syzbot


INFO: task hung in btrfs_sync_file (2)

Status: fixed on 2023/09/28 17:51
Subsystems: btrfs
[Documentation on labels]
Reported-by: syzbot+a694851c6ab28cbcfb9c@syzkaller.appspotmail.com
Fix commit: 745806fb4554 btrfs: do not ASSERT() on duplicated global roots
First crash: 456d, last: 389d
Cause bisection: failed (error log, bisect log)
  
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [btrfs?] INFO: task hung in btrfs_sync_file (2) 4 (5) 2023/06/13 14:44
Similar bugs (2)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in btrfs_sync_file (3) btrfs 1 157d 157d 0/27 auto-obsoleted due to no activity on 2024/04/15 09:26
upstream INFO: task hung in btrfs_sync_file btrfs C error 2 500d 500d 0/27 closed as invalid on 2023/02/08 16:28

Sample crash report:
INFO: task syz-executor274:6164 blocked for more than 143 seconds.
      Not tainted 6.4.0-rc2-next-20230515-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor274 state:D stack:24920 pid:6164  ppid:5041   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5343 [inline]
 __schedule+0x1d15/0x5790 kernel/sched/core.c:6669
 schedule+0xde/0x1a0 kernel/sched/core.c:6745
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6804
 rwsem_down_write_slowpath+0x3e2/0x1220 kernel/locking/rwsem.c:1178
 __down_write_common kernel/locking/rwsem.c:1306 [inline]
 __down_write kernel/locking/rwsem.c:1315 [inline]
 down_write+0x1d2/0x200 kernel/locking/rwsem.c:1574
 inode_lock include/linux/fs.h:775 [inline]
 btrfs_inode_lock+0x7e/0xf0 fs/btrfs/inode.c:377
 btrfs_sync_file+0x455/0x12d0 fs/btrfs/file.c:1808
 vfs_fsync_range+0x13e/0x230 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2469 [inline]
 btrfs_do_write_iter+0x520/0x1210 fs/btrfs/file.c:1680
 call_write_iter include/linux/fs.h:1868 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x945/0xd50 fs/read_write.c:584
 ksys_write+0x12b/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0de39026c9
RSP: 002b:00007f0de38a5208 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f0de3984788 RCX: 00007f0de39026c9
RDX: 0000000000000128 RSI: 0000000020004400 RDI: 0000000000000006
RBP: 00007f0de3984780 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0de398478c
R13: 00007fffb0c5635f R14: 00007f0de38a5300 R15: 0000000000022000
 </TASK>
INFO: task syz-executor274:6181 blocked for more than 143 seconds.
      Not tainted 6.4.0-rc2-next-20230515-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor274 state:D stack:26416 pid:6181  ppid:5041   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5343 [inline]
 __schedule+0x1d15/0x5790 kernel/sched/core.c:6669
 schedule+0xde/0x1a0 kernel/sched/core.c:6745
 wait_on_state fs/btrfs/extent-io-tree.c:707 [inline]
 wait_extent_bit+0x56e/0x670 fs/btrfs/extent-io-tree.c:751
 lock_extent+0x120/0x1c0 fs/btrfs/extent-io-tree.c:1742
 btrfs_page_mkwrite+0x652/0x11a0 fs/btrfs/inode.c:8336
 do_page_mkwrite+0x1a1/0x690 mm/memory.c:2934
 wp_page_shared mm/memory.c:3283 [inline]
 do_wp_page+0x356/0x34e0 mm/memory.c:3365
 handle_pte_fault mm/memory.c:4967 [inline]
 __handle_mm_fault+0x1635/0x4170 mm/memory.c:5092
 handle_mm_fault+0x2af/0x9f0 mm/memory.c:5246
 do_user_addr_fault+0x51a/0x1210 arch/x86/mm/fault.c:1440
 handle_page_fault arch/x86/mm/fault.c:1534 [inline]
 exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:rep_movs_alternative+0x33/0xb0 arch/x86/lib/copy_user_64.S:56
Code: 46 83 f9 08 73 21 85 c9 74 0f 8a 06 88 07 48 ff c7 48 ff c6 48 ff c9 75 f1 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 8b 06 <48> 89 07 48 83 c6 08 48 83 c7 08 83 e9 08 74 df 83 f9 08 73 e8 eb
RSP: 0018:ffffc9000becf728 EFLAGS: 00050206
RAX: 0000000000000000 RBX: 0000000000000038 RCX: 0000000000000038
RDX: fffff520017d9efb RSI: ffffc9000becf7a0 RDI: 0000000020000120
RBP: 0000000020000120 R08: 0000000000000000 R09: fffff520017d9efa
R10: ffffc9000becf7d7 R11: 0000000000000001 R12: ffffc9000becf7a0
R13: 0000000020000158 R14: 0000000000000000 R15: ffffc9000becf7a0
 copy_user_generic arch/x86/include/asm/uaccess_64.h:112 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:133 [inline]
 _copy_to_user lib/usercopy.c:41 [inline]
 _copy_to_user+0xab/0xc0 lib/usercopy.c:34
 copy_to_user include/linux/uaccess.h:191 [inline]
 fiemap_fill_next_extent+0x217/0x370 fs/ioctl.c:144
 emit_fiemap_extent+0x18e/0x380 fs/btrfs/extent_io.c:2616
 fiemap_process_hole+0x516/0x610 fs/btrfs/extent_io.c:2874
 extent_fiemap+0x123b/0x1950 fs/btrfs/extent_io.c:3089
 btrfs_fiemap+0xe9/0x170 fs/btrfs/inode.c:8008
 ioctl_fiemap fs/ioctl.c:219 [inline]
 do_vfs_ioctl+0x466/0x1670 fs/ioctl.c:810
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x10c/0x210 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0de39026c9
RSP: 002b:00007f0ddc484208 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f0de3984798 RCX: 00007f0de39026c9
RDX: 0000000020000100 RSI: 00000000c020660b RDI: 0000000000000005
RBP: 00007f0de3984790 R08: 00007f0ddc484700 R09: 0000000000000000
R10: 00007f0ddc484700 R11: 0000000000000246 R12: 00007f0de398479c
R13: 00007fffb0c5635f R14: 00007f0ddc484300 R15: 0000000000022000
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/13:
 #0: ffffffff8c798530 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:522
1 lock held by rcu_tasks_trace/14:
 #0: ffffffff8c798230 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x31/0xd80 kernel/rcu/tasks.h:522
1 lock held by khungtaskd/28:
 #0: ffffffff8c799140 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x390 kernel/locking/lockdep.c:6559
2 locks held by getty/4759:
 #0: ffff888028dba098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x26/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900015902f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0xef4/0x13e0 drivers/tty/n_tty.c:2176
3 locks held by syz-executor274/6164:
 #0: ffff888027b554e8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe7/0x100 fs/file.c:1047
 #1: ffff88807cee8460 (sb_writers#10){.+.+}-{0:0}, at: ksys_write+0x12b/0x250 fs/read_write.c:637
 #2: ffff888075278590 (&sb->s_type->i_mutex_key#15){++++}-{3:3}, at: inode_lock include/linux/fs.h:775 [inline]
 #2: ffff888075278590 (&sb->s_type->i_mutex_key#15){++++}-{3:3}, at: btrfs_inode_lock+0x7e/0xf0 fs/btrfs/inode.c:377
4 locks held by syz-executor274/6181:
 #0: ffff888075278590 (&sb->s_type->i_mutex_key#15){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:785 [inline]
 #0: ffff888075278590 (&sb->s_type->i_mutex_key#15){++++}-{3:3}, at: btrfs_inode_lock+0xd8/0xf0 fs/btrfs/inode.c:369
 #1: ffff88807f081368 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:161 [inline]
 #1: ffff88807f081368 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x448/0x1210 arch/x86/mm/fault.c:1381
 #2: ffff88807cee8558 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x1a1/0x690 mm/memory.c:2934
 #3: ffff888075278418 (&ei->i_mmap_lock){++++}-{3:3}, at: btrfs_page_mkwrite+0x6eb/0x11a0 fs/btrfs/inode.c:8325

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.4.0-rc2-next-20230515-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x29c/0x350 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x2a4/0x300 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
 watchdog+0xe16/0x1090 kernel/hung_task.c:379
 kthread+0x344/0x440 kernel/kthread.c:379
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
 </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+0x40/0x50 drivers/acpi/processor_idle.c:112

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2023/05/29 00:55 linux-next 715abedee4cd cf184559 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci-upstream-linux-next-kasan-gce-root INFO: task hung in btrfs_sync_file
2023/04/24 04:23 upstream 457391b03803 2b32bd34 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in btrfs_sync_file
2023/04/19 12:19 upstream af67688dca57 94b4184e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in btrfs_sync_file
2023/03/29 10:19 upstream fcd476ea6a88 f325deb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in btrfs_sync_file
2023/03/23 10:30 upstream fff5a5e7f528 f94b4a29 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs INFO: task hung in btrfs_sync_file
* Struck through repros no longer work on HEAD.