================================================ 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: __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 ---------------- 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