[moderation] [trace?] KCSAN: data-race in rb_move_tail / rb_watermark_hit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bd5f485f3f02 Merge tag 'soc-arm-7.3' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ee9679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=885647b8fd38e8cc
dashboard link: https://syzkaller.appspot.com/bug?extid=2339ee1713be6fa74d75
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
CC: [linux-...@vger.kernel.org linux-tra...@vger.kernel.org mathieu....@efficios.com mhir...@kernel.org ros...@goodmis.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8d8487052771/disk-bd5f485f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/73cdf4daa507/vmlinux-bd5f485f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bac756d0971e/bzImage-bd5f485f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2339ee...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in rb_move_tail / rb_watermark_hit

read-write to 0xffff88810007a858 of 8 bytes by task 8088 on cpu 0:
rb_inc_page kernel/trace/ring_buffer.c:1389 [inline]
rb_set_commit_to_write kernel/trace/ring_buffer.c:4194 [inline]
rb_end_commit kernel/trace/ring_buffer.c:4239 [inline]
rb_move_tail+0x556/0xba0 kernel/trace/ring_buffer.c:3926
__rb_reserve_next+0x485/0x6c0 kernel/trace/ring_buffer.c:4772
rb_reserve_next_event kernel/trace/ring_buffer.c:4928 [inline]
ring_buffer_lock_reserve+0x65c/0x810 kernel/trace/ring_buffer.c:4987
__trace_buffer_lock_reserve kernel/trace/trace.h:1676 [inline]
trace_event_buffer_lock_reserve+0x14a/0x300 kernel/trace/trace.c:1924
trace_event_buffer_reserve+0x120/0x180 kernel/trace/trace_events.c:688
do_trace_event_raw_event_sys_enter include/trace/events/syscalls.h:18 [inline]
trace_event_raw_event_sys_enter+0x6b/0x1f0 include/trace/events/syscalls.h:18
__do_trace_sys_enter include/trace/events/syscalls.h:18 [inline]
trace_sys_enter include/trace/events/syscalls.h:18 [inline]
trace_syscall_enter+0xc4/0x110 kernel/entry/syscall-common.c:13
syscall_trace_enter include/linux/entry-common.h:103 [inline]
syscall_enter_from_user_mode_work include/linux/entry-common.h:140 [inline]
do_syscall_64+0x295/0x360 arch/x86/entry/syscall_64.c:81
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810007a858 of 8 bytes by task 8087 on cpu 1:
rb_watermark_hit+0xb9/0x270 kernel/trace/ring_buffer.c:901
ring_buffer_poll_wait+0x1b4/0x200 kernel/trace/ring_buffer.c:1059
trace_poll kernel/trace/trace.c:5323 [inline]
tracing_poll_pipe+0xf7/0x120 kernel/trace/trace.c:5332
vfs_poll include/linux/poll.h:82 [inline]
io_file_supports_nowait io_uring/rw.c:47 [inline]
__io_read+0x305/0xbd0 io_uring/rw.c:943
io_read+0x4a/0x1b0 io_uring/rw.c:1036
__io_issue_sqe+0xfd/0x2e0 io_uring/io_uring.c:1395
io_issue_sqe+0x1e7/0xb80 io_uring/io_uring.c:1418
io_queue_sqe io_uring/io_uring.c:1649 [inline]
io_req_task_submit+0x46/0xa0 io_uring/io_uring.c:1058
tctx_task_work_run+0x3a9/0x500 io_uring/tw.c:96
tctx_task_work+0x3f/0x60 io_uring/tw.c:133
task_work_run+0x130/0x1a0 kernel/task_work.c:233
get_signal+0xdc1/0xf10 kernel/signal.c:2818
arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x15d/0x8c0 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
do_syscall_64+0x212/0x360 arch/x86/entry/syscall_64.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88811b770cc0 -> 0xffff88811b8b4500

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 8087 Comm: syz.2.1421 Not tainted syzkaller #0 PREEMPT(lazy)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================


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