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AJvYcCV/okO1ifkY/j2qgq5JipRySvfaD2zBC35xkPitpdQgUoCirj4wIQClB7Vjd2cqXbcPoIARy/oq/1HMY+U=@vger.kernel.org X-Gm-Message-State: AOJu0YxBpSMDiCf+QR51Hal5LLfxfSyjSRnA7ildoaJ3XMnw30CoBHyX MT4cxn1g/ibOjln8ifBJdld2AxakSwlwFBrD1F4jGXIZWrKdwSFRmIYlOdMC0yJBay8OkGGhM7D hjOaCjJrPPfzsl8L+vZDvPMc9lek8BnNQyjBMgsGR8QAtstw3EtXSOwJDlqc= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:1302:b0:467:e7b:6fc4 with SMTP id 5614622812f47-467575dca9dmr8294142b6e.45.1773719541163; Mon, 16 Mar 2026 20:52:21 -0700 (PDT) Date: Mon, 16 Mar 2026 20:52:21 -0700 In-Reply-To: <69af0a05.050a0220.310d8.002f.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69b8cff5.050a0220.248e02.0123.GAE@google.com> Subject: Re: [syzbot] [kernel?] WARNING in _cpu_down From: syzbot To: daniel.m.jordan@oracle.com, linux-kernel@vger.kernel.org, peterz@infradead.org, steffen.klassert@secunet.com, syzkaller-bugs@googlegroups.com, tglx@kernel.org Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 2d1373e4246d Merge tag 'for-7.0-rc4-tag' of git://git.kern.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16b93d52580000 kernel config: https://syzkaller.appspot.com/x/.config?x=64e78d99d9bf8b4c dashboard link: https://syzkaller.appspot.com/bug?extid=123e1b70473ce213f3af compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10d358ba580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=129dc4da580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/2ccba0c603a6/disk-2d1373e4.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/6aaccd7990b8/vmlinux-2d1373e4.xz kernel image: https://storage.googleapis.com/syzbot-assets/78e3c8cc74dc/bzImage-2d1373e4.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+123e1b70473ce213f3af@syzkaller.appspotmail.com smpboot: CPU 1 is now offline smpboot: Booting Node 0 Processor 1 APIC 0x1 ------------[ cut here ]------------ DEAD callback error for CPU1 WARNING: kernel/cpu.c:1463 at _cpu_down+0x759/0x1020 kernel/cpu.c:1463, CPU#0: syz.0.17/6077 Modules linked in: CPU: 0 UID: 0 PID: 6077 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 RIP: 0010:_cpu_down+0x75c/0x1020 kernel/cpu.c:1463 Code: 5e 7a f6 89 ee bf 91 00 00 00 e8 df 58 7a f6 81 fd 91 00 00 00 0f 84 6b 02 00 00 e8 1e 5e 7a f6 48 8d 3d f7 f4 4e 05 44 89 ee <67> 48 0f b9 3a e9 3a fa ff ff 45 31 ff e9 32 fa ff ff e8 fd 5d 7a RSP: 0000:ffffc90003007aa8 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff8880b85242e0 RCX: ffffffff8b8dba31 RDX: ffff888032059e80 RSI: 0000000000000001 RDI: ffffffff90dcaf40 RBP: 0000000000000092 R08: 0000000000000005 R09: 0000000000000091 R10: 0000000000000092 R11: 0000000000000001 R12: 00000000000000ed R13: 0000000000000001 R14: 0000000000000001 R15: 00000000fffffff5 FS: 00007f99429dd6c0(0000) GS:ffff88812434a000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fff5c7ffd88 CR3: 00000000747b2000 CR4: 00000000003526f0 Call Trace: cpu_down_maps_locked kernel/cpu.c:1483 [inline] cpu_down kernel/cpu.c:1491 [inline] cpu_device_down+0x82/0xc0 kernel/cpu.c:1508 device_offline drivers/base/core.c:4196 [inline] device_offline+0x2a7/0x3c0 drivers/base/core.c:4180 online_store+0xd1/0x180 drivers/base/core.c:2809 dev_attr_store+0x58/0x80 drivers/base/core.c:2437 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142 kernfs_fop_write_iter+0x3e0/0x5f0 fs/kernfs/file.c:352 new_sync_write fs/read_write.c:595 [inline] vfs_write+0x6ac/0x1070 fs/read_write.c:688 ksys_write+0x12a/0x250 fs/read_write.c:740 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x106/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f994339c799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f99429dd028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007f9943616090 RCX: 00007f994339c799 RDX: 000000000000000b RSI: 00002000000002c0 RDI: 0000000000000003 RBP: 00007f9943432c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9943616128 R14: 00007f9943616090 R15: 00007ffc2a4e69a8 ---------------- Code disassembly (best guess): 0: 5e pop %rsi 1: 7a f6 jp 0xfffffff9 3: 89 ee mov %ebp,%esi 5: bf 91 00 00 00 mov $0x91,%edi a: e8 df 58 7a f6 call 0xf67a58ee f: 81 fd 91 00 00 00 cmp $0x91,%ebp 15: 0f 84 6b 02 00 00 je 0x286 1b: e8 1e 5e 7a f6 call 0xf67a5e3e 20: 48 8d 3d f7 f4 4e 05 lea 0x54ef4f7(%rip),%rdi # 0x54ef51e 27: 44 89 ee mov %r13d,%esi * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: e9 3a fa ff ff jmp 0xfffffa6e 34: 45 31 ff xor %r15d,%r15d 37: e9 32 fa ff ff jmp 0xfffffa6e 3c: e8 .byte 0xe8 3d: fd std 3e: 5d pop %rbp 3f: 7a .byte 0x7a --- 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.