lo speed is unknown, defaulting to 1000
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff8686ebd8 of 8 bytes by task 12409 on cpu 1:
 data_alloc+0x27d/0x2b0 kernel/printk/printk_ringbuffer.c:1096
 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
 chnl_net_open+0x2a9/0x560 net/caif/chnl_net.c:260
 __dev_open+0x2d2/0x530 net/core/dev.c:1682
 __dev_change_flags+0x163/0x400 net/core/dev.c:9549
 netif_change_flags+0x5a/0xd0 net/core/dev.c:9612
 dev_change_flags+0xce/0x180 net/core/dev_api.c:68
 dev_ifsioc+0x44b/0xaa0 net/core/dev_ioctl.c:579
 dev_ioctl+0x70a/0x960 net/core/dev_ioctl.c:838
 sock_do_ioctl+0x197/0x220 net/socket.c:1252
 sock_ioctl+0x41b/0x610 net/socket.c:1359
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:584
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
 x64_sys_call+0x1816/0x2ff0 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 0xffffffff8686ebd8 of 8 bytes by task 3387 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline]
 prb_reserve+0x221/0xaf0 kernel/printk/printk_ringbuffer.c:1619
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4914
 dev_printk_emit+0x84/0xb0 drivers/base/core.c:4925
 __dev_printk+0xf3/0x110 drivers/base/core.c:4937
 _dev_warn+0x9b/0xd0 drivers/base/core.c:4981
 ib_cache_update+0x63a/0x700 drivers/infiniband/core/cache.c:1461
 ib_cache_event_task+0x7f/0xf0 drivers/infiniband/core/cache.c:1539
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
 worker_thread+0x582/0x770 kernel/workqueue.c:3400
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0xfffffffffffd3ad8 -> 0x000000000007da20

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3387 Comm: kworker/0:4 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Workqueue: infiniband ib_cache_event_task
==================================================================
infiniband syz2: ib_query_port failed (-19)