syzbot


INFO: task hung in fuse_set_nowrite

Status: upstream: reported on 2025/07/06 03:33
Reported-by: syzbot+d5e79ce4d77f082edf01@syzkaller.appspotmail.com
First crash: 59d, last: 59d
Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in fuse_set_nowrite (2) fuse 1 1 183d 183d 0/29 auto-obsoleted due to no activity on 2025/06/01 13:09
upstream INFO: task hung in fuse_set_nowrite fuse 1 1 354d 354d 0/29 auto-obsoleted due to no activity on 2024/12/12 21:26

Sample crash report:
INFO: task syz.3.306:5495 blocked for more than 144 seconds.
      Not tainted 6.1.142-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.306       state:D stack:0     pid:5495  ppid:4307   flags:0x0000000d
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 schedule+0xc4/0x170 kernel/sched/core.c:6637
 fuse_set_nowrite+0x198/0x2c4 fs/fuse/dir.c:1603
 fuse_sync_writes fs/fuse/file.c:476 [inline]
 fuse_flush+0x230/0x6a0 fs/fuse/file.c:500
 filp_close+0xb0/0x160 fs/open.c:1431
 __range_close fs/file.c:705 [inline]
 __close_range+0x4ec/0x68c fs/file.c:755
 __do_sys_close_range fs/open.c:1476 [inline]
 __se_sys_close_range fs/open.c:1473 [inline]
 __arm64_sys_close_range+0x7c/0x94 fs/open.c:1473
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
INFO: task syz.3.306:5501 blocked for more than 144 seconds.
      Not tainted 6.1.142-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.306       state:D stack:0     pid:5501  ppid:4307   flags:0x00000009
Call trace:
 __switch_to+0x2f4/0x568 arch/arm64/kernel/process.c:555
 context_switch kernel/sched/core.c:5244 [inline]
 __schedule+0xdd4/0x1b2c kernel/sched/core.c:6561
 schedule+0xc4/0x170 kernel/sched/core.c:6637
 rwsem_down_write_slowpath+0xb74/0x125c kernel/locking/rwsem.c:1189
 __down_write_common kernel/locking/rwsem.c:1314 [inline]
 __down_write kernel/locking/rwsem.c:1323 [inline]
 down_write+0x84/0x88 kernel/locking/rwsem.c:1574
 inode_lock include/linux/fs.h:758 [inline]
 fuse_fsync+0xf0/0x2b8 fs/fuse/file.c:567
 vfs_fsync_range+0x168/0x188 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2962 [inline]
 generic_file_write_iter+0x224/0x2b0 mm/filemap.c:4010
 fuse_cache_write_iter fs/fuse/file.c:1320 [inline]
 fuse_file_write_iter+0x89c/0xd08 fs/fuse/file.c:1656
 do_iter_readv_writev fs/read_write.c:-1 [inline]
 do_iter_write+0x530/0x91c fs/read_write.c:861
 vfs_writev fs/read_write.c:934 [inline]
 do_writev+0x1e0/0x380 fs/read_write.c:977
 __do_sys_writev fs/read_write.c:1050 [inline]
 __se_sys_writev fs/read_write.c:1047 [inline]
 __arm64_sys_writev+0x80/0x94 fs/read_write.c:1047
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x138 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffff800015287770 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffff800015287f90 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x40/0xbb4 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffff800015286e00 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:349
1 lock held by udevd/3923:
 #0: ffff00019f703198 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested kernel/sched/core.c:537 [inline]
 #0: ffff00019f703198 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock kernel/sched/sched.h:1355 [inline]
 #0: ffff00019f703198 (&rq->__lock){-.-.}-{2:2}, at: rq_lock kernel/sched/sched.h:1645 [inline]
 #0: ffff00019f703198 (&rq->__lock){-.-.}-{2:2}, at: __schedule+0x2b8/0x1b2c kernel/sched/core.c:6477
2 locks held by getty/4076:
 #0: ffff0000d6cd5098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80001ce762f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x2ec/0xf9c drivers/tty/n_tty.c:2198
2 locks held by syz-executor/4295:
2 locks held by kworker/0:10/4928:
 #0: ffff0000c0021938 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff8000213e7c20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267
1 lock held by syz.3.306/5495:
 #0: ffff0000f5c70150 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #0: ffff0000f5c70150 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: fuse_flush+0x228/0x6a0 fs/fuse/file.c:499
3 locks held by syz.3.306/5501:
 #0: ffff0000c35f1768 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x114/0x16c fs/file.c:1040
 #1: ffff0000d7c4a460 (sb_writers#23){.+.+}-{0:0}, at: vfs_writev fs/read_write.c:933 [inline]
 #1: ffff0000d7c4a460 (sb_writers#23){.+.+}-{0:0}, at: do_writev+0x1cc/0x380 fs/read_write.c:977
 #2: ffff0000f5c70150 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:758 [inline]
 #2: ffff0000f5c70150 (&sb->s_type->i_mutex_key#28){+.+.}-{3:3}, at: fuse_fsync+0xf0/0x2b8 fs/fuse/file.c:567
1 lock held by syz-executor/5991:
 #0: ffff80001528cab8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #0: ffff80001528cab8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x3a8/0x6f0 kernel/rcu/tree_exp.h:962
2 locks held by kworker/0:13/7412:
 #0: ffff0000c0020938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x6b4/0x13a8 kernel/workqueue.c:2265
 #1: ffff800021b57c20 (key_gc_work){+.+.}-{0:0}, at: process_one_work+0x6f8/0x13a8 kernel/workqueue.c:2267

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


Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/06 03:32 linux-6.1.y 7e69c33e4858 4f67c4ae .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in fuse_set_nowrite
* Struck through repros no longer work on HEAD.