From: syzbot <syzbot+2e8b7c8cf82134e81378@syzkaller.appspotmail.com>
To: Liam.Howlett@oracle.com, akpm@linux-foundation.org,
david@kernel.org, linux-kernel@vger.kernel.org,
linux-mm@kvack.org, ljs@kernel.org, mhocko@suse.com,
rppt@kernel.org, surenb@google.com,
syzkaller-bugs@googlegroups.com, vbabka@kernel.org
Subject: [syzbot] [mm?] WARNING: lock held when returning to user space in __pte_offset_map
Date: Sat, 25 Apr 2026 02:32:34 -0700 [thread overview]
Message-ID: <69ec8a32.a00a0220.1901e8.000b.GAE@google.com> (raw)
Hello,
syzbot found the following issue on:
HEAD commit: dd6c438c3e64 Merge tag 'vfs-7.1-rc1.fixes' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=145bec36580000
kernel config: https://syzkaller.appspot.com/x/.config?x=ed9f32dc64d6a2f2
dashboard link: https://syzkaller.appspot.com/bug?extid=2e8b7c8cf82134e81378
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/926b34cf03cd/disk-dd6c438c.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/020eae7c763c/vmlinux-dd6c438c.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f652b84678d/bzImage-dd6c438c.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2e8b7c8cf82134e81378@syzkaller.appspotmail.com
================================================
WARNING: lock held when returning to user space!
syzkaller #0 Not tainted
------------------------------------------------
udevd/5800 is leaving the kernel with locks still held!
1 lock held by udevd/5800:
#0: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8dfc80c0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:838 [inline]
#0: ffffffff8dfc80c0 (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#0: udevd/5800
Modules linked in:
CPU: 0 UID: 0 PID: 5800 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 21 24 e1 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 24 e7 e4 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:ffffc90004477b90 EFLAGS: 00010002
RAX: 0000000000000000 RBX: ffff888039ac9ec0 RCX: 0000000000000002
RDX: 0000000000000000 RSI: ffffffff8ba73c40 RDI: ffffffff8f8f4250
RBP: dffffc0000000000 R08: ffffffff8f8bd1f7 R09: 1ffffffff1f17a3e
R10: dffffc0000000000 R11: fffffbfff1f17a3f R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880b883c800 R15: ffff888039aca384
FS: 00007f74fc12d880(0000) GS:ffff8881260fb000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055de63bc0d08 CR3: 0000000031232000 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: 0033:0x7f74fc8d1a9a
Code: 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 53 48 85 ff 74 2f 48 8b 47 08 48 39 c7 74 21 48 8b 1f 48 39 df 74 19 48 89 18 <48> 89 43 08 e8 8d d9 ff ff 48 89 d8 5b c3 0f 1f 84 00 00 00 00 00
RSP: 002b:00007ffceb76a200 EFLAGS: 00010283
RAX: 000055de63bbd0b0 RBX: 000055de63bc0d00 RCX: 0000000000000000
RDX: 000055de63bbf070 RSI: 000055de63bc5ae0 RDI: 000055de63bbcf10
RBP: 000055de63bbcf10 R08: 000055de63bc5af0 R09: 0000000000000003
R10: 0000000000000000 R11: 0000000000000297 R12: 000055de3e623588
R13: 00007ffceb76a2b0 R14: 0000000000000000 R15: 0000000000000000
</TASK>
----------------
Code disassembly (best guess):
0: 00 41 c6 add %al,-0x3a(%rcx)
3: 45 00 00 add %r8b,(%r8)
6: 48 8b 3d 21 24 e1 0d mov 0xde12421(%rip),%rdi # 0xde1242e
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 24 e7 e4 0d lea 0xde4e724(%rip),%rdi # 0xde4e74e
* 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
---
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reply other threads:[~2026-04-25 9:32 UTC|newest]
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