============================================ WARNING: possible recursive locking detected 4.14.176-syzkaller #0 Not tainted -------------------------------------------- syz-executor013/6330 is trying to acquire lock: ((fb_notifier_list).rwsem){++++}, at: [] __blocking_notifier_call_chain kernel/notifier.c:316 [inline] ((fb_notifier_list).rwsem){++++}, at: [] __blocking_notifier_call_chain kernel/notifier.c:304 [inline] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain kernel/notifier.c:328 [inline] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 kernel/notifier.c:325 but task is already holding lock: ((fb_notifier_list).rwsem){++++}, at: [] __blocking_notifier_call_chain kernel/notifier.c:316 [inline] ((fb_notifier_list).rwsem){++++}, at: [] __blocking_notifier_call_chain kernel/notifier.c:304 [inline] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain kernel/notifier.c:328 [inline] ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 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-executor013/6330: #0: (console_lock){+.+.}, at: [] do_fb_ioctl+0x143/0x940 drivers/video/fbdev/core/fbmem.c:1212 #1: (&fb_info->lock){+.+.}, at: [] lock_fb_info+0x1a/0x70 drivers/video/fbdev/core/fbmem.c:81 #2: ((fb_notifier_list).rwsem){++++}, at: [] __blocking_notifier_call_chain kernel/notifier.c:316 [inline] #2: ((fb_notifier_list).rwsem){++++}, at: [] __blocking_notifier_call_chain kernel/notifier.c:304 [inline] #2: ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain kernel/notifier.c:328 [inline] #2: ((fb_notifier_list).rwsem){++++}, at: [] blocking_notifier_call_chain+0x63/0x90 kernel/notifier.c:325 stack backtrace: CPU: 1 PID: 6330 Comm: syz-executor013 Not tainted 4.14.176-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x13e/0x194 lib/dump_stack.c:58 print_deadlock_bug kernel/locking/lockdep.c:1796 [inline] check_deadlock kernel/locking/lockdep.c:1843 [inline] validate_chain kernel/locking/lockdep.c:2444 [inline] __lock_acquire.cold+0x2bf/0x8dc kernel/locking/lockdep.c:3487 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3994 down_read+0x37/0xa0 kernel/locking/rwsem.c:24 __blocking_notifier_call_chain kernel/notifier.c:316 [inline] __blocking_notifier_call_chain kernel/notifier.c:304 [inline] blocking_notifier_call_chain kernel/notifier.c:328 [inline] blocking_notifier_call_chain+0x63/0x90 kernel/notifier.c:325 fb_set_var+0xaad/0xc70 drivers/video/fbdev/core/fbmem.c:1054 fbcon_switch+0x4b9/0x1780 drivers/video/fbdev/core/fbcon.c:2235 redraw_screen+0x331/0x770 drivers/tty/vt/vt.c:689 fbcon_blank+0x9b3/0xd60 drivers/video/fbdev/core/fbcon.c:2373 do_unblank_screen drivers/tty/vt/vt.c:3929 [inline] do_unblank_screen+0x1fd/0x4f0 drivers/tty/vt/vt.c:3896 fbcon_fb_blanked drivers/video/fbdev/core/fbcon.c:3214 [inline] fbcon_event_notify+0x1433/0x1746 drivers/video/fbdev/core/fbcon.c:3332 notifier_call_chain+0x107/0x1a0 kernel/notifier.c:93 __blocking_notifier_call_chain kernel/notifier.c:317 [inline] __blocking_notifier_call_chain kernel/notifier.c:304 [inline] blocking_notifier_call_chain kernel/notifier.c:328 [inline] blocking_notifier_call_chain+0x79/0x90 kernel/notifier.c:325 fb_blank+0x14c/0x190 drivers/video/fbdev/core/fbmem.c:1082 do_fb_ioctl+0x196/0x940 drivers/video/fbdev/core/fbmem.c:1218 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1242 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684 SYSC_ioctl fs/ioctl.c:701 [inline] SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x42/0xb7 RIP: 0033:0x4413c9 RSP: 002b:00007ffc5a2a0d38 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004413c9 RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000004 RBP: 0000000000008ac3 R08: 00000000004002c8 R09: 00000000004002c8 R10: 00000000004002c8 R11: 0000000000000246 R12: 00000000004021f0 R13: 0000000000402280 R14: 0000000000000000 R15: 0000000000000000