syzbot


WARNING in ring_buffer_map_get_reader

Status: upstream: reported on 2025/11/05 19:56
Subsystems: trace
[Documentation on labels]
Reported-by: syzbot+92a3745cea5ec6360309@syzkaller.appspotmail.com
Fix commit: aa997d2d2a0b ring-buffer: Do not warn in ring_buffer_map_get_reader() when reader catches up
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-snapshot-upstream-root ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce], missing on: [ci-qemu-native-arm64-kvm ci-qemu2-riscv64 ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-arm64 ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci2-upstream-usb]
First crash: 8d13h, last: 8d13h
Discussions (2)
Title Replies (including bot) Last reply
[for-linus][PATCH 1/3] ring-buffer: Do not warn in ring_buffer_map_get_reader() when reader catches up 1 (1) 2025/11/07 13:07
[syzbot] [trace?] WARNING in ring_buffer_map_get_reader 0 (1) 2025/11/05 19:56

Sample crash report:
------------[ cut here ]------------
WARNING: CPU: 0 PID: 9655 at kernel/trace/ring_buffer.c:7348 ring_buffer_map_get_reader+0x676/0x8e0 kernel/trace/ring_buffer.c:7348
Modules linked in:
CPU: 0 UID: 0 PID: 9655 Comm: syz.2.14601 Tainted: G     U  W I  L XTNJ syzkaller #0 PREEMPT(full) 
Tainted: [U]=USER, [W]=WARN, [I]=FIRMWARE_WORKAROUND, [L]=SOFTLOCKUP, [X]=AUX, [T]=RANDSTRUCT, [N]=TEST, [J]=FWCTL
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:ring_buffer_map_get_reader+0x676/0x8e0 kernel/trace/ring_buffer.c:7348
Code: 02 00 00 49 8b 0c 24 8b 74 24 3c 4c 89 f2 48 c7 c7 a0 09 93 8b e8 7a 1d da ff e9 e2 fe ff ff 4c 8b 74 24 58 e8 7b b0 fb ff 90 <0f> 0b 90 e8 72 b0 fb ff 48 89 df 31 db e8 88 f6 fd ff 48 8b 74 24
RSP: 0018:ffffc900053b7db0 EFLAGS: 00010083
RAX: 0000000000000773 RBX: ffff88813ff28800 RCX: ffffc900130af000
RDX: 0000000000080000 RSI: ffffffff81c0bcd5 RDI: 0000000000000007
RBP: dffffc0000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: ffff88813ff288b0 R12: ffff88813ff288b0
R13: 0000000000000000 R14: ffff88813ff28818 R15: ffff88813ff14c00
FS:  00007f5e1e7046c0(0000) GS:ffff888124a10000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32a12ff8 CR3: 0000000021b1c000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 tracing_buffers_ioctl+0x2bd/0x370 kernel/trace/trace.c:8717
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl fs/ioctl.c:583 [inline]
 __x64_sys_ioctl+0x18e/0x210 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f5e1d78efc9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5e1e704038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5e1d9e5fa0 RCX: 00007f5e1d78efc9
RDX: 0000000000000000 RSI: 0000000000005220 RDI: 0000000000000004
RBP: 00007f5e1d811f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5e1d9e6038 R14: 00007f5e1d9e5fa0 R15: 00007ffcaeda0b48
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/01 19:54 upstream 691d401c7e0e 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci-qemu-gce-upstream-auto WARNING in ring_buffer_map_get_reader
* Struck through repros no longer work on HEAD.