syzbot

INFO: task kworker/u4:2:154 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D stack:24272 pid:  154 ppid:     2 flags:0x00004000
Workqueue: btrfs-endio-write btrfs_work_helper
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 wait_on_state fs/btrfs/extent_io.c:868 [inline]
 wait_extent_bit+0x3b0/0x4e0 fs/btrfs/extent_io.c:906
 lock_extent_bits+0x85/0x110 fs/btrfs/extent_io.c:1469
 btrfs_finish_ordered_io+0x6af/0x1b20 fs/btrfs/inode.c:3108
 btrfs_work_helper+0x357/0xba0 fs/btrfs/async-thread.c:325
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task syz.0.17:4339 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.17        state:D stack:23152 pid: 4339 ppid:  4323 flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11c3/0x4350 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 wait_on_state fs/btrfs/extent_io.c:868 [inline]
 wait_extent_bit+0x3b0/0x4e0 fs/btrfs/extent_io.c:906
 lock_extent_bits+0x85/0x110 fs/btrfs/extent_io.c:1469
 btrfs_page_mkwrite+0x5b8/0xc90 fs/btrfs/inode.c:8978
 do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
 wp_page_shared+0x163/0x6c0 mm/memory.c:3259
 handle_pte_fault mm/memory.c:4668 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x1fbd/0x4440 mm/memory.c:4883
 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
 handle_page_fault arch/x86/mm/fault.c:1443 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
RIP: 0010:copy_user_generic_unrolled+0x89/0xc0 arch/x86/lib/copy_user_64.S:92
Code: 38 4c 89 47 20 4c 89 4f 28 4c 89 57 30 4c 89 5f 38 48 8d 76 40 48 8d 7f 40 ff c9 75 b6 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:ffffc900022d76a0 EFLAGS: 00050202
RAX: ffffffff83e2d101 RBX: 0000000000000038 RCX: 0000000000000007
RDX: 0000000000000000 RSI: ffffc900022d7740 RDI: 00002000000001e0
RBP: 0000000000000000 R08: 0000000000000000 R09: 1ffff9200045aeee
R10: dffffc0000000000 R11: fffff5200045aeef R12: 00007ffffffff000
R13: 0000200000000218 R14: ffffc900022d7740 R15: 00002000000001e0
 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+0xf0/0x130 lib/usercopy.c:40
 copy_to_user include/linux/uaccess.h:200 [inline]
 fiemap_fill_next_extent+0x1ba/0x380 fs/ioctl.c:144
 emit_fiemap_extent fs/btrfs/extent_io.c:5467 [inline]
 extent_fiemap+0x1264/0x1650 fs/btrfs/extent_io.c:5694
 btrfs_fiemap+0xc0/0x110 fs/btrfs/inode.c:8601
 ioctl_fiemap fs/ioctl.c:219 [inline]
 do_vfs_ioctl+0x1543/0x1f40 fs/ioctl.c:814
 __do_sys_ioctl fs/ioctl.c:872 [inline]
 __se_sys_ioctl+0x83/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f809ef1ce59
RSP: 002b:00007ffffaf75f08 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f809f195fa0 RCX: 00007f809ef1ce59
RDX: 00002000000001c0 RSI: 00000000c020660b RDI: 0000000000000006
RBP: 00007f809efb2e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f809f195fac R14: 00007f809f195fa0 R15: 00007f809f195fa0
 </TASK>

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffffffff8c31ef20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:2/154:
 #0: ffff88807b813138 ((wq_completion)btrfs-endio-write){+.+.}-{0:0}, at: process_one_work+0x75c/0xff0 kernel/workqueue.c:-1
 #1: ffffc90001fd7d00 ((work_completion)(&work->normal_work)){+.+.}-{0:0}, at: process_one_work+0x79e/0xff0 kernel/workqueue.c:2285
2 locks held by getty/3945:
 #0: ffff88814d09f098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc900021ce2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x594/0x1a50 drivers/tty/n_tty.c:2158
4 locks held by syz.0.17/4339:
 #0: ffff8880683e99b0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:797 [inline]
 #0: ffff8880683e99b0 (&sb->s_type->i_mutex_key#21){++++}-{3:3}, at: btrfs_inode_lock+0x61/0xe0 fs/btrfs/inode.c:116
 #1: ffff88807baa1628 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
 #1: ffff88807baa1628 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2bb/0xc90 arch/x86/mm/fault.c:1296
 #2: ffff88807cb34558 (sb_pagefaults#2){.+.+}-{0:0}, at: do_page_mkwrite+0x168/0x3c0 mm/memory.c:2922
 #3: ffff8880683e9838 (&ei->i_mmap_lock){.+.+}-{3:3}, at: btrfs_page_mkwrite+0x45b/0xc90 fs/btrfs/inode.c:8967
2 locks held by udevd/4365:
 #0: ffff8880201f1d18 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xf1/0x780 block/bdev.c:915
 #1: ffff8881473b2468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xb50 drivers/block/loop.c:1366
2 locks held by syz.1.489/4859:

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

NMI backtrace for cpu 0
CPU: 0 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x3a2/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe1b/0xe60 kernel/hung_task.c:369
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 4365 Comm: udevd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:trace_hardirqs_on+0x1/0x80 kernel/trace/trace_preemptirq.c:41
Code: e9 94 fe ff ff e8 3f d8 f9 ff 0f 0b e9 39 ff ff ff e8 33 d8 f9 ff e8 b6 62 81 ff e9 79 fe ff ff 66 0f 1f 84 00 00 00 00 00 53 <e8> 1a d8 f9 ff 65 8b 1d 6b 18 84 7e 31 ff 89 de e8 6a db f9 ff 85
RSP: 0018:ffffc9000339f630 EFLAGS: 00000006
RAX: 00000000001d961c RBX: 1ffff92000673ee5 RCX: e2be5d8e187eef00
RDX: 0000000000000000 RSI: ffffffff8a35f9e0 RDI: ffffffff8a79c980
RBP: ffffc9000339f718 R08: ffff888016e7c197 R09: 1ffff11002dcf832
R10: dffffc0000000000 R11: ffffed1002dcf833 R12: dffffc0000000000
R13: ffffc9000339f728 R14: 0000000000000246 R15: ffffc9000339f748
FS:  00007fb613b5a880(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f67189fe000 CR3: 0000000075ad6000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 uncharge_batch+0x249/0x420 mm/memcontrol.c:6905
 __mem_cgroup_uncharge_list+0x93/0xc0 mm/memcontrol.c:7006
 mem_cgroup_uncharge_list include/linux/memcontrol.h:720 [inline]
 release_pages+0x1857/0x1bd0 mm/swap.c:962
 __pagevec_release+0x6d/0xe0 mm/swap.c:983
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x5cd/0x19a0 mm/shmem.c:964
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x1e2/0x9a0 mm/shmem.c:1145
 evict+0x4b6/0x8b0 fs/inode.c:647
 __dentry_kill+0x412/0x630 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x5a5/0x8c0 fs/file_table.c:319
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x10f/0x130 kernel/entry/common.c:181
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fb613c48407
Code: 48 89 fa 4c 89 df e8 38 aa 00 00 8b 93 08 03 00 00 59 5e 48 83 f8 fc 74 1a 5b c3 0f 1f 84 00 00 00 00 00 48 8b 44 24 10 0f 05 <5b> c3 0f 1f 80 00 00 00 00 83 e2 39 83 fa 08 75 de e8 23 ff ff ff
RSP: 002b:00007ffca81e2f70 EFLAGS: 00000202 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 00007fb613b5a880 RCX: 00007fb613c48407
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000008
RBP: 00007fb613b5a6e8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000002
R13: 00005616eff93410 R14: 0000000000000008 R15: 00005616eff8fba0
 </TASK>