syzbot


INFO: task hung in extent_writepages (2)

Status: upstream: reported on 2024/10/31 22:43
Reported-by: syzbot+c898504f8dceab6aadd0@syzkaller.appspotmail.com
First crash: 20d, last: 20d
Similar bugs (4)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in extent_writepages 3 171d 197d 0/3 auto-obsoleted due to no activity on 2024/09/11 18:05
upstream INFO: task hung in extent_writepages btrfs C inconclusive done 30 288d 477d 0/28 auto-obsoleted due to no activity on 2024/05/17 02:53
linux-5.15 INFO: task hung in extent_writepages 1 577d 577d 0/3 auto-obsoleted due to no activity on 2023/08/22 08:46
linux-5.15 INFO: task hung in extent_writepages (2) 1 195d 195d 0/3 auto-obsoleted due to no activity on 2024/08/18 00:52

Sample crash report:
INFO: task kworker/u4:16:4950 blocked for more than 143 seconds.
      Not tainted 6.1.114-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:16   state:D stack:21944 pid:4950  ppid:2      flags:0x00004000
Workqueue: writeback wb_workfn (flush-btrfs-6)
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 io_schedule+0x88/0x100 kernel/sched/core.c:8786
 folio_wait_bit_common+0x878/0x1290 mm/filemap.c:1324
 extent_write_cache_pages fs/btrfs/extent_io.c:3171 [inline]
 extent_writepages+0x8de/0x17a0 fs/btrfs/extent_io.c:3313
 do_writepages+0x3a2/0x670 mm/page-writeback.c:2491
 __writeback_single_inode+0x15d/0x11e0 fs/fs-writeback.c:1612
 writeback_sb_inodes+0xc2b/0x1b20 fs/fs-writeback.c:1903
 __writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:1974
 wb_writeback+0x4b1/0xe10 fs/fs-writeback.c:2079
 wb_check_background_flush fs/fs-writeback.c:2145 [inline]
 wb_do_writeback fs/fs-writeback.c:2233 [inline]
 wb_workfn+0xc9e/0x1020 fs/fs-writeback.c:2260
 process_one_work+0x8a9/0x11d0 kernel/workqueue.c:2292
 worker_thread+0xa47/0x1200 kernel/workqueue.c:2439
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
INFO: task syz.6.307:5987 blocked for more than 143 seconds.
      Not tainted 6.1.114-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.307       state:D stack:23472 pid:5987  ppid:4678   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 wait_on_state fs/btrfs/extent-io-tree.c:709 [inline]
 wait_extent_bit+0x423/0x570 fs/btrfs/extent-io-tree.c:742
 lock_extent+0x17a/0x200 fs/btrfs/extent-io-tree.c:1657
 btrfs_page_mkwrite+0x550/0xc90 fs/btrfs/inode.c:8610
 do_page_mkwrite+0x1a1/0x5f0 mm/memory.c:3009
 wp_page_shared+0x164/0x380 mm/memory.c:3358
 handle_pte_fault mm/memory.c:5047 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x2525/0x5340 mm/memory.c:5292
 do_user_addr_fault arch/x86/mm/fault.c:1340 [inline]
 handle_page_fault arch/x86/mm/fault.c:1431 [inline]
 exc_page_fault+0x26f/0x620 arch/x86/mm/fault.c:1487
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
RIP: 0010:copy_user_short_string+0xd/0x40 arch/x86/lib/copy_user_64.S:233
Code: 74 0a 89 d1 f3 a4 89 c8 0f 01 ca c3 89 d0 0f 01 ca c3 01 ca eb e7 0f 1f 80 00 00 00 00 89 d1 83 e2 07 c1 e9 03 74 12 4c 8b 06 <4c> 89 07 48 8d 76 08 48 8d 7f 08 ff c9 75 ee 21 d2 74 10 89 d1 8a
RSP: 0018:ffffc900045ef3b0 EFLAGS: 00050202
RAX: ffffffff8439b501 RBX: 00007fffffffefc8 RCX: 0000000000000007
RDX: 0000000000000000 RSI: ffffc900045ef460 RDI: 00000000200004e0
RBP: ffffc900045ef510 R08: 0000000000000000 R09: fffff520008bde93
R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000038
R13: ffffc900045ef460 R14: 00000000200004e0 R15: ffffc900045ef460
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_to_user arch/x86/include/asm/uaccess_64.h:58 [inline]
 _copy_to_user+0xe9/0x130 lib/usercopy.c:41
 copy_to_user include/linux/uaccess.h:169 [inline]
 fiemap_fill_next_extent+0x231/0x410 fs/ioctl.c:144
 emit_fiemap_extent fs/btrfs/extent_io.c:3561 [inline]
 fiemap_process_hole+0x107e/0x1290 fs/btrfs/extent_io.c:3821
 extent_fiemap+0xef7/0x1ff0
 btrfs_fiemap+0x174/0x1e0 fs/btrfs/inode.c:8282
 ioctl_fiemap fs/ioctl.c:219 [inline]
 do_vfs_ioctl+0x18e9/0x2a90 fs/ioctl.c:810
 __do_sys_ioctl fs/ioctl.c:868 [inline]
 __se_sys_ioctl+0x81/0x160 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f059e97e719
RSP: 002b:00007f059f6b3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f059eb35f80 RCX: 00007f059e97e719
RDX: 00000000200004c0 RSI: 00000000c020660b RDI: 0000000000000004
RBP: 00007f059e9f132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f059eb35f80 R15: 00007ffc42d6d7e8
 </TASK>
INFO: task syz.6.307:6033 blocked for more than 145 seconds.
      Not tainted 6.1.114-syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.307       state:D stack:23344 pid:6033  ppid:4678   flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5241 [inline]
 __schedule+0x143f/0x4570 kernel/sched/core.c:6558
 schedule+0xbf/0x180 kernel/sched/core.c:6634
 io_schedule+0x88/0x100 kernel/sched/core.c:8786
 folio_wait_bit_common+0x878/0x1290 mm/filemap.c:1324
 extent_write_cache_pages fs/btrfs/extent_io.c:3171 [inline]
 extent_writepages+0x8de/0x17a0 fs/btrfs/extent_io.c:3313
 do_writepages+0x3a2/0x670 mm/page-writeback.c:2491
 filemap_fdatawrite_wbc+0x121/0x180 mm/filemap.c:388
 __filemap_fdatawrite_range mm/filemap.c:421 [inline]
 filemap_fdatawrite_range+0x16a/0x1e0 mm/filemap.c:439
 btrfs_fdatawrite_range fs/btrfs/file.c:3877 [inline]
 start_ordered_ops+0xe6/0x210 fs/btrfs/file.c:1744
 btrfs_sync_file+0x48f/0x1300 fs/btrfs/file.c:1827
 generic_write_sync include/linux/fs.h:2962 [inline]
 btrfs_do_write_iter+0xad2/0x1360 fs/btrfs/file.c:1693
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x857/0xbc0 fs/read_write.c:584
 ksys_write+0x19c/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f059e97e719
RSP: 002b:00007f059f692038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f059eb36058 RCX: 00007f059e97e719
RDX: 0000000000000020 RSI: 0000000020000280 RDI: 0000000000000005
RBP: 00007f059e9f132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f059eb36058 R15: 00007ffc42d6d7e8
 </TASK>

Showing all locks held in the system:
1 lock held by rcu_tasks_kthre/12:
 #0: ffffffff8d32b1d0 (rcu_tasks.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by rcu_tasks_trace/13:
 #0: ffffffff8d32b9d0 (rcu_tasks_trace.tasks_gp_mutex){+.+.}-{3:3}, at: rcu_tasks_one_gp+0x29/0xe30 kernel/rcu/tasks.h:517
1 lock held by khungtaskd/28:
 #0: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:350 [inline]
 #0: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:791 [inline]
 #0: ffffffff8d32b000 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x51/0x290 kernel/locking/lockdep.c:6510
6 locks held by kworker/u4:2/33:
 #0: ffff888017e16938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc90000aa7d20 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #2: ffffffff8e4eec50 (pernet_ops_rwsem){++++}-{3:3}, at: cleanup_net+0xf1/0xb60 net/core/net_namespace.c:566
 #3: ffff88806218d2f8 (&devlink->lock_key#17){+.+.}-{3:3}, at: devlink_pernet_pre_exit+0x132/0x2f0 net/devlink/leftover.c:12500
 #4: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: nsim_destroy+0x3a/0x140 drivers/net/netdevsim/netdev.c:381
 #5: ffffffff8d3305f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: exp_funnel_lock kernel/rcu/tree_exp.h:291 [inline]
 #5: ffffffff8d3305f8 (rcu_state.exp_mutex){+.+.}-{3:3}, at: synchronize_rcu_expedited+0x4f0/0x930 kernel/rcu/tree_exp.h:962
3 locks held by kworker/0:3/1168:
 #0: ffff88814ce87938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc90004e47d20 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #2: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xcc/0x16b0 net/ipv6/addrconf.c:4115
1 lock held by dhcpcd/3917:
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
2 locks held by getty/4013:
 #0: ffff88807e6c0098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:244
 #1: ffffc900032462f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6a7/0x1db0 drivers/tty/n_tty.c:2198
3 locks held by kworker/1:4/4295:
 #0: ffff88814ce87938 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc9000441fd20 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #2: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: addrconf_dad_work+0xcc/0x16b0 net/ipv6/addrconf.c:4115
2 locks held by kworker/0:5/4298:
 #0: ffff888017c72138 ((wq_completion)rcu_gp){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc9000444fd20 ((work_completion)(&rew->rew_work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
3 locks held by kworker/u4:12/4375:
 #0: ffff888017c79138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc9000477fd20 ((linkwatch_work).work){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #2: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: linkwatch_event+0xa/0x50 net/core/link_watch.c:263
3 locks held by kworker/u4:16/4950:
 #0: ffff888141e7d938 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #1: ffffc90003bbfd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7a9/0x11d0 kernel/workqueue.c:2267
 #2: ffff88805962a0e0 (&type->s_umount_key#78){++++}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:415
4 locks held by syz.6.307/5987:
 #0: ffff8880593da2c0 (&sb->s_type->i_mutex_key#27){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:768 [inline]
 #0: ffff8880593da2c0 (&sb->s_type->i_mutex_key#27){++++}-{3:3}, at: btrfs_inode_lock+0x5c/0xd0 fs/btrfs/inode.c:147
 #1: ffff88807cd02e58 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #1: ffff88807cd02e58 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5320 [inline]
 #1: ffff88807cd02e58 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x2e/0x2e0 mm/memory.c:5382
 #2: ffff88805962a558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x1a1/0x5f0 mm/memory.c:3009
 #3: ffff8880593da148 (&ei->i_mmap_lock){++++}-{3:3}, at: btrfs_page_mkwrite+0x421/0xc90 fs/btrfs/inode.c:8599
2 locks held by syz.6.307/6033:
 #0: ffff888024ecefe8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2ba/0x360 fs/file.c:1031
 #1: ffff88805962a460 (sb_writers#22){.+.+}-{0:0}, at: vfs_write+0x269/0xbc0 fs/read_write.c:580
7 locks held by syz-executor/6779:
 #0: ffff88807e326460 (sb_writers#8){.+.+}-{0:0}, at: vfs_write+0x269/0xbc0 fs/read_write.c:580
 #1: ffff8880246cd488 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x1e7/0x4f0 fs/kernfs/file.c:325
 #2: ffff888144f8aa00 (kn->active#51){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x20b/0x4f0 fs/kernfs/file.c:326
 #3: ffffffff8de24168 (nsim_bus_dev_list_lock){+.+.}-{3:3}, at: new_device_store+0x1ad/0x800 drivers/net/netdevsim/bus.c:160
 #4: ffff88807db6b0e8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:837 [inline]
 #4: ffff88807db6b0e8 (&dev->mutex){....}-{3:3}, at: __device_attach+0x8a/0x570 drivers/base/dd.c:990
 #5: ffff88807db692f8 (&devlink->lock_key#24){+.+.}-{3:3}, at: nsim_drv_probe+0xc9/0xb20 drivers/net/netdevsim/dev.c:1539
 #6: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: nsim_init_netdevsim drivers/net/netdevsim/netdev.c:310 [inline]
 #6: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: nsim_create+0x30c/0x3f0 drivers/net/netdevsim/netdev.c:365
1 lock held by syz-executor/6974:
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
1 lock held by syz-executor/7055:
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
1 lock held by syz-executor/7149:
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147
1 lock held by syz-executor/7241:
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock net/core/rtnetlink.c:74 [inline]
 #0: ffffffff8e4fafa8 (rtnl_mutex){+.+.}-{3:3}, at: rtnetlink_rcv_msg+0x7c1/0xff0 net/core/rtnetlink.c:6147

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

NMI backtrace for cpu 1
CPU: 1 PID: 28 Comm: khungtaskd Not tainted 6.1.114-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 nmi_cpu_backtrace+0x4e1/0x560 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x1ae/0x3f0 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:220 [inline]
 watchdog+0xf88/0xfd0 kernel/hung_task.c:377
 kthread+0x28d/0x320 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </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:51 [inline]
NMI backtrace for cpu 0 skipped: idling at arch_safe_halt arch/x86/include/asm/irqflags.h:89 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_safe_halt drivers/acpi/processor_idle.c:111 [inline]
NMI backtrace for cpu 0 skipped: idling at acpi_idle_do_entry+0x10f/0x340 drivers/acpi/processor_idle.c:567

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/10/31 22:42 linux-6.1.y 7ec6f9fa3d97 96eb609f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan INFO: task hung in extent_writepages
* Struck through repros no longer work on HEAD.