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BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff86a78df8 of 8 bytes by task 15032 on cpu 1:
 data_alloc+0x274/0x2e0 kernel/printk/printk_ringbuffer.c:1101
 prb_reserve+0x807/0xaf0 kernel/printk/printk_ringbuffer.c:1685
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299
 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2448
 __quota_error+0xf8/0x110 fs/quota/dquot.c:148
 qtree_write_dquot+0x289/0x300 fs/quota/quota_tree.c:453
 v2_write_dquot+0xda/0x140 fs/quota/quota_v2.c:372
 dquot_acquire+0x1c3/0x2b0 fs/quota/dquot.c:473
 ext4_acquire_dquot+0x15f/0x200 fs/ext4/super.c:6941
 dqget+0x535/0x8d0 fs/quota/dquot.c:980
 __dquot_initialize+0x20c/0x7c0 fs/quota/dquot.c:1508
 dquot_initialize+0x1a/0x30 fs/quota/dquot.c:1570
 ext4_evict_inode+0xd5/0xd90 fs/ext4/inode.c:192
 evict+0x2e3/0x550 fs/inode.c:810
 iput_final fs/inode.c:1914 [inline]
 iput+0x4ed/0x650 fs/inode.c:1966
 ext4_process_orphan+0x1a9/0x1c0 fs/ext4/orphan.c:356
 ext4_orphan_cleanup+0x6a8/0xa00 fs/ext4/orphan.c:470
 __ext4_fill_super fs/ext4/super.c:5617 [inline]
 ext4_fill_super+0x3483/0x3810 fs/ext4/super.c:5736
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691
 get_tree_bdev+0x1f/0x30 fs/super.c:1714
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5768
 vfs_get_tree+0x57/0x1d0 fs/super.c:1751
 fc_mount fs/namespace.c:1208 [inline]
 do_new_mount_fc fs/namespace.c:3651 [inline]
 do_new_mount+0x24d/0x660 fs/namespace.c:3727
 path_mount+0x4a5/0xb70 fs/namespace.c:4037
 do_mount fs/namespace.c:4050 [inline]
 __do_sys_mount fs/namespace.c:4238 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4215
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4215
 x64_sys_call+0x2b51/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 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 0xffffffff86a78df8 of 16 bytes by task 14996 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:479 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1892 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1940 [inline]
 _prb_read_valid+0x1bc/0x920 kernel/printk/printk_ringbuffer.c:2131
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2203
 __console_flush_and_unlock kernel/printk/printk.c:3277 [inline]
 console_unlock+0x164/0x2e0 kernel/printk/printk.c:3298
 class_console_lock_destructor include/linux/console.h:669 [inline]
 con_shutdown+0x4b/0x60 drivers/tty/vt/vt.c:3697
 release_tty+0x85/0x4f0 drivers/tty/tty_io.c:1580
 tty_release_struct+0x96/0xb0 drivers/tty/tty_io.c:1692
 tty_release+0x856/0xb10 drivers/tty/tty_io.c:1852
 __fput+0x29b/0x650 fs/file_table.c:468
 ____fput+0x1c/0x30 fs/file_table.c:496
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xed/0x110 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14996 Comm: syz.4.3347 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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