syzbot


INFO: task hung in exfat_lookup

Status: auto-obsoleted due to no activity on 2023/12/19 10:59
Subsystems: exfat
[Documentation on labels]
First crash: 575d, last: 575d
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in exfat_lookup (3) exfat C done done 7 104d 109d 0/28 auto-obsoleted due to no activity on 2025/04/13 03:04
upstream INFO: task hung in exfat_lookup (2) exfat 8 284d 468d 0/28 auto-obsoleted due to no activity on 2024/10/05 08:40

Sample crash report:
INFO: task syz-executor.0:11851 blocked for more than 143 seconds.
      Not tainted 6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:26864 pid:11851 ppid:5064   flags:0x00004006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5382 [inline]
 __schedule+0x196c/0x4af0 kernel/sched/core.c:6695
 schedule+0xc3/0x180 kernel/sched/core.c:6771
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6830
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6a3/0xd60 kernel/locking/mutex.c:747
 exfat_lookup+0x136/0x1870 fs/exfat/namei.c:709
 lookup_open fs/namei.c:3473 [inline]
 open_last_lookups fs/namei.c:3563 [inline]
 path_openat+0x11f1/0x3180 fs/namei.c:3793
 do_filp_open+0x234/0x490 fs/namei.c:3823
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1422
 do_sys_open fs/open.c:1437 [inline]
 __do_sys_open fs/open.c:1445 [inline]
 __se_sys_open fs/open.c:1441 [inline]
 __x64_sys_open+0x225/0x270 fs/open.c:1441
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7114a7cae9
RSP: 002b:00007f71157d80c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f7114b9c120 RCX: 00007f7114a7cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000040
RBP: 00007f7114ac847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007f7114b9c120 R15: 00007ffd859e4038
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/29:
 #0: ffffffff8d32c4a0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:303 [inline]
 #0: ffffffff8d32c4a0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:749 [inline]
 #0: ffffffff8d32c4a0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6613
4 locks held by kworker/u4:3/48:
 #0: ffff8880132fcd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2605 [inline]
 #0: ffff8880132fcd38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x825/0x1400 kernel/workqueue.c:2703
 #1: ffffc90000b8fd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2605 [inline]
 #1: ffffc90000b8fd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x825/0x1400 kernel/workqueue.c:2703
 #2: ffff88807a02a0e0 (&type->s_umount_key#106){++++}-{3:3}, at: super_trylock_shared+0x22/0xf0 fs/super.c:607
 #3: ffff88807a02c0e0 (&sbi->s_lock#2){+.+.}-{3:3}, at: exfat_write_inode+0x69/0x120 fs/exfat/inode.c:93
2 locks held by getty/4786:
 #0: ffff888025f6c0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc90002f062f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b1/0x1dc0 drivers/tty/n_tty.c:2206
1 lock held by syz-executor.5/5060:
5 locks held by syz-executor.0/11845:
2 locks held by syz-executor.0/11851:
 #0: ffff88823bda4cb0 (&sb->s_type->i_mutex_key#32){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:812 [inline]
 #0: ffff88823bda4cb0 (&sb->s_type->i_mutex_key#32){++++}-{3:3}, at: open_last_lookups fs/namei.c:3562 [inline]
 #0: ffff88823bda4cb0 (&sb->s_type->i_mutex_key#32){++++}-{3:3}, at: path_openat+0x7b3/0x3180 fs/namei.c:3793
 #1: ffff88807a02c0e0 (&sbi->s_lock#2){+.+.}-{3:3}, at: exfat_lookup+0x136/0x1870 fs/exfat/namei.c:709

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

NMI backtrace for cpu 0
CPU: 0 PID: 29 Comm: khungtaskd Not tainted 6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x498/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x310 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xfa9/0xff0 kernel/hung_task.c:379
 kthread+0x2d3/0x370 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5060 Comm: syz-executor.5 Not tainted 6.6.0-rc2-syzkaller-00018-g2cf0f7156238 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
RIP: 0010:unwind_next_frame+0x1bd/0x29e0 arch/x86/kernel/unwind_orc.c:494
Code: 30 42 80 3c 30 00 74 08 48 89 df e8 3d d2 aa 00 48 03 2b 48 8d 75 ff 31 ff e8 2f 6e 50 00 48 ff cd 4c 89 24 24 4c 89 7c 24 70 <4c> 89 6c 24 48 0f 84 41 01 00 00 48 c7 c3 00 00 00 81 48 89 ef 48
RSP: 0018:ffffc90003aaf6c8 EFLAGS: 00000287
RAX: 0000000000000000 RBX: ffffc90003aaf7e8 RCX: ffff888016723b80
RDX: ffffc90003aaf7d5 RSI: ffffffff8acca630 RDI: 0000000000000000
RBP: ffffffff8acca630 R08: ffffffff813da111 R09: ffffc90003aaf890
R10: 0000000000000003 R11: ffff888016723b80 R12: ffffc90003aaf7a0
R13: ffffc90003aaf7f0 R14: dffffc0000000000 R15: ffffffff8acca631
FS:  0000555556b6b480(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000c01ff64000 CR3: 000000002e825000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <NMI>
 </NMI>
 <TASK>
 arch_stack_walk+0x146/0x1a0 arch/x86/kernel/stacktrace.c:25
 stack_trace_save+0x117/0x1c0 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1800 [inline]
 slab_free_freelist_hook mm/slub.c:1826 [inline]
 slab_free mm/slub.c:3809 [inline]
 __kmem_cache_free+0x25f/0x3b0 mm/slub.c:3822
 tomoyo_path_number_perm+0x68d/0x870 security/tomoyo/file.c:736
 security_file_ioctl+0x71/0xa0 security/security.c:2647
 __do_sys_ioctl fs/ioctl.c:865 [inline]
 __se_sys_ioctl+0x47/0x170 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f20df67c84b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007fffd4ec6ed0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000000042e5 RCX: 00007f20df67c84b
RDX: 00007fffd4ec6f48 RSI: 0000000040086602 RDI: 0000000000000006
RBP: 00007fffd4ec6fe0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fffd4ec80d0
R13: 00007f20df6c73b9 R14: 0000555556b6b430 R15: 0000000000000006
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/09/20 10:54 upstream 2cf0f7156238 0b6a67ac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in exfat_lookup
* Struck through repros no longer work on HEAD.