============================================ WARNING: possible recursive locking detected 4.14.287-syzkaller #0 Not tainted -------------------------------------------- syz-executor.5/25891 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-executor.5/25891: #0: (console_lock){+.+.}, at: [] do_fb_ioctl+0x81a/0xa70 drivers/video/fbdev/core/fbmem.c:1223 #1: (&fb_info->lock){+.+.}, at: [] lock_fb_info drivers/video/fbdev/core/fbmem.c:82 [inline] #1: (&fb_info->lock){+.+.}, at: [] do_fb_ioctl+0x824/0xa70 drivers/video/fbdev/core/fbmem.c:1224 #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: 0 PID: 25891 Comm: syz-executor.5 Not tainted 4.14.287-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x1b2/0x281 lib/dump_stack.c:58 print_deadlock_bug kernel/locking/lockdep.c:1800 [inline] check_deadlock kernel/locking/lockdep.c:1847 [inline] validate_chain kernel/locking/lockdep.c:2448 [inline] __lock_acquire.cold+0x180/0x97c kernel/locking/lockdep.c:3491 lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 down_read+0x36/0x80 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+0xbc8/0xdc0 drivers/video/fbdev/core/fbmem.c:1065 fbcon_switch+0x3d9/0x19e0 drivers/video/fbdev/core/fbcon.c:2066 redraw_screen+0x32c/0x790 drivers/tty/vt/vt.c:689 fbcon_blank+0x986/0xd50 drivers/video/fbdev/core/fbcon.c:2204 do_unblank_screen+0x1fd/0x4e0 drivers/tty/vt/vt.c:3954 fbcon_fb_blanked drivers/video/fbdev/core/fbcon.c:2928 [inline] fbcon_event_notify+0x1445/0x1760 drivers/video/fbdev/core/fbcon.c:3046 notifier_call_chain+0x108/0x1a0 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:1093 do_fb_ioctl+0x894/0xa70 drivers/video/fbdev/core/fbmem.c:1229 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1253 vfs_ioctl fs/ioctl.c:46 [inline] file_ioctl fs/ioctl.c:500 [inline] do_vfs_ioctl+0x75a/0xff0 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+0x46/0xbb RIP: 0033:0x7f6a36d07109 RSP: 002b:00007f6a3563a168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007f6a36e1a100 RCX: 00007f6a36d07109 RDX: 0000000000000000 RSI: 0000000000004611 RDI: 0000000000000005 RBP: 00007f6a36d6105d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffd640b2c2f R14: 00007f6a3563a300 R15: 0000000000022000 blktrace: Concurrent blktraces are not allowed on nullb0 blktrace: Concurrent blktraces are not allowed on nullb0 blktrace: Concurrent blktraces are not allowed on nullb0 blktrace: Concurrent blktraces are not allowed on nullb0 Restarting kernel threads ... done. Restarting kernel threads ... done. Restarting kernel threads ... done. Restarting kernel threads ... done. Restarting kernel threads ... done. Restarting kernel threads ... done.