WARNING in trace_rb_cpu_prepare

Status: upstream: reported on 2026/08/01 23:00
Reported-by: syzbot+b8c64aaf011042278a71@syzkaller.appspotmail.com
First crash: 7d20h, last: 14h22m
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream WARNING in trace_rb_cpu_prepare prio:low trace -1 syz 428 now 6d07h 0/29 upstream: reported syz repro on 2026/08/03 11:32
android-6-12 WARNING in trace_rb_cpu_prepare -1 3 1d16h 8d12h 0/1 premoderation: reported on 2026/08/01 06:47
linux-6.6 WARNING in trace_rb_cpu_prepare -1 4 1d05h 8d09h 0/2 upstream: reported on 2026/08/01 09:59
linux-6.1 WARNING in trace_rb_cpu_prepare -1 2 1d04h 1d09h 0/3 upstream: reported on 2026/08/08 09:55

Sample crash report:
------------[ cut here ]------------
failed to allocate ring buffer on CPU 0
WARNING: CPU: 1 PID: 13374 at kernel/trace/ring_buffer.c:5821 trace_rb_cpu_prepare+0x2a6/0x2f0 kernel/trace/ring_buffer.c:5820
Modules linked in:
CPU: 1 PID: 13374 Comm: syz.5.1383 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:trace_rb_cpu_prepare+0x2a6/0x2f0 kernel/trace/ring_buffer.c:5820
Code: 48 0f ab 08 31 c0 48 83 c4 30 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 0a 24 fd ff 48 c7 c7 40 2f 2f 8a 8b 74 24 04 e8 1a 51 39 08 <0f> 0b b8 f4 ff ff ff eb d3 e8 ec 23 fd ff 0f 0b e9 83 fd ff ff e8
RSP: 0018:ffffc90002effac0 EFLAGS: 00010246
RAX: 3639278c22744e00 RBX: ffff88805ea8a810 RCX: 0000000000080000
RDX: ffffc9001330a000 RSI: 000000000003b133 RDI: 000000000003b134
RBP: ffff88807ddd8878 R08: ffff8880b9133d7f R09: 1ffff110172267af
R10: dffffc0000000000 R11: ffffed10172267b0 R12: 0000000000000000
R13: ffff888023073100 R14: ffff888023073100 R15: ffff88805ea8a8b0
FS:  00007faa3699d6c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5f8cc42d71 CR3: 000000005eb75000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 cpuhp_invoke_callback+0x481/0x7e0 kernel/cpu.c:201
 cpuhp_issue_call+0x3d3/0x760 kernel/cpu.c:-1
 __cpuhp_state_add_instance_cpuslocked+0x24b/0x6c0 kernel/cpu.c:2020
 __cpuhp_state_add_instance+0x21/0x30 kernel/cpu.c:2041
 cpuhp_state_add_instance include/linux/cpuhotplug.h:391 [inline]
 __ring_buffer_alloc+0x2d2/0x540 kernel/trace/ring_buffer.c:1844
 allocate_trace_buffer kernel/trace/trace.c:9249 [inline]
 allocate_trace_buffers+0x70/0x2c0 kernel/trace/trace.c:9271
 trace_array_create+0x2ac/0xc00 kernel/trace/trace.c:9427
 instance_mkdir+0xc8/0x120 kernel/trace/trace.c:9473
 tracefs_syscall_mkdir+0xb7/0x110 fs/tracefs/inode.c:87
 vfs_mkdir+0x386/0x570 fs/namei.c:4073
 do_mkdirat+0x1dd/0x5c0 fs/namei.c:4098
 __do_sys_mkdirat fs/namei.c:4113 [inline]
 __se_sys_mkdirat fs/namei.c:4111 [inline]
 __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7faa387450d9
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:00007faa3699d028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007faa389ccfa0 RCX: 00007faa387450d9
RDX: 00000000000001ff RSI: 0000200000000100 RDI: ffffffffffffff9c
RBP: 00007faa387dc024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007faa389cd038 R14: 00007faa389ccfa0 R15: 00007ffd91617228
 </TASK>

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/09 04:39 linux-5.15.y aabd761612db 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in trace_rb_cpu_prepare
2026/08/03 18:40 linux-5.15.y 6e2fd6534337 6b7c9f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in trace_rb_cpu_prepare
2026/08/03 06:21 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in trace_rb_cpu_prepare
2026/08/01 23:00 linux-5.15.y 6e2fd6534337 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING in trace_rb_cpu_prepare
* Struck through repros no longer work on HEAD.