syzbot


INFO: task hung in ext4_file_write_iter (5)

Status: auto-obsoleted due to no activity on 2024/06/06 13:22
Subsystems: ext4
[Documentation on labels]
First crash: 409d, last: 409d
Similar bugs (6)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-44 INFO: task hung in ext4_file_write_iter 1 2102d 2102d 0/2 auto-closed as invalid on 2019/12/17 11:11
android-414 INFO: task hung in ext4_file_write_iter 6 2237d 2230d 0/1 auto-closed as invalid on 2019/10/03 05:16
upstream INFO: task hung in ext4_file_write_iter ext4 4 2299d 2571d 0/28 auto-closed as invalid on 2019/08/02 09:02
upstream INFO: task hung in ext4_file_write_iter (4) ext4 2 772d 784d 0/28 auto-obsoleted due to no activity on 2023/07/09 14:32
upstream INFO: task hung in ext4_file_write_iter (3) ext4 1 884d 884d 0/28 auto-obsoleted due to no activity on 2023/03/28 01:11
upstream INFO: task hung in ext4_file_write_iter (2) ext4 1 1617d 1617d 0/28 auto-closed as invalid on 2021/03/16 20:08

Sample crash report:
INFO: task syz-executor.0:20224 blocked for more than 143 seconds.
      Not tainted 6.9.0-rc2-next-20240405-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:28368 pid:20224 tgid:20220 ppid:17004  flags:0x00000006
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5409 [inline]
 __schedule+0x17e8/0x4a50 kernel/sched/core.c:6746
 __schedule_loop kernel/sched/core.c:6823 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6838
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:6895
 rwsem_down_write_slowpath+0xeeb/0x13b0 kernel/locking/rwsem.c:1178
 __down_write_common+0x1af/0x200 kernel/locking/rwsem.c:1306
 inode_lock include/linux/fs.h:786 [inline]
 ext4_dio_write_iter fs/ext4/file.c:530 [inline]
 ext4_file_write_iter+0x388/0x1a10 fs/ext4/file.c:696
 call_write_iter include/linux/fs.h:2106 [inline]
 new_sync_write fs/read_write.c:497 [inline]
 vfs_write+0xa72/0xc90 fs/read_write.c:590
 ksys_write+0x1a0/0x2c0 fs/read_write.c:643
 do_syscall_64+0xfb/0x240
 entry_SYSCALL_64_after_hwframe+0x72/0x7a
RIP: 0033:0x7fd55de7de69
RSP: 002b:00007fd55ebad0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fd55dfac050 RCX: 00007fd55de7de69
RDX: 000000000000f000 RSI: 0000000020000200 RDI: 0000000000000004
RBP: 00007fd55deca47a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000006e R14: 00007fd55dfac050 R15: 00007ffeb4a7d198
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/7:
 #0: ffff8880b943e618 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0xb0/0x140 kernel/sched/core.c:567
 #1: ffff8880b9428948 (&per_cpu_ptr(group->pcpu, cpu)->seq){-.-.}-{0:0}, at: psi_task_switch+0x441/0x770 kernel/sched/psi.c:988
1 lock held by khungtaskd/29:
 #0: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:329 [inline]
 #0: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:841 [inline]
 #0: ffffffff8e334ea0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x2a0 kernel/locking/lockdep.c:6614
2 locks held by getty/4832:
 #0: ffff88802ab740a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
 #1: ffffc900031432f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6b5/0x1e10 drivers/tty/n_tty.c:2201
3 locks held by syz-fuzzer/5185:
 #0: ffff88802f95e420 (sb_writers#4){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:409
 #1: ffff88805bab6800 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:821 [inline]
 #1: ffff88805bab6800 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: do_unlinkat+0x26a/0x830 fs/namei.c:4386
 #2: ffff8880530dc000 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:786 [inline]
 #2: ffff8880530dc000 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: vfs_unlink+0xe4/0x650 fs/namei.c:4324
2 locks held by kworker/0:5/5146:
5 locks held by syz-executor.0/20223:
3 locks held by syz-executor.0/20224:
 #0: ffff88804ceb3c48 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x259/0x320 fs/file.c:1191
 #1: ffff88802f95e420 (sb_writers#4){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:2851 [inline]
 #1: ffff88802f95e420 (sb_writers#4){.+.+}-{0:0}, at: vfs_write+0x227/0xc90 fs/read_write.c:586
 #2: ffff8880530dc000 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock include/linux/fs.h:786 [inline]
 #2: ffff8880530dc000 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_dio_write_iter fs/ext4/file.c:530 [inline]
 #2: ffff8880530dc000 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_file_write_iter+0x388/0x1a10 fs/ext4/file.c:696
2 locks held by syz-executor.0/20230:
2 locks held by syz-executor.0/20232:
1 lock held by syz-executor.0/20238:

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

NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.9.0-rc2-next-20240405-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 nmi_cpu_backtrace+0x49c/0x4d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x198/0x320 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:223 [inline]
 watchdog+0xfde/0x1020 kernel/hung_task.c:380
 kthread+0x2f0/0x390 kernel/kthread.c:388
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0 skipped: idling at native_safe_halt arch/x86/include/asm/irqflags.h:48 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:86 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt+0x21/0x30 drivers/acpi/processor_idle.c:112

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/04/07 13:19 linux-next 8568bb2ccc27 ca620dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root INFO: task hung in ext4_file_write_iter
* Struck through repros no longer work on HEAD.