audit: type=1326 audit(1919.796:140355): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=19395 comm="syz.1.15836" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fa87d21e929 code=0x7ffc0000
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff8686ec48 of 8 bytes by task 19393 on cpu 0:
 data_alloc+0x271/0x2b0 kernel/printk/printk_ringbuffer.c:1095
 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93
 loop_set_size+0x2e/0x70 drivers/block/loop.c:210
 loop_configure+0x8d3/0xa50 drivers/block/loop.c:1068
 lo_ioctl+0x559/0x15d0 drivers/block/loop.c:-1
 blkdev_ioctl+0x34f/0x440 block/ioctl.c:704
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x19a8/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8686ec48 of 16 bytes by task 29 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1874 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x1bc/0x920 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2185
 printk_get_next_message+0xc8/0x510 kernel/printk/printk.c:3005
 console_emit_next_record kernel/printk/printk.c:3092 [inline]
 console_flush_all+0x290/0x730 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xa1/0x330 kernel/printk/printk.c:3325
 vprintk_emit+0x388/0x650 kernel/printk/printk.c:2450
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 kauditd_printk_skb kernel/audit.c:546 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:581
 kauditd_send_queue+0x273/0x2c0 kernel/audit.c:766
 kauditd_thread+0x421/0x630 kernel/audit.c:890
 kthread+0x489/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 29 Comm: kauditd Not tainted 6.16.0-rc6-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================
audit: type=1326 audit(1919.796:140356): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=19395 comm="syz.1.15836" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fa87d21e929 code=0x7ffc0000
audit: type=1326 audit(1919.796:140357): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=19395 comm="syz.1.15836" exe="/root/syz-executor" sig=0 arch=c000003e syscall=61 compat=0 ip=0x7fa87d21e929 code=0x7ffc0000
audit: type=1326 audit(1919.796:140358): auid=4294967295 uid=0 gid=0 ses=4294967295 subj=root:sysadm_r:sysadm_t pid=19395 comm="syz.1.15836" exe="/root/syz-executor" sig=0 arch=c000003e syscall=202 compat=0 ip=0x7fa87d21e929 code=0x7ffc0000