ▼ Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in fuse_flush (5) fuse 1 3 193d 198d 0/29 auto-obsoleted due to no activity on 2025/06/08 10:49
linux-4.19 INFO: task hung in fuse_flush 1 1 1646d 1646d 0/1 auto-closed as invalid on 2021/07/16 16:14
linux-6.1 INFO: task hung in fuse_flush 1 1 204d 204d 0/3 auto-obsoleted due to no activity on 2025/06/08 05:58
upstream INFO: task hung in fuse_flush (2) fuse 1 2 970d 979d 0/29 auto-obsoleted due to no activity on 2023/04/24 00:25
upstream INFO: task hung in fuse_flush (4) fuse 1 6 307d 453d 0/29 auto-obsoleted due to no activity on 2025/02/15 08:56
upstream INFO: task hung in fuse_flush fuse 1 2 1415d 1503d 0/29 auto-closed as invalid on 2022/02/03 03:15
linux-6.1 INFO: task hung in fuse_flush (2) 1 1 102d 102d 0/3 auto-obsoleted due to no activity on 2025/09/17 09:24
linux-5.15 INFO: task hung in fuse_flush 1 1 454d 454d 0/3 auto-obsoleted due to no activity on 2024/09/30 23:08
linux-4.19 INFO: task hung in fuse_flush (2) 1 1 1455d 1455d 0/1 auto-closed as invalid on 2022/01/24 04:40
linux-4.14 INFO: task hung in fuse_flush 1 C inconclusive 19 1011d 1332d 0/1 upstream: reported C repro on 2022/01/26 21:17
linux-4.19 INFO: task hung in fuse_flush (3) 1 109 969d 1331d 0/1 upstream: reported on 2022/01/27 11:57
upstream INFO: task hung in fuse_flush (3) fuse 1 1 723d 723d 0/29 auto-obsoleted due to no activity on 2023/12/26 21:09

Sample crash report:
INFO: task syz.9.12925:10047 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.12925     state:D stack:0     pid:10047 tgid:10045 ppid:6984   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7944
 rwsem_down_write_slowpath+0x9e8/0x1b90 kernel/locking/rwsem.c:1239
 __down_write_common kernel/locking/rwsem.c:1383 [inline]
 __down_write kernel/locking/rwsem.c:1392 [inline]
 down_write+0x152/0x2a0 kernel/locking/rwsem.c:1659
 inode_lock include/linux/fs.h:815 [inline]
 fuse_flush+0x607/0x1d50 fs/fuse/file.c:560
 filp_flush fs/open.c:1550 [inline]
 filp_close+0xbd/0x160 fs/open.c:1563
 __range_close fs/file.c:712 [inline]
 __close_range+0x50e/0x6c0 fs/file.c:769
 __do_sys_close_range fs/open.c:1616 [inline]
 __se_sys_close_range fs/open.c:1613 [inline]
 __x64_sys_close_range+0x7e/0x90 fs/open.c:1613
 x64_sys_call+0x1686/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:437
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f7f3f98ec29
RSP: 002b:00007f7f3e3f7038 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007f7f3fbd6090 RCX: 00007f7f3f98ec29
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000006
RBP: 00007f7f3fa11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f3fbd6128 R14: 00007f7f3fbd6090 R15: 00007ffc700f69a8
 </TASK>
INFO: task syz.9.12925:10048 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.9.12925     state:D stack:0     pid:10048 tgid:10045 ppid:6984   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5945 [inline]
 __schedule+0x1322/0x1df0 kernel/sched/core.c:7791
 __schedule_loop kernel/sched/core.c:7872 [inline]
 schedule+0xc6/0x240 kernel/sched/core.c:7887
 fuse_set_nowrite+0x1cd/0x310 fs/fuse/dir.c:2129
 fuse_sync_writes fs/fuse/file.c:526 [inline]
 fuse_fsync+0x510/0x18f0 fs/fuse/file.c:650
 vfs_fsync_range+0x180/0x3a0 fs/sync.c:194
 generic_write_sync include/linux/fs.h:2888 [inline]
 generic_file_write_iter+0x286/0x310 mm/filemap.c:4262
 fuse_cache_write_iter fs/fuse/file.c:1489 [inline]
 fuse_file_write_iter+0x1676/0x25e0 fs/fuse/file.c:1840
 do_iter_readv_writev+0x4f2/0x6a0 fs/read_write.c:-1
 vfs_writev+0x485/0xcf0 fs/read_write.c:1076
 do_writev+0x14d/0x2d0 fs/read_write.c:1123
 __do_sys_writev fs/read_write.c:1196 [inline]
 __se_sys_writev fs/read_write.c:1193 [inline]
 __x64_sys_writev+0x81/0x90 fs/read_write.c:1193
 x64_sys_call+0x1fbb/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:21
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x58/0xf0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f7f3f98ec29
RSP: 002b:00007f7f3e3d6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007f7f3fbd6180 RCX: 00007f7f3f98ec29
RDX: 0000000000000001 RSI: 0000200000000000 RDI: 0000000000000006
RBP: 00007f7f3fa11e41 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f3fbd6218 R14: 00007f7f3fbd6180 R15: 00007ffc700f69a8
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 33840401dc9524e2de0309c027e288ea06768364
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x10c/0x190 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2bf/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xd8f/0xed0 kernel/hung_task.c:423
 kthread+0x2c7/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted syzkaller #0 33840401dc9524e2de0309c027e288ea06768364
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:pv_native_safe_halt+0x17/0x20 arch/x86/kernel/paravirt.c:106
Code: cc cc cc b8 eb db 9a 6b 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 93 d1 3a 00 f3 0f 1e fa 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff87207da0 EFLAGS: 000002c6
RAX: ffff8881f6e00000 RBX: ffffffff87215540 RCX: ffffffff858c80ae
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000017b0614
RBP: ffffffff87207da0 R08: ffff8881f6e39733 R09: 1ffff1103edc72e6
R10: dffffc0000000000 R11: ffffed103edc72e7 R12: 1ffffffff0e42aa8
R13: 0000000000000000 R14: 0000000000000000 R15: ffffffff87cb1728
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbfa11a4198 CR3: 00000001016fc000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 arch_safe_halt arch/x86/include/asm/paravirt.h:112 [inline]
 default_idle+0x17/0x30 arch/x86/kernel/process.c:754
 arch_cpu_idle+0xd/0x20 arch/x86/kernel/process.c:791
 default_idle_call+0x3f/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x1a0/0x470 kernel/sched/idle.c:326
 cpu_startup_entry+0x48/0x70 kernel/sched/idle.c:424
 rest_init+0x10b/0x130 init/main.c:748
 start_kernel+0x46a/0x4bb init/main.c:1135
 x86_64_start_reservations+0x2e/0x30 arch/x86/kernel/head64.c:507
 x86_64_start_kernel+0x6a/0x7b arch/x86/kernel/head64.c:488
 common_startup_64+0x13b/0x157
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/19 18:31 android16-6.12 749cf1743eb2 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in fuse_flush
* Struck through repros no longer work on HEAD.