[v6.6] WARNING in trace_rb_cpu_prepare

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a1153c0deb44 Linux 6.6.147
git tree: linux-6.6.y
console output: https://syzkaller.appspot.com/x/log.txt?x=103ccdb9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f0bc3d90c30838b5
dashboard link: https://syzkaller.appspot.com/bug?extid=59657eaf8add48294429
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/9f646bfa1b52/disk-a1153c0d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a2aec2e8f0fd/vmlinux-a1153c0d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a7abe1f87405/bzImage-a1153c0d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+59657e...@syzkaller.appspotmail.com

------------[ cut here ]------------
failed to allocate ring buffer on CPU 1
WARNING: CPU: 0 PID: 9268 at kernel/trace/ring_buffer.c:5864 trace_rb_cpu_prepare+0x2fa/0x330 kernel/trace/ring_buffer.c:5863
Modules linked in:
CPU: 0 PID: 9268 Comm: syz.4.1091 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:trace_rb_cpu_prepare+0x2fa/0x330 kernel/trace/ring_buffer.c:5863
Code: 00 f0 48 0f ab 2b 31 c0 48 83 c4 38 5b 41 5c 41 5d 41 5e 41 5f 5d c3 e8 64 04 fd ff 48 c7 c7 a0 ee ce 8a 89 de e8 66 d4 c6 ff <0f> 0b b8 f4 ff ff ff eb d5 e8 48 04 fd ff e9 32 ff ff ff e8 3e 04
RSP: 0018:ffffc90004ddfab8 EFLAGS: 00010246
RAX: 92c3ed053b7e9200 RBX: 0000000000000001 RCX: 0000000000080000
RDX: ffffc90018dcd000 RSI: 000000000007ffff RDI: 0000000000080000
RBP: 0000000000000001 R08: ffff8880b8e28c53 R09: 1ffff110171c518a
R10: dffffc0000000000 R11: ffffed10171c518b R12: 0000000000000000
R13: ffff888064dce108 R14: ffff88801b28e810 R15: ffff88801b28e8b0
FS: 00007fd6ef1316c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fadef75da08 CR3: 0000000030895000 CR4: 00000000003506f0
Call Trace:
<TASK>
cpuhp_invoke_callback+0x481/0x7e0 kernel/cpu.c:205
cpuhp_issue_call+0x3ed/0x740 kernel/cpu.c:-1
__cpuhp_state_add_instance_cpuslocked+0x22a/0x570 kernel/cpu.c:2460
__cpuhp_state_add_instance+0x25/0x40 kernel/cpu.c:2481
cpuhp_state_add_instance include/linux/cpuhotplug.h:396 [inline]
__ring_buffer_alloc+0x30e/0x550 kernel/trace/ring_buffer.c:1866
allocate_trace_buffer kernel/trace/trace.c:9282 [inline]
allocate_trace_buffers+0x70/0x290 kernel/trace/trace.c:9314
trace_array_create_systems+0x311/0xc70 kernel/trace/trace.c:9460
trace_array_create kernel/trace/trace.c:9497 [inline]
instance_mkdir+0xd1/0x130 kernel/trace/trace.c:9512
tracefs_syscall_mkdir+0x128/0x1a0 fs/tracefs/inode.c:139
vfs_mkdir+0x2a5/0x470 fs/namei.c:4125
do_mkdirat+0x1dc/0x450 fs/namei.c:4148
__do_sys_mkdirat fs/namei.c:4163 [inline]
__se_sys_mkdirat fs/namei.c:4161 [inline]
__x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4161
do_syscall_x64 arch/x86/entry/common.c:46 [inline]
do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fd6ee19e019
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:00007fd6ef131028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fd6ee425fa0 RCX: 00007fd6ee19e019
RDX: 00000000000001ff RSI: 0000200000000140 RDI: ffffffffffffff9c
RBP: 00007fd6ee23500c R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fd6ee426038 R14: 00007fd6ee425fa0 R15: 00007fffe7ec14f8
</TASK>


---
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[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6e2fd6534337 Linux 5.15.213
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17a08db9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=f161cbc9aef65db0
dashboard link: https://syzkaller.appspot.com/bug?extid=b8c64aaf011042278a71

compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:

disk image: https://storage.googleapis.com/syzbot-assets/d7b46606b13d/disk-6e2fd653.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/da120fdeb081/vmlinux-6e2fd653.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3c2643457e3f/bzImage-6e2fd653.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:

Reported-by: syzbot+b8c64a...@syzkaller.appspotmail.com

------------[ cut here ]------------
failed to allocate ring buffer on CPU 1

WARNING: CPU: 0 PID: 5248 at kernel/trace/ring_buffer.c:5821 trace_rb_cpu_prepare+0x2a6/0x2f0 kernel/trace/ring_buffer.c:5820
Modules linked in:
CPU: 0 PID: 5248 Comm: syz.2.225 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:ffffc9000320fac0 EFLAGS: 00010246
RAX: 93f106198b8cbe00 RBX: ffff88805e1f1410 RCX: 0000000000080000
RDX: ffffc9000f68f000 RSI: 000000000001adbf RDI: 000000000001adc0
RBP: ffff8880777f1078 R08: ffff8880b9033d7f R09: 1ffff110172067af
R10: dffffc0000000000 R11: ffffed10172067b0 R12: 0000000000000000
R13: ffff888018983108 R14: ffff888018983108 R15: ffff88805e1f14b0
FS: 00007f25d3a976c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 00005559a8866950 CR3: 0000000023655000 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: 0033:0x7f25d5860019

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:00007f25d3a97028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f25d5ae8090 RCX: 00007f25d5860019
RDX: 00000000000001ff RSI: 0000200000000200 RDI: ffffffffffffff9c
RBP: 00007f25d58f700c R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 00007f25d5ae8128 R14: 00007f25d5ae8090 R15: 00007ffdb77de598