INFO: task syz-executor.4:19301 blocked for more than 143 seconds. Not tainted 5.7.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D28488 19301 7563 0x20020004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4158 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4217 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103 lock_fb_info include/linux/fb.h:637 [inline] fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 __fput+0x33e/0x880 fs/file_table.c:280 task_work_run+0xf4/0x1b0 kernel/task_work.c:123 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x2fa/0x360 arch/x86/entry/common.c:165 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:279 [inline] do_syscall_32_irqs_on arch/x86/entry/common.c:340 [inline] do_fast_syscall_32+0xbef/0xe90 arch/x86/entry/common.c:396 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 INFO: task syz-executor.2:19307 blocked for more than 143 seconds. Not tainted 5.7.0-rc3-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.2 D26312 19307 7298 0x20024004 Call Trace: schedule+0xd0/0x2a0 kernel/sched/core.c:4158 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:4217 __mutex_lock_common kernel/locking/mutex.c:1033 [inline] __mutex_lock+0x7ab/0x13c0 kernel/locking/mutex.c:1103 lock_fb_info include/linux/fb.h:637 [inline] fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418 chrdev_open+0x219/0x5c0 fs/char_dev.c:414 do_dentry_open+0x4ba/0x1290 fs/open.c:797 do_open fs/namei.c:3229 [inline] path_openat+0x1e59/0x27d0 fs/namei.c:3346 do_filp_open+0x192/0x260 fs/namei.c:3373 do_sys_openat2+0x585/0x7d0 fs/open.c:1148 do_sys_open+0xc3/0x140 fs/open.c:1164 do_syscall_32_irqs_on arch/x86/entry/common.c:337 [inline] do_fast_syscall_32+0x270/0xe90 arch/x86/entry/common.c:396 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139 Showing all locks held in the system: 1 lock held by khungtaskd/1133: #0: ffffffff899beb00 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x53/0x260 kernel/locking/lockdep.c:5754 1 lock held by in:imklog/6779: #0: ffff88808e9220f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe9/0x100 fs/file.c:826 2 locks held by kworker/u4:9/15187: 5 locks held by kworker/u4:11/15191: 2 locks held by syz-executor.3/19305: 1 lock held by syz-executor.4/19301: #0: ffff8880a345b078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a345b078 (&fb_info->lock){+.+.}-{3:3}, at: fb_release+0x4e/0x140 drivers/video/fbdev/core/fbmem.c:1447 1 lock held by syz-executor.2/19307: #0: ffff8880a345b078 (&fb_info->lock){+.+.}-{3:3}, at: lock_fb_info include/linux/fb.h:637 [inline] #0: ffff8880a345b078 (&fb_info->lock){+.+.}-{3:3}, at: fb_open+0xd3/0x430 drivers/video/fbdev/core/fbmem.c:1418 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1133 Comm: khungtaskd Not tainted 5.7.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x188/0x20d lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline] watchdog+0xa8c/0x1010 kernel/hung_task.c:289 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 15187 Comm: kworker/u4:9 Not tainted 5.7.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_dat_purge RIP: 0010:__read_once_size include/linux/compiler.h:199 [inline] RIP: 0010:check_kcov_mode kernel/kcov.c:155 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x1c/0x50 kernel/kcov.c:187 Code: 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 65 48 8b 04 25 00 1f 02 00 65 8b 15 18 f0 8e 7e 81 e2 00 01 1f 00 48 8b 34 24 75 2b <8b> 90 d8 13 00 00 83 fa 02 75 20 48 8b 88 e0 13 00 00 8b 80 dc 13 RSP: 0018:ffffc9000870fc68 EFLAGS: 00000046 RAX: ffff88805fbf4340 RBX: 0000000000000201 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff8399fedb RDI: ffffffff882a4840 RBP: ffffffff87b35030 R08: 0000000000000001 R09: ffffed100aec4b21 R10: ffff888057625903 R11: ffffed100aec4b20 R12: ffffffff882a4840 R13: ffff8880575b0b20 R14: ffffffff87b34470 R15: 0000000000000164 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000556aace83160 CR3: 00000000a8050000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: check_preemption_disabled lib/smp_processor_id.c:14 [inline] __this_cpu_preempt_check+0xb/0x190 lib/smp_processor_id.c:64 __local_bh_enable_ip+0x1e6/0x270 kernel/softirq.c:184 spin_unlock_bh include/linux/spinlock.h:398 [inline] __batadv_dat_purge.isra.0.part.0+0x230/0x350 net/batman-adv/distributed-arp-table.c:185 __batadv_dat_purge net/batman-adv/distributed-arp-table.c:166 [inline] batadv_dat_purge+0x49/0x70 net/batman-adv/distributed-arp-table.c:204 process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 worker_thread+0x96/0xe20 kernel/workqueue.c:2414 kthread+0x388/0x470 kernel/kthread.c:268 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352