syzbot has found a reproducer for the following issue on: HEAD commit: 8155b4ef3466 Add linux-next specific files for 20241220 git tree: linux-next console output: https://syzkaller.appspot.com/x/log.txt?x=175106df980000 kernel config: https://syzkaller.appspot.com/x/.config?x=9c90bb7161a56c88 dashboard link: https://syzkaller.appspot.com/bug?extid=5b9d613904b2f185f2fe compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16dc4af8580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11dc4af8580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/98a974fc662d/disk-8155b4ef.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/2dea9b72f624/vmlinux-8155b4ef.xz kernel image: https://storage.googleapis.com/syzbot-assets/593a42b9eb34/bzImage-8155b4ef.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+5b9d613904b2f185f2fe@xxxxxxxxxxxxxxxxxxxxxxxxx ------------[ cut here ]------------ WARNING: CPU: 1 PID: 18491 at fs/namespace.c:163 mnt_ns_release+0x15d/0x1c0 fs/namespace.c:163 Modules linked in: CPU: 1 UID: 0 PID: 18491 Comm: syz-executor346 Not tainted 6.13.0-rc3-next-20241220-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024 RIP: 0010:mnt_ns_release+0x15d/0x1c0 fs/namespace.c:163 Code: 15 bf 01 00 00 00 89 ee e8 d0 e8 7d ff 85 ed 7e 39 e8 87 e4 7d ff 4c 89 ff 5b 41 5e 41 5f 5d e9 39 be d8 ff e8 74 e4 7d ff 90 <0f> 0b 90 e9 12 ff ff ff e8 66 e4 7d ff 48 89 df be 03 00 00 00 5b RSP: 0018:ffffc90000a18bb8 EFLAGS: 00010246 RAX: ffffffff82413fac RBX: 0000000000000001 RCX: ffff888022f98000 RDX: 0000000000000100 RSI: 0000000000000001 RDI: 0000000000000001 RBP: ffffc90000a18e10 R08: ffffffff82413eb2 R09: 1ffffffff285af0b R10: dffffc0000000000 R11: ffffffff82424530 R12: ffffffff81a6a6d7 R13: ffff88807a8b4e58 R14: dffffc0000000000 R15: ffff88807a8b4e00 FS: 000055556221c380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ff70e84301d CR3: 0000000032e1a000 CR4: 00000000003526f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <IRQ> rcu_do_batch kernel/rcu/tree.c:2546 [inline] rcu_core+0xaaa/0x17a0 kernel/rcu/tree.c:2802 handle_softirqs+0x2d4/0x9b0 kernel/softirq.c:561 __do_softirq kernel/softirq.c:595 [inline] invoke_softirq kernel/softirq.c:435 [inline] __irq_exit_rcu+0xf7/0x220 kernel/softirq.c:662 irq_exit_rcu+0x9/0x30 kernel/softirq.c:678 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1049 [inline] sysvec_apic_timer_interrupt+0xa6/0xc0 arch/x86/kernel/apic/apic.c:1049 </IRQ> <TASK> asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702 RIP: 0010:lock_acquire+0x264/0x550 kernel/locking/lockdep.c:5853 Code: 2b 00 74 08 4c 89 f7 e8 0a 13 8b 00 f6 44 24 61 02 0f 85 85 01 00 00 41 f7 c7 00 02 00 00 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 25 00 00 00 00 00 43 c7 44 25 09 00 00 00 00 43 c7 44 25 RSP: 0018:ffffc90004c3fac0 EFLAGS: 00000206 RAX: 0000000000000001 RBX: 1ffff92000987f64 RCX: ffff888022f98ae0 RDX: dffffc0000000000 RSI: ffffffff8c0aaba0 RDI: ffffffff8c5fed00 RBP: ffffc90004c3fc10 R08: ffffffff942d7857 R09: 1ffffffff285af0a R10: dffffc0000000000 R11: fffffbfff285af0b R12: 1ffff92000987f60 R13: dffffc0000000000 R14: ffffc90004c3fb20 R15: 0000000000000246 do_write_seqcount_begin_nested include/linux/seqlock.h:476 [inline] do_write_seqcount_begin include/linux/seqlock.h:502 [inline] write_seqlock include/linux/seqlock.h:876 [inline] mnt_ns_tree_write_lock fs/namespace.c:133 [inline] mnt_ns_tree_add+0x52/0x340 fs/namespace.c:145 copy_mnt_ns+0x857/0x960 fs/namespace.c:4044 create_new_namespaces+0xd3/0x7b0 kernel/nsproxy.c:78 unshare_nsproxy_namespaces+0x124/0x180 kernel/nsproxy.c:228 ksys_unshare+0x57d/0xa70 kernel/fork.c:3331 __do_sys_unshare kernel/fork.c:3402 [inline] __se_sys_unshare kernel/fork.c:3400 [inline] __x64_sys_unshare+0x38/0x40 kernel/fork.c:3400 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff70e7faaa9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffec6e71348 EFLAGS: 00000246 ORIG_RAX: 0000000000000110 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff70e7faaa9 RDX: 00007ff70e7f9ce0 RSI: 0000000000000012 RDI: 000000002c060000 RBP: 00000000000f4240 R08: 0000000000000000 R09: 00000000000000a0 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000001975b R13: 00007ffec6e7135c R14: 00007ffec6e71370 R15: 00007ffec6e71360 </TASK> ---------------- Code disassembly (best guess): 0: 2b 00 sub (%rax),%eax 2: 74 08 je 0xc 4: 4c 89 f7 mov %r14,%rdi 7: e8 0a 13 8b 00 call 0x8b1316 c: f6 44 24 61 02 testb $0x2,0x61(%rsp) 11: 0f 85 85 01 00 00 jne 0x19c 17: 41 f7 c7 00 02 00 00 test $0x200,%r15d 1e: 74 01 je 0x21 20: fb sti 21: 48 c7 44 24 40 0e 36 movq $0x45e0360e,0x40(%rsp) 28: e0 45 * 2a: 4b c7 44 25 00 00 00 movq $0x0,0x0(%r13,%r12,1) <-- trapping instruction 31: 00 00 33: 43 c7 44 25 09 00 00 movl $0x0,0x9(%r13,%r12,1) 3a: 00 00 3c: 43 rex.XB 3d: c7 .byte 0xc7 3e: 44 rex.R 3f: 25 .byte 0x25 --- If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing.