INFO: task syz.3.2093:11528 blocked for more than 143 seconds. Not tainted syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:syz.3.2093 state:D stack:28552 pid:11528 ppid:5773 flags:0x00004004 Call Trace: context_switch kernel/sched/core.c:5382 [inline] __schedule+0x15ae/0x4660 kernel/sched/core.c:6701 schedule+0xbd/0x170 kernel/sched/core.c:6775 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6834 __mutex_lock_common kernel/locking/mutex.c:679 [inline] __mutex_lock+0x673/0xc80 kernel/locking/mutex.c:747 write_ports+0xb7/0xfa0 fs/nfsd/nfsctl.c:843 nfsctl_transaction_write+0x10c/0x150 fs/nfsd/nfsctl.c:113 vfs_write+0x299/0x9a0 fs/read_write.c:582 ksys_write+0x151/0x260 fs/read_write.c:637 do_syscall_x64 arch/x86/entry/common.c:46 [inline] do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7fd382f9e1d9 RSP: 002b:00007fd383dad028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fd383225fa0 RCX: 00007fd382f9e1d9 RDX: 0000000000000002 RSI: 0000200000000000 RDI: 0000000000000003 RBP: 00007fd383035888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd383226038 R14: 00007fd383225fa0 R15: 00007fff9f861508 Showing all locks held in the system: 4 locks held by kworker/u4:0/11: #0: ffff88801c663d38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #0: ffff88801c663d38 ((wq_completion)writeback){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 #1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:2632 [inline] #1: ffffc90000107d00 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_scheduled_works+0x975/0x1600 kernel/workqueue.c:2734 #2: ffff88814de620e0 (&type->s_umount_key#32){++++}-{3:3}, at: super_trylock_shared+0x20/0xf0 fs/super.c:607 #3: ffff88814de64c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1768 [inline] #3: ffff88814de64c58 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x1a4/0x350 fs/ext4/inode.c:2821 1 lock held by khungtaskd/29: #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:334 [inline] #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:786 [inline] #0: ffffffff8df320e0 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x55/0x290 kernel/locking/lockdep.c:6669 2 locks held by getty/5526: #0: ffff88814c58f0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243 #1: ffffc9000327e2f0 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x428/0x1370 drivers/tty/n_tty.c:2217 3 locks held by syz-executor/5761: #0: ffff8880778b3aa0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline] #0: ffff8880778b3aa0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline] #0: ffff8880778b3aa0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440 #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6283 #2: ffff88814de66990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448 3 locks held by syz.0.2060/11442: #0: ffff88806594e848 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040 #1: ffff88802f8cc418 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580 #2: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_svc+0x65/0xab0 fs/nfsd/nfssvc.c:788 3 locks held by syz.3.2093/11528: #0: ffff88802cb3d248 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040 #1: ffff88807cb96418 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580 #2: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb7/0xfa0 fs/nfsd/nfsctl.c:843 3 locks held by syz.6.2193/11949: #0: ffff88802cb36ac8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040 #1: ffff88805d534418 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580 #2: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: write_versions+0x96/0xe00 fs/nfsd/nfsctl.c:676 2 locks held by syz.5.2314/12294: #0: ffff88802b9f8ac8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040 #1: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: write_ports+0xb7/0xfa0 fs/nfsd/nfsctl.c:843 2 locks held by syz-executor/12435: #0: ffff888030c620e0 (&type->s_umount_key#62){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline] #0: ffff888030c620e0 (&type->s_umount_key#62){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff888030c620e0 (&type->s_umount_key#62){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513 #1: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x53/0x1a0 fs/nfsd/nfssvc.c:638 2 locks held by kworker/u4:4/12504: 3 locks held by syz.4.2400/12601: #0: ffff88802c6feac8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1040 #1: ffff888027c0a418 (sb_writers#18){.+.+}-{0:0}, at: vfs_write+0x21e/0x9a0 fs/read_write.c:580 #2: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: write_versions+0x96/0xe00 fs/nfsd/nfsctl.c:676 2 locks held by syz-executor/12785: #0: ffff88807ba0e0e0 (&type->s_umount_key#62){+.+.}-{3:3}, at: __super_lock fs/super.c:56 [inline] #0: ffff88807ba0e0e0 (&type->s_umount_key#62){+.+.}-{3:3}, at: __super_lock_excl fs/super.c:71 [inline] #0: ffff88807ba0e0e0 (&type->s_umount_key#62){+.+.}-{3:3}, at: deactivate_super+0xa4/0xe0 fs/super.c:513 #1: ffffffff8e1e1708 (nfsd_mutex){+.+.}-{3:3}, at: nfsd_shutdown_threads+0x53/0x1a0 fs/nfsd/nfssvc.c:638 3 locks held by kworker/u4:6/13962: #0: ffff8880b8c3c258 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x29/0x130 kernel/sched/core.c:559 #1: ffff8880b8c28a00 (psi_seq){-.-.}-{0:0}, at: psi_sched_switch kernel/sched/stats.h:189 [inline] #1: ffff8880b8c28a00 (psi_seq){-.-.}-{0:0}, at: __schedule+0x21d3/0x4660 kernel/sched/core.c:6696 #2: ffff8880b8c295d8 (&base->lock){-.-.}-{2:2}, at: lock_timer_base+0x123/0x270 kernel/time/timer.c:999 3 locks held by syz.2.2776/14190: #0: ffff8880310327a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline] #0: ffff8880310327a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline] #0: ffff8880310327a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440 #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6283 #2: ffff88814de66990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448 3 locks held by syz.0.2782/14205: #0: ffff88807dff6a20 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline] #0: ffff88807dff6a20 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline] #0: ffff88807dff6a20 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440 #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6283 #2: ffff88814de66990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448 3 locks held by syz.7.2783/14211: #0: ffff8880774281a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline] #0: ffff8880774281a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline] #0: ffff8880774281a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440 #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6283 #2: ffff88814de66990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448 3 locks held by syz.3.2785/14216: #0: ffff8880774294a0 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:165 [inline] #0: ffff8880774294a0 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5380 [inline] #0: ffff8880774294a0 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x32/0x2f0 mm/memory.c:5440 #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: __sb_start_write include/linux/fs.h:1633 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: sb_start_pagefault include/linux/fs.h:1737 [inline] #1: ffff88814de62510 (sb_pagefaults){++++}-{0:0}, at: ext4_page_mkwrite+0x1e2/0x11a0 fs/ext4/inode.c:6283 #2: ffff88814de66990 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x1f3f/0x2170 fs/jbd2/transaction.c:448 4 locks held by sed/14439: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 29 Comm: khungtaskd Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/16/2026 Call Trace: dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106 nmi_cpu_backtrace+0x3a6/0x3e0 lib/nmi_backtrace.c:113 nmi_trigger_cpumask_backtrace+0x17a/0x2f0 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+0xf59/0xfa0 kernel/hung_task.c:379 kthread+0x2fa/0x390 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293