INFO: task kworker/u4:4:1243 blocked for more than 143 seconds. Not tainted 5.15.164-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:kworker/u4:4 state:D stack:23968 pid: 1243 ppid: 2 flags:0x00004000 Workqueue: writeback wb_workfn (flush-7:3) Call Trace: context_switch kernel/sched/core.c:5030 [inline] __schedule+0x12c4/0x45b0 kernel/sched/core.c:6376 schedule+0x11b/0x1f0 kernel/sched/core.c:6459 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6518 __mutex_lock_common+0xe34/0x25a0 kernel/locking/mutex.c:669 __mutex_lock kernel/locking/mutex.c:729 [inline] mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743 jfs_commit_inode+0x242/0x580 fs/jfs/inode.c:102 jfs_write_inode+0x13f/0x210 fs/jfs/inode.c:132 write_inode fs/fs-writeback.c:1495 [inline] __writeback_single_inode+0x644/0xe30 fs/fs-writeback.c:1705 writeback_sb_inodes+0xbce/0x1a40 fs/fs-writeback.c:1930 __writeback_inodes_wb+0x114/0x400 fs/fs-writeback.c:2001 wb_writeback+0x465/0xc50 fs/fs-writeback.c:2106 wb_check_background_flush fs/fs-writeback.c:2172 [inline] wb_do_writeback fs/fs-writeback.c:2260 [inline] wb_workfn+0xd07/0x1130 fs/fs-writeback.c:2288 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Showing all locks held in the system: 1 lock held by khungtaskd/27: #0: ffffffff8c91fb20 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30 4 locks held by kworker/u4:4/1243: #0: ffff888012a8d138 ((wq_completion)writeback){+.+.}-{0:0}, at: process_one_work+0x78a/0x10c0 kernel/workqueue.c:2283 #1: ffffc9000596fd20 ((work_completion)(&(&wb->dwork)->work)){+.+.}-{0:0}, at: process_one_work+0x7d0/0x10c0 kernel/workqueue.c:2285 #2: ffff8880607000e0 (&type->s_umount_key#59){.+.+}-{3:3}, at: trylock_super+0x1b/0xf0 fs/super.c:418 #3: ffff888061f03008 (&jfs_ip->commit_mutex){+.+.}-{3:3}, at: jfs_commit_inode+0x242/0x580 fs/jfs/inode.c:102 2 locks held by udevd/3028: #0: ffff88801c83e118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:912 #1: ffff8881474ef468 (&lo->lo_mutex){+.+.}-{3:3}, at: lo_release+0x4d/0x1f0 drivers/block/loop.c:2070 2 locks held by getty/3329: #0: ffff88814b5f8098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252 #1: ffffc9000229b2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x6af/0x1db0 drivers/tty/n_tty.c:2158 2 locks held by syz-executor/3569: #0: ffff88801c835118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_put+0xfb/0x790 block/bdev.c:912 #1: ffff8881474e9468 (&lo->lo_mutex){+.+.}-{3:3}, at: __loop_clr_fd+0xa9/0xbe0 drivers/block/loop.c:1365 4 locks held by syz.3.4/3667: 1 lock held by syz.1.441/6147: 1 lock held by syz.4.442/6155: #0: ffff88801c83e118 (&disk->open_mutex){+.+.}-{3:3}, at: blkdev_get_by_dev+0x14d/0xa50 block/bdev.c:817 2 locks held by syz.3.443/6157: ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 27 Comm: khungtaskd Not tainted 5.15.164-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106 nmi_cpu_backtrace+0x46a/0x4a0 lib/nmi_backtrace.c:111 nmi_trigger_cpumask_backtrace+0x181/0x2a0 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:210 [inline] watchdog+0xe72/0xeb0 kernel/hung_task.c:295 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 3987 Comm: kworker/1:14 Not tainted 5.15.164-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024 Workqueue: events nsim_dev_trap_report_work RIP: 0010:native_save_fl arch/x86/include/asm/irqflags.h:35 [inline] RIP: 0010:arch_local_save_flags arch/x86/include/asm/irqflags.h:70 [inline] RIP: 0010:arch_irqs_disabled arch/x86/include/asm/irqflags.h:132 [inline] RIP: 0010:debug_check_no_locks_freed+0x265/0x4a0 kernel/locking/lockdep.c:6418 Code: 80 3c 13 00 74 12 4c 89 f7 e8 e7 36 67 00 48 ba 00 00 00 00 00 fc ff df 48 c7 44 24 60 00 00 00 00 9c 8f 44 24 60 80 3c 13 00 <74> 12 4c 89 f7 e8 41 36 67 00 48 ba 00 00 00 00 00 fc ff df f6 44 RSP: 0018:ffffc900032f7920 EFLAGS: 00000046 RAX: 0000000000000000 RBX: 1ffff9200065ef30 RCX: ffffc900032f7a7c RDX: dffffc0000000000 RSI: 0000000000001000 RDI: ffff888057202000 RBP: ffffc900032f7a18 R08: ffffffff81398c58 R09: fffffbfff1bd2986 R10: 0000000000000000 R11: dffffc0000000001 R12: 000000000000000f R13: 1ffff1100490c15d R14: ffffc900032f7980 R15: 0000000000000004 FS: 0000000000000000(0000) GS:ffff8880b9b00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055a0a982b2e8 CR3: 000000007997c000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: slab_free_hook mm/slub.c:1677 [inline] slab_free_freelist_hook+0x73/0x160 mm/slub.c:1731 slab_free mm/slub.c:3499 [inline] kfree+0xf1/0x270 mm/slub.c:4559 skb_free_head net/core/skbuff.c:655 [inline] skb_release_data+0x73a/0x8a0 net/core/skbuff.c:677 skb_release_all net/core/skbuff.c:742 [inline] __kfree_skb net/core/skbuff.c:756 [inline] consume_skb+0xa3/0x140 net/core/skbuff.c:914 nsim_dev_trap_report drivers/net/netdevsim/dev.c:737 [inline] nsim_dev_trap_report_work+0x788/0xab0 drivers/net/netdevsim/dev.c:762 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2310 worker_thread+0xaca/0x1280 kernel/workqueue.c:2457 kthread+0x3f6/0x4f0 kernel/kthread.c:334 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287