syzbot

 sign-in | mailing list | source | docs
🐞 Open [87]
🐞 Fixed [11]
🐞 Invalid [96]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap
💬 Send us feedback

INFO: task hung in fuse_flush (2)

Status: premoderation: reported on 2026/03/28 15:06
Reported-by: syzbot+9d657051ee1aa9362378@syzkaller.appspotmail.com
First crash: 1d04h, last: 1d04h
▶ ▼ Similar bugs (14)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-12 INFO: task hung in fuse_flush 1 2 161d 191d 0/1 auto-obsoleted due to no activity on 2026/01/16 20:08
upstream INFO: task hung in fuse_flush (5) fuse 1 3 384d 389d 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 1837d 1837d 0/1 auto-closed as invalid on 2021/07/16 16:14
linux-6.1 INFO: task hung in fuse_flush 1 1 394d 394d 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 1160d 1169d 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 497d 643d 0/29 auto-obsoleted due to no activity on 2025/02/15 08:56
upstream INFO: task hung in fuse_flush fuse 1 2 1605d 1693d 0/29 auto-closed as invalid on 2022/02/03 03:15
linux-6.1 INFO: task hung in fuse_flush (2) 1 1 293d 293d 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 644d 644d 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 1645d 1645d 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 1201d 1522d 0/1 upstream: reported C repro on 2022/01/26 21:17
linux-4.19 INFO: task hung in fuse_flush (3) 1 109 1160d 1522d 0/1 upstream: reported on 2022/01/27 11:57
upstream INFO: task hung in fuse_flush (3) fuse 1 1 913d 913d 0/29 auto-obsoleted due to no activity on 2023/12/26 21:09
linux-6.6 INFO: task hung in fuse_flush 1 1 46d 46d 0/2 upstream: reported on 2026/02/10 19:58

Sample crash report:
INFO: task syz.0.1831:4776 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1831      state:D stack:0     pid:4776  tgid:4776  ppid:1158   flags:0x00000006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6016 [inline]
 __schedule+0x1399/0x1fa0 kernel/sched/core.c:7870
 __schedule_loop kernel/sched/core.c:7951 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7966
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:8023
 rwsem_down_write_slowpath+0x5b0/0x1bb0 kernel/locking/rwsem.c:1239
 __down_write_common kernel/locking/rwsem.c:1383 [inline]
 __down_write kernel/locking/rwsem.c:1392 [inline]
 down_write+0x163/0x2b0 kernel/locking/rwsem.c:1659
 inode_lock include/linux/fs.h:817 [inline]
 fuse_flush+0x799/0x2020 fs/fuse/file.c:580
 filp_flush fs/open.c:1552 [inline]
 filp_close+0xc0/0x160 fs/open.c:1565
 __range_close fs/file.c:726 [inline]
 __close_range+0x32a/0x4c0 fs/file.c:792
 __do_sys_close_range fs/open.c:1618 [inline]
 __se_sys_close_range fs/open.c:1615 [inline]
 __x64_sys_close_range+0x7e/0x90 fs/open.c:1615
 x64_sys_call+0x1686/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:437
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f9d9c19c819
RSP: 002b:00007ffe6c472758 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007f9d9c417da0 RCX: 00007f9d9c19c819
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f9d9c417da0 R08: 0000000000000006 R09: 0000000000000000
R10: 00007f9d9c417cb0 R11: 0000000000000246 R12: 00000000000230cf
R13: 00007f9d9c415fac R14: 0000000000022df8 R15: 00007ffe6c472860
 </TASK>
INFO: task syz.0.1831:4777 blocked for more than 123 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.1831      state:D stack:0     pid:4777  tgid:4776  ppid:1158   flags:0x00000004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:6016 [inline]
 __schedule+0x1399/0x1fa0 kernel/sched/core.c:7870
 __schedule_loop kernel/sched/core.c:7951 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7966
 schedule_timeout+0xc7/0x3b0 kernel/time/timer.c:2596
 do_wait_for_common kernel/sched/completion.c:95 [inline]
 __wait_for_common kernel/sched/completion.c:116 [inline]
 wait_for_common+0x369/0x650 kernel/sched/completion.c:127
 wait_for_completion+0x1c/0x40 kernel/sched/completion.c:148
 fuse_direct_IO+0xa05/0x1310 fs/fuse/file.c:3268
 fuse_direct_write_iter fs/fuse/file.c:1790 [inline]
 fuse_file_write_iter+0x1653/0x2830 fs/fuse/file.c:1865
 aio_write+0x4e5/0x720 fs/aio.c:1633
 __io_submit_one fs/aio.c:-1 [inline]
 io_submit_one+0xc5d/0x1980 fs/aio.c:2052
 __do_sys_io_submit fs/aio.c:2111 [inline]
 __se_sys_io_submit+0x17f/0x3f0 fs/aio.c:2081
 __x64_sys_io_submit+0x7f/0xa0 fs/aio.c:2081
 x64_sys_call+0x1c95/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:210
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f9d9c19c819
RSP: 002b:00007f9d9d0cd028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007f9d9c415fa0 RCX: 00007f9d9c19c819
RDX: 0000200000000780 RSI: 0000000000000020 RDI: 00007f9d9d083000
RBP: 00007f9d9c232c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9d9c416038 R14: 00007f9d9c415fa0 R15: 00007ffe6c4725f8
 </TASK>
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 9f86d9c18f1652eb5f7cacfb207b3899f57a91b2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/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+0xdad/0xf00 kernel/hung_task.c:423
 kthread+0x2c9/0x370 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 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Not tainted syzkaller #0 9f86d9c18f1652eb5f7cacfb207b3899f57a91b2
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:pv_native_safe_halt+0x13/0x20 arch/x86/kernel/paravirt.c:106
Code: cc cc cc cc cc cc cc b8 a7 31 69 4b 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 53 4b 46 00 55 48 89 e5 fb f4 <5d> c3 cc cc cc cc cc cc cc cc cc cc cc b8 00 00 00 00 90 90 90 90
RSP: 0018:ffffc900001a7e00 EFLAGS: 000002c6
RAX: ffff8881f6f00000 RBX: ffff88810366df00 RCX: ffffffff85a10bcd
RDX: 0000000000000001 RSI: 0000000000000004 RDI: 00000000005a0674
RBP: ffffc900001a7e00 R08: ffff8881f6f39773 R09: 1ffff1103ede72ee
R10: dffffc0000000000 R11: ffffed103ede72ef R12: 1ffff110206cdbe0
R13: 0000000000000001 R14: 0000000000000000 R15: ffffffff87ec0868
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555923e1908 CR3: 0000000143438000 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+0x3e/0x80 kernel/sched/idle.c:117
 cpuidle_idle_call kernel/sched/idle.c:185 [inline]
 do_idle+0x19f/0x4b0 kernel/sched/idle.c:326
 cpu_startup_entry+0x47/0x60 kernel/sched/idle.c:424
 start_secondary+0x12e/0x140 arch/x86/kernel/smpboot.c:314
 common_startup_64+0x13b/0x157
 </TASK>
ip6_tunnel:  xmit: Local address not yet configured!

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/03/28 15:05 android16-6.12 2dda9e2ebc9a b5ceaad2 .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.