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Wed, 05 Aug 2026 23:39:30 -0700 In-Reply-To: <6a707c4f.13bfb6d0.1ecdd5.027e.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a742c22.9c11d2ce.289b96.0095.GAE@google.com> Subject: Re: [syzbot] [trace?] WARNING in trace_rb_cpu_prepare From: syzbot To: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, mhiramat@kernel.org, rostedt@goodmis.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 0d8395707651 Merge tag 'soc-fixes-7.2-2' of git://git.kern.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=164dbbb9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=145fa60d73086782 dashboard link: https://syzkaller.appspot.com/bug?extid=fbe07bcf949966f3c00f 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=115077b9580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/6ecb6d42b95f/disk-0d839570.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/53481594a62a/vmlinux-0d839570.xz kernel image: https://storage.googleapis.com/syzbot-assets/11ad64300b74/bzImage-0d839570.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+fbe07bcf949966f3c00f@syzkaller.appspotmail.com ------------[ cut here ]------------ failed to allocate ring buffer on CPU 1 WARNING: kernel/trace/ring_buffer.c:7976 at trace_rb_cpu_prepare+0x458/0x500 kernel/trace/ring_buffer.c:7976, CPU#1: syz.1.24/6005 Modules linked in: CPU: 1 UID: 0 PID: 6005 Comm: syz.1.24 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026 RIP: 0010:trace_rb_cpu_prepare+0x45a/0x500 kernel/trace/ring_buffer.c:7976 Code: 48 c1 ea 03 80 3c 02 00 0f 84 c7 fc ff ff 48 8b 3c 24 e8 29 0e 6c 00 e9 b9 fc ff ff e8 ff 83 fb ff 48 8d 3d b8 cc 17 0f 89 ee <67> 48 0f b9 3a bb f4 ff ff ff e9 df fd ff ff 4c 89 ef e8 ff 0d 6c RSP: 0018:ffffc900036bf8c0 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff88807a7604b8 RCX: ffff88807bafcf88 RDX: ffff88807b2dca80 RSI: 0000000000000001 RDI: ffffffff9126ada0 RBP: 0000000000000001 R08: ffff88807bafcf88 R09: 0000000000000000 R10: 0000000000000001 R11: ffffffff81000130 R12: 0000000000000001 R13: ffff88807a760410 R14: 0000000000000008 R15: 0000000000000162 FS: 00007f7d853056c0(0000) GS:ffff888123ed8000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f118d5e5ff8 CR3: 000000006ff97000 CR4: 00000000003526f0 Call Trace: cpuhp_invoke_callback+0x205/0x9a0 kernel/cpu.c:204 cpuhp_issue_call+0x1b8/0x970 kernel/cpu.c:2354 __cpuhp_state_add_instance_cpuslocked+0x2d7/0x400 kernel/cpu.c:2423 __cpuhp_state_add_instance+0xd7/0x2d0 kernel/cpu.c:2444 cpuhp_state_add_instance include/linux/cpuhotplug.h:384 [inline] alloc_buffer+0x76c/0x1800 kernel/trace/ring_buffer.c:2830 __ring_buffer_alloc+0x2d/0x40 kernel/trace/ring_buffer.c:2872 allocate_trace_buffer+0x150/0xa30 kernel/trace/trace.c:8412 allocate_trace_buffers kernel/trace/trace.c:8445 [inline] trace_array_create_systems+0x582/0xc30 kernel/trace/trace.c:8623 trace_array_create kernel/trace/trace.c:8666 [inline] instance_mkdir+0xca/0x140 kernel/trace/trace.c:8681 tracefs_syscall_mkdir+0x10e/0x180 fs/tracefs/inode.c:121 vfs_mkdir+0x361/0x850 fs/namei.c:5276 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309 __do_sys_mkdirat fs/namei.c:5330 [inline] __se_sys_mkdirat fs/namei.c:5327 [inline] __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f7d8439e0d9 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:00007f7d85305028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102 RAX: ffffffffffffffda RBX: 00007f7d84626090 RCX: 00007f7d8439e0d9 RDX: 00000000000001ff RSI: 0000200000000140 RDI: ffffffffffffff9c RBP: 00007f7d84435024 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f7d84626128 R14: 00007f7d84626090 R15: 00007ffdb6812d48 ---------------- Code disassembly (best guess): 0: 48 c1 ea 03 shr $0x3,%rdx 4: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) 8: 0f 84 c7 fc ff ff je 0xfffffcd5 e: 48 8b 3c 24 mov (%rsp),%rdi 12: e8 29 0e 6c 00 call 0x6c0e40 17: e9 b9 fc ff ff jmp 0xfffffcd5 1c: e8 ff 83 fb ff call 0xfffb8420 21: 48 8d 3d b8 cc 17 0f lea 0xf17ccb8(%rip),%rdi # 0xf17cce0 28: 89 ee mov %ebp,%esi * 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction 2f: bb f4 ff ff ff mov $0xfffffff4,%ebx 34: e9 df fd ff ff jmp 0xfffffe18 39: 4c 89 ef mov %r13,%rdi 3c: e8 .byte 0xe8 3d: ff .byte 0xff 3e: 0d .byte 0xd 3f: 6c insb (%dx),%es:(%rdi) --- 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.