BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff86f6b340 of 1 bytes by task 11316 on cpu 0:
 vsnprintf+0xdd0/0xe20
 vscnprintf+0x42/0x80 lib/vsprintf.c:2923
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2128
 vprintk_store+0x56f/0x800 kernel/printk/printk.c:2242
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 __ext4_msg+0x18a/0x1a0 fs/ext4/super.c:937
 ext4_check_feature_compatibility+0xde/0x610 fs/ext4/super.c:4658
 __ext4_fill_super fs/ext4/super.c:5277 [inline]
 ext4_fill_super+0x20f6/0x38b0 fs/ext4/super.c:5696
 get_tree_bdev+0x2b4/0x3b0 fs/super.c:1318
 ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5728
 vfs_get_tree+0x51/0x190 fs/super.c:1519
 do_new_mount+0x203/0x660 fs/namespace.c:3335
 path_mount+0x496/0xb30 fs/namespace.c:3662
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86f6b340 of 8 bytes by task 11313 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 __ext4_warning+0x12c/0x140 fs/ext4/super.c:962
 ext4_multi_mount_protect+0x147/0x5e0 fs/ext4/mmp.c:292
 __ext4_fill_super fs/ext4/super.c:5357 [inline]
 ext4_fill_super+0x2803/0x38b0 fs/ext4/super.c:5696
 get_tree_bdev+0x2b4/0x3b0 fs/super.c:1318
 ext4_get_tree+0x1c/0x20 fs/ext4/super.c:5728
 vfs_get_tree+0x51/0x190 fs/super.c:1519
 do_new_mount+0x203/0x660 fs/namespace.c:3335
 path_mount+0x496/0xb30 fs/namespace.c:3662
 do_mount fs/namespace.c:3675 [inline]
 __do_sys_mount fs/namespace.c:3884 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3861
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3861
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x000000010001f744 -> 0x000000010001f700

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11313 Comm: syz-executor.5 Not tainted 6.5.0-rc7-syzkaller-00164-g382d4cd18475 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
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