============================================ WARNING: possible recursive locking detected 4.19.172-syzkaller #0 Not tainted -------------------------------------------- syz-executor806/8072 is trying to acquire lock: 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:316 [inline] 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:304 [inline] 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:328 [inline] 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: blocking_notifier_call_chain+0x6f/0xa0 syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:325 but task is already holding lock: 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:316 [inline] 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:304 [inline] 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:328 [inline] 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: blocking_notifier_call_chain+0x6f/0xa0 syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:325 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock((fb_notifier_list).rwsem); lock((fb_notifier_list).rwsem); *** DEADLOCK *** May be due to missing lock nesting notation 3 locks held by syz-executor806/8072: #0: 00000000e6c259cd (console_lock){+.+.}, at: do_fb_ioctl+0x772/0xb50 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:1200 #1: 00000000abac736b (&fb_info->lock){+.+.}, at: lock_fb_info syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:81 [inline] #1: 00000000abac736b (&fb_info->lock){+.+.}, at: do_fb_ioctl+0x77c/0xb50 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:1201 #2: 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:316 [inline] #2: 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:304 [inline] #2: 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:328 [inline] #2: 000000000863eac4 ((fb_notifier_list).rwsem){++++}, at: blocking_notifier_call_chain+0x6f/0xa0 syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:325 stack backtrace: CPU: 0 PID: 8072 Comm: syz-executor806 Not tainted 4.19.172-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack syzkaller/managers/linux-4-19/kernel/lib/dump_stack.c:77 [inline] dump_stack+0x1fc/0x2ef syzkaller/managers/linux-4-19/kernel/lib/dump_stack.c:118 print_deadlock_bug syzkaller/managers/linux-4-19/kernel/kernel/locking/lockdep.c:1763 [inline] check_deadlock syzkaller/managers/linux-4-19/kernel/kernel/locking/lockdep.c:1807 [inline] validate_chain syzkaller/managers/linux-4-19/kernel/kernel/locking/lockdep.c:2403 [inline] __lock_acquire.cold+0x121/0x57e syzkaller/managers/linux-4-19/kernel/kernel/locking/lockdep.c:3415 lock_acquire+0x170/0x3c0 syzkaller/managers/linux-4-19/kernel/kernel/locking/lockdep.c:3907 down_read+0x36/0x80 syzkaller/managers/linux-4-19/kernel/kernel/locking/rwsem.c:24 __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:316 [inline] __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:304 [inline] blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:328 [inline] blocking_notifier_call_chain+0x6f/0xa0 syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:325 fb_set_var+0xc51/0xe20 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:1042 fbcon_switch+0x425/0x1ba0 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbcon.c:2085 redraw_screen+0x37d/0x870 syzkaller/managers/linux-4-19/kernel/drivers/tty/vt/vt.c:1015 fbcon_blank+0xae6/0xec0 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbcon.c:2223 do_unblank_screen+0x241/0x610 syzkaller/managers/linux-4-19/kernel/drivers/tty/vt/vt.c:4276 fbcon_fb_blanked syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbcon.c:2970 [inline] fbcon_event_notify+0x1a3a/0x1d80 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbcon.c:3088 notifier_call_chain+0xc0/0x230 syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:93 __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:317 [inline] __blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:304 [inline] blocking_notifier_call_chain syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:328 [inline] blocking_notifier_call_chain+0x85/0xa0 syzkaller/managers/linux-4-19/kernel/kernel/notifier.c:325 fb_blank+0x195/0x1d0 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:1070 do_fb_ioctl+0x7ec/0xb50 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:1206 fb_ioctl+0xdd/0x130 syzkaller/managers/linux-4-19/kernel/drivers/video/fbdev/core/fbmem.c:1230 vfs_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:46 [inline] file_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:501 [inline] do_vfs_ioctl+0xcdb/0x12e0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:688 ksys_ioctl+0x9b/0xc0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:705 __do_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:712 [inline] __se_sys_ioctl syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 [inline] __x64_sys_ioctl+0x6f/0xb0 syzkaller/managers/linux-4-19/kernel/fs/ioctl.c:710 do_syscall_64+0xf9/0x620 syzkaller/managers/linux-4-19/kernel/arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x440029 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffe8d49e18 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00000000000090c5 RCX: 0000000000440029 RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000004 RBP: 0000000000000000 R08: 00007fffe8d49fb8 R09: 00007fffe8d49fb8 R10: 00007fffe8d49fb8 R11: 0000000000000246 R12: 00007fffe8d49e2c R13: 431bde82d7b634db R14: 00000000004ae018 R15: 0000000000400488