syzbot


INFO: task hung in exfat_write_inode

Status: auto-obsoleted due to no activity on 2024/01/23 18:02
Reported-by: syzbot+25f77c2f928dab8c57a1@syzkaller.appspotmail.com
First crash: 347d, last: 283d
Similar bugs (3)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in exfat_write_inode exfat C done error 3064 1d14h 580d 0/27 upstream: reported C repro on 2022/12/22 18:53
linux-5.15 INFO: task hung in exfat_write_inode origin:upstream C 12 25d 102d 0/3 upstream: reported C repro on 2024/04/13 19:03
linux-6.1 INFO: task hung in exfat_write_inode (2) origin:upstream C 155 12h42m 100d 0/3 upstream: reported C repro on 2024/04/15 01:39

Sample crash report:
INFO: task kworker/u4:6:12956 blocked for more than 145 seconds.
      Not tainted 6.1.58-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:6    state:D stack:0     pid:12956 ppid:2      flags:0x00000008
Workqueue: writeback wb_workfn (flush-7:0)
Call trace:
 __switch_to+0x320/0x754 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0xee4/0x1c98 kernel/sched/core.c:6554
 schedule+0xc4/0x170 kernel/sched/core.c:6630
 schedule_preempt_disabled+0x18/0x2c kernel/sched/core.c:6689
 __mutex_lock_common+0xbd8/0x21a0 kernel/locking/mutex.c:679
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
 exfat_write_inode+0x70/0x114 fs/exfat/inode.c:94
 write_inode fs/fs-writeback.c:1443 [inline]
 __writeback_single_inode+0x614/0x1770 fs/fs-writeback.c:1655
 writeback_sb_inodes+0x978/0x16c0 fs/fs-writeback.c:1881
 __writeback_inodes_wb+0x110/0x39c fs/fs-writeback.c:1952
 wb_writeback+0x428/0x1130 fs/fs-writeback.c:2057
 wb_check_background_flush fs/fs-writeback.c:2123 [inline]
 wb_do_writeback fs/fs-writeback.c:2211 [inline]
 wb_workfn+0xc98/0x1034 fs/fs-writeback.c:2238
 process_one_work+0x7ac/0x1404 kernel/workqueue.c:2292
 worker_thread+0x8e4/0xfec kernel/workqueue.c:2439
 kthread+0x250/0x2d8 kernel/kthread.c:376
 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:864
INFO: task syz-executor.0:19449 blocked for more than 145 seconds.
      Not tainted 6.1.58-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:0     pid:19449 ppid:4241   flags:0x00000005
Call trace:
 __switch_to+0x320/0x754 arch/arm64/kernel/process.c:553
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0xee4/0x1c98 kernel/sched/core.c:6554
 schedule+0xc4/0x170 kernel/sched/core.c:6630
 rwsem_down_write_slowpath+0xc80/0x156c 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:756 [inline]
 do_truncate+0x1ac/0x28c fs/open.c:63
 handle_truncate fs/namei.c:3216 [inline]
 do_open fs/namei.c:3561 [inline]
 path_openat+0x1fa0/0x2548 fs/namei.c:3714
 do_filp_open+0x1bc/0x3cc fs/namei.c:3741
 do_sys_openat2+0x128/0x3d8 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_openat fs/open.c:1350 [inline]
 __se_sys_openat fs/open.c:1345 [inline]
 __arm64_sys_openat+0x1f0/0x240 fs/open.c:1345
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x168 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: ffff800015a84d70 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x44/0xcf4 kernel/rcu/tasks.h:516
1 lock held by rcu_tasks_trace/13:
 #0: ffff800015a85570 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x44/0xcf4 kernel/rcu/tasks.h:516
1 lock held by khungtaskd/28:
 #0: ffff800015a84ba0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0xc/0x44 include/linux/rcupdate.h:305
2 locks held by getty/3982:
 #0: ffff0000cfabc098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x4c drivers/tty/tty_ldsem.c:340
 #1: ffff80001bd202f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x414/0x1214 drivers/tty/n_tty.c:2188
4 locks held by syz-executor.1/4256:
2 locks held by kworker/u4:8/4618:
4 locks held by kworker/u4:6/12956:
 #0: ffff0000c2e35938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x664/0x1404 kernel/workqueue.c:2265
 #1: ffff80001f687c20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x6a8/0x1404 kernel/workqueue.c:2267
 #2: ffff0001004e40e0 (&type->s_umount_key#104){.+.+}-{3:3}, at: trylock_super+0x28/0xf8 fs/super.c:415
 #3: ffff0000dab960e0 (&sbi->s_lock#2){+.+.}-{3:3}, at: exfat_write_inode+0x70/0x114 fs/exfat/inode.c:94
4 locks held by kworker/u4:0/18633:
4 locks held by syz-executor.0/19426:
2 locks held by syz-executor.0/19449:
 #0: ffff0001004e4460 (sb_writers#27){.+.+}-{0:0}, at: mnt_want_write+0x44/0x9c fs/namespace.c:393
 #1: ffff0001086702b0 (&sb->s_type->i_mutex_key#32){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
 #1: ffff0001086702b0 (&sb->s_type->i_mutex_key#32){+.+.}-{3:3}, at: do_truncate+0x1ac/0x28c fs/open.c:63

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Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/10/15 18:01 linux-6.1.y adc4d740ad9e f757a323 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in exfat_write_inode
2023/09/18 03:05 linux-6.1.y 09045dae0d90 0b6a67ac .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 INFO: task hung in exfat_write_inode
2023/08/12 04:02 linux-6.1.y 1321ab403b38 39990d51 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in exfat_write_inode
* Struck through repros no longer work on HEAD.