syzbot

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WARNING: lock held when returning to user space!
syzkaller #0 Not tainted
------------------------------------------------
udevd/4966 is leaving the kernel with locks still held!
1 lock held by udevd/4966:
 #0: ffffffff8dfc8140 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
 #0: ffffffff8dfc8140 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
 #0: ffffffff8dfc8140 (rcu_read_lock){....}-{1:3}, at: __pte_offset_map+0x29/0x200 mm/pgtable-generic.c:290
------------[ cut here ]------------
Voluntary context switch within RCU read-side critical section!
WARNING: kernel/rcu/tree_plugin.h:332 at rcu_note_context_switch+0xcac/0xf40 kernel/rcu/tree_plugin.h:332, CPU#1: udevd/4966
Modules linked in:
CPU: 1 UID: 0 PID: 4966 Comm: udevd Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:rcu_note_context_switch+0xcac/0xf40 kernel/rcu/tree_plugin.h:332
Code: 00 41 c6 45 00 00 48 8b 3d c1 52 de 0d 48 81 c4 b8 00 00 00 5b 41 5c 41 5d 41 5e 41 5f 5d e9 bb 5f ff ff 48 8d 3d 84 13 e2 0d <67> 48 0f b9 3a e9 1b f4 ff ff 90 0f 0b 90 45 84 e4 0f 84 ea f3 ff
RSP: 0000:ffffc90003b07b90 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff8880381b5c40 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8ba74c40 RDI: ffffffff8f8c4110
RBP: dffffc0000000000 R08: ffffffff8f88d2f7 R09: 1ffffffff1f11a5e
R10: dffffc0000000000 R11: fffffbfff1f11a5f R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880b893c800 R15: ffff8880381b6104
FS:  00007f175e59e880(0000) GS:ffff88812627c000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055db9d6aca58 CR3: 0000000038f02000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __schedule+0x291/0x54c0 kernel/sched/core.c:7043
 __schedule_loop kernel/sched/core.c:7267 [inline]
 schedule+0x164/0x360 kernel/sched/core.c:7282
 __exit_to_user_mode_loop kernel/entry/common.c:54 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:252 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:323 [inline]
 irqentry_exit+0x263/0x730 kernel/entry/common.c:162
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697
RIP: 0033:0x7f175e69dc3b
Code: 83 c5 6e 4c 39 fa 0f 85 1c f6 ff ff e9 f6 f9 ff ff 66 0f 1f 44 00 00 48 8d 3d 42 95 0f 00 e8 5c c6 ff ff 48 8d 05 85 8e 13 00 <4b> 83 4c 35 08 01 48 39 c5 0f 84 49 ff ff ff 49 83 4d 08 04 e9 3f
RSP: 002b:00007ffd6c468110 EFLAGS: 00010293
RAX: 00007f175e7d6ac0 RBX: 0000000000000020 RCX: 0000000000000010
RDX: 000055db9d6b51d0 RSI: 00007f175e7d6b40 RDI: 000055db9d6aca20
RBP: 00007f175e7d6ac0 R08: 00007f175e7d6ac0 R09: 0000000000000020
R10: 0000000000000000 R11: 0000000000000003 R12: 0000000000000011
R13: 000055db9d6aca20 R14: 0000000000000030 R15: 00007f175e7d6b20
 </TASK>
----------------
Code disassembly (best guess):
   0:	00 41 c6             	add    %al,-0x3a(%rcx)
   3:	45 00 00             	add    %r8b,(%r8)
   6:	48 8b 3d c1 52 de 0d 	mov    0xdde52c1(%rip),%rdi        # 0xdde52ce
   d:	48 81 c4 b8 00 00 00 	add    $0xb8,%rsp
  14:	5b                   	pop    %rbx
  15:	41 5c                	pop    %r12
  17:	41 5d                	pop    %r13
  19:	41 5e                	pop    %r14
  1b:	41 5f                	pop    %r15
  1d:	5d                   	pop    %rbp
  1e:	e9 bb 5f ff ff       	jmp    0xffff5fde
  23:	48 8d 3d 84 13 e2 0d 	lea    0xde21384(%rip),%rdi        # 0xde213ae
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	e9 1b f4 ff ff       	jmp    0xfffff44f
  34:	90                   	nop
  35:	0f 0b                	ud2
  37:	90                   	nop
  38:	45 84 e4             	test   %r12b,%r12b
  3b:	0f                   	.byte 0xf
  3c:	84 ea                	test   %ch,%dl
  3e:	f3                   	repz
  3f:	ff                   	.byte 0xff