syzbot


INFO: task hung in fuse_flush

Status: upstream: reported on 2025/02/28 05:58
Reported-by: syzbot+ff458f8198ba68f6fb5f@syzkaller.appspotmail.com
First crash: 12d, last: 12d
Similar bugs (9)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 INFO: task hung in fuse_flush 1 1454d 1454d 0/1 auto-closed as invalid on 2021/07/16 16:14
upstream INFO: task hung in fuse_flush (2) fuse 2 778d 787d 0/28 auto-obsoleted due to no activity on 2023/04/24 00:25
upstream INFO: task hung in fuse_flush (4) fuse 6 115d 261d 0/28 auto-obsoleted due to no activity on 2025/02/15 08:56
upstream INFO: task hung in fuse_flush fuse 2 1223d 1311d 0/28 auto-closed as invalid on 2022/02/03 03:15
linux-5.15 INFO: task hung in fuse_flush 1 262d 262d 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 1263d 1263d 0/1 auto-closed as invalid on 2022/01/24 04:40
linux-4.14 INFO: task hung in fuse_flush C inconclusive 19 819d 1140d 0/1 upstream: reported C repro on 2022/01/26 21:17
linux-4.19 INFO: task hung in fuse_flush (3) 109 777d 1140d 0/1 upstream: reported on 2022/01/27 11:57
upstream INFO: task hung in fuse_flush (3) fuse 1 531d 531d 0/28 auto-obsoleted due to no activity on 2023/12/26 21:09

Sample crash report:
INFO: task syz.2.672:7059 blocked for more than 144 seconds.
      Not tainted 6.1.129-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.672       state:D stack:25864 pid:7059  ppid:4251   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5243 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6560
 schedule+0xbf/0x180 kernel/sched/core.c:6636
 rwsem_down_write_slowpath+0xea1/0x14b0 kernel/locking/rwsem.c:1189
 inode_lock include/linux/fs.h:758 [inline]
 fuse_flush+0x274/0x950 fs/fuse/file.c:499
 filp_close+0xae/0x150 fs/open.c:1431
 __range_close fs/file.c:697 [inline]
 __close_range+0x597/0x7d0 fs/file.c:747
 __do_sys_close_range fs/open.c:1476 [inline]
 __se_sys_close_range fs/open.c:1473 [inline]
 __x64_sys_close_range+0x76/0x80 fs/open.c:1473
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6765f8d169
RSP: 002b:00007ffdc3633a78 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: ffffffffffffffda RBX: 00007f67661a7ba0 RCX: 00007f6765f8d169
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 00007f67661a7ba0 R08: 00000000000000e0 R09: 0000000dc3633d6f
R10: 00007f67661a7ac0 R11: 0000000000000246 R12: 0000000000054cc2
R13: 00007ffdc3633b70 R14: ffffffffffffffff R15: 00007ffdc3633b90
 </TASK>
INFO: task syz.2.672:7063 blocked for more than 144 seconds.
      Not tainted 6.1.129-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.2.672       state:D stack:25168 pid:7063  ppid:4251   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5243 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6560
 schedule+0xbf/0x180 kernel/sched/core.c:6636
 fuse_set_nowrite+0x212/0x340 fs/fuse/dir.c:1601
 fuse_sync_writes fs/fuse/file.c:476 [inline]
 fuse_fsync+0x14e/0x2f0 fs/fuse/file.c:578
 generic_write_sync include/linux/fs.h:2962 [inline]
 generic_file_write_iter+0x29d/0x310 mm/filemap.c:4009
 fuse_cache_write_iter fs/fuse/file.c:1320 [inline]
 fuse_file_write_iter+0xb87/0x10e0 fs/fuse/file.c:1656
 call_write_iter include/linux/fs.h:2265 [inline]
 aio_write+0x561/0x780 fs/aio.c:1615
 io_submit_one+0x768/0x18d0 fs/aio.c:2034
 __do_sys_io_submit fs/aio.c:2093 [inline]
 __se_sys_io_submit+0x17b/0x2f0 fs/aio.c:2063
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f6765f8d169
RSP: 002b:00007f6765dde038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1
RAX: ffffffffffffffda RBX: 00007f67661a6160 RCX: 00007f6765f8d169
RDX: 0000400000000700 RSI: 000000000000140b RDI: 00007f6766ce5000
RBP: 00007f676600e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f67661a6160 R15: 00007ffdc3633918
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d32e850 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d32f050 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/27:
 #0: ffffffff8d32e680 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d32e680 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d32e680 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6510
2 locks held by getty/4012:
 #0: ffff88814cc1b098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc9000325e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x54a/0x1620 drivers/tty/n_tty.c:2198
1 lock held by syz.2.672/7059:
 #0: ffff888055a12310 (&sb->s_type->i_mutex_key#26){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #0: ffff888055a12310 (&sb->s_type->i_mutex_key#26){+.+.}-{3:3}, at: fuse_flush+0x274/0x950 fs/fuse/file.c:499
1 lock held by syz.2.672/7063:
 #0: ffff888055a12310 (&sb->s_type->i_mutex_key#26){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #0: ffff888055a12310 (&sb->s_type->i_mutex_key#26){+.+.}-{3:3}, at: fuse_fsync+0x10e/0x2f0 fs/fuse/file.c:567

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted 6.1.129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1ca/0x430 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf88/0xfd0 kernel/hung_task.c:377
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 8425 Comm: syz.1.1034 Not tainted 6.1.129-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
RIP: 0010:__sanitizer_cov_trace_const_cmp4+0x0/0x80 kernel/kcov.c:314
Code: 39 c8 77 22 89 f8 89 f6 49 ff c2 4c 89 11 48 c7 44 0a 08 03 00 00 00 48 89 44 0a 10 48 89 74 0a 18 4c 89 44 0a 20 c3 0f 1f 00 <4c> 8b 04 24 65 48 8b 15 04 d5 77 7e 65 8b 05 05 d5 77 7e 25 00 01
RSP: 0018:ffffc900001e0eb0 EFLAGS: 00000046
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88802c889dc0
RDX: 0000000000010000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff8880b8f2a6a8 R08: ffffffff817cd610 R09: fffffbfff1d413e6
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000007478080d80
R13: ffff8880b8f2a4c0 R14: dffffc0000000000 R15: ffff8880b8f2a8a8
FS:  0000000000000000(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c428ca2 CR3: 0000000029384000 CR4: 00000000003506e0
DR0: 0000000000000050 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <IRQ>
 hrtimer_interrupt+0x551/0x980 kernel/time/hrtimer.c:1828
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1107 [inline]
 __sysvec_apic_timer_interrupt+0x158/0x5b0 arch/x86/kernel/apic/apic.c:1124
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0x9b/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:page_remove_rmap+0x1/0xed0 mm/rmap.c:1425
Code: 00 48 8b 03 83 e0 01 eb 0a e8 7b 86 b7 ff b8 01 00 00 00 5b 41 5c 41 5e 41 5f c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 55 <41> 57 41 56 41 55 41 54 53 48 83 ec 28 41 89 d5 49 89 f7 49 89 fc
RSP: 0018:ffffc900045cf310 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffffc900045cf4a0 RCX: ffffc900045cf4a0
RDX: 0000000000000000 RSI: ffff888027791360 RDI: ffffea0001743140
RBP: ffffc900045cf510 R08: ffffffff81cd06de R09: fffff940002e8629
R10: 0000000000000000 R11: dffffc0000000001 R12: ffffea0001743140
R13: dffffc0000000000 R14: 1ffffd40002e8629 R15: ffffea0001743148
 zap_pte_range mm/memory.c:1453 [inline]
 zap_pmd_range mm/memory.c:1574 [inline]
 zap_pud_range mm/memory.c:1603 [inline]
 zap_p4d_range mm/memory.c:1624 [inline]
 unmap_page_range+0x1217/0x2740 mm/memory.c:1645
 unmap_vmas+0x48b/0x640 mm/memory.c:1730
 exit_mmap+0x249/0x980 mm/mmap.c:3238
 __mmput+0x115/0x3c0 kernel/fork.c:1200
 exit_mm+0x226/0x300 kernel/exit.c:565
 do_exit+0x9f1/0x26a0 kernel/exit.c:858
 do_group_exit+0x202/0x2b0 kernel/exit.c:1021
 get_signal+0x16cb/0x17a0 kernel/signal.c:2871
 arch_do_signal_or_restart+0xb0/0x1a10 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x6a/0x100 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:303
 do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:87
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fdb1b98d169
Code: Unable to access opcode bytes at 0x7fdb1b98d13f.
RSP: 002b:00007fdb1c8a9038 EFLAGS: 00000246 ORIG_RAX: 000000000000012b
RAX: 0000000000010106 RBX: 00007fdb1bba6080 RCX: 00007fdb1b98d169
RDX: 0000000000010106 RSI: 00004000000000c0 RDI: 0000000000000006
RBP: 00007fdb1ba0e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fdb1bba6080 R15: 00007fff5d3cf728
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/02/28 05:57 linux-6.1.y 3a8358583626 6a8fcbc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in fuse_flush
* Struck through repros no longer work on HEAD.