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BUG: KCSAN: data-race in data_push_tail / string

write to 0xffffffff870755a8 of 1 bytes by task 11478 on cpu 0:
 string_nocheck lib/vsprintf.c:647 [inline]
 string+0x17b/0x220 lib/vsprintf.c:725
 vsnprintf+0xb57/0xe80 lib/vsprintf.c:2782
 vscnprintf+0x3e/0x80 lib/vsprintf.c:2888
 printk_sprint kernel/printk/printk.c:2092 [inline]
 vprintk_store+0x5f2/0xb50 kernel/printk/printk.c:2206
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2282
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2292
 caif_disconnect_client+0x140/0x150 net/caif/cfcnfg.c:194
 caif_release+0xf8/0x240 net/caif/caif_socket.c:921
 __sock_release net/socket.c:650 [inline]
 sock_close+0x6c/0x150 net/socket.c:1365
 __fput+0x292/0x510 fs/file_table.c:320
 ____fput+0x11/0x20 fs/file_table.c:353
 task_work_run+0x8e/0x110 kernel/task_work.c:177
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x59a/0x16e0 kernel/exit.c:795
 __do_sys_exit kernel/exit.c:892 [inline]
 __se_sys_exit kernel/exit.c:890 [inline]
 __x64_sys_exit+0x1b/0x20 kernel/exit.c:890
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff870755a8 of 8 bytes by task 11479 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x10f/0x440 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x897/0xbd0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x51c/0xb50 kernel/printk/printk.c:2196
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2282
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x96 kernel/printk/printk.c:2292
 caif_disconnect_client+0x140/0x150 net/caif/cfcnfg.c:194
 caif_release+0xf8/0x240 net/caif/caif_socket.c:921
 __sock_release net/socket.c:650 [inline]
 sock_close+0x6c/0x150 net/socket.c:1365
 __fput+0x292/0x510 fs/file_table.c:320
 ____fput+0x11/0x20 fs/file_table.c:353
 task_work_run+0x8e/0x110 kernel/task_work.c:177
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x59a/0x16e0 kernel/exit.c:795
 __do_sys_exit kernel/exit.c:892 [inline]
 __se_sys_exit kernel/exit.c:890 [inline]
 __x64_sys_exit+0x1b/0x20 kernel/exit.c:890
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000ffffe071 -> 0x6e6f637369645f66

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11479 Comm: syz-executor.2 Tainted: G        W          5.19.0-syzkaller-13930-g7ebfc85e2cd7-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022
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