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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff8689d660 of 88 bytes by task 25219 on cpu 0:
 prb_reserve+0x695/0xaf0 kernel/printk/printk_ringbuffer.c:1651
 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
 __ext4_error+0x248/0x320 fs/ext4/super.c:822
 ext4_orphan_get+0x189/0x430 fs/ext4/ialloc.c:1395
 ext4_orphan_cleanup+0x5fa/0xa00 fs/ext4/orphan.c:463
 __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:1698
 get_tree_bdev+0x1f/0x30 fs/super.c:1721
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5768
 vfs_get_tree+0x57/0x1d0 fs/super.c:1758
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3642 [inline]
 do_new_mount+0x24d/0x660 fs/namespace.c:3718
 path_mount+0x4a5/0xb70 fs/namespace.c:4028
 do_mount fs/namespace.c:4041 [inline]
 __do_sys_mount fs/namespace.c:4229 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4206
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4206
 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 0xffffffff8689d660 of 8 bytes by task 25225 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:483 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1975 [inline]
 _prb_read_valid+0x383/0x920 kernel/printk/printk_ringbuffer.c:2132
 prb_read_valid_info+0x66/0x90 kernel/printk/printk_ringbuffer.c:2238
 find_first_fitting_seq+0x1b1/0x320 kernel/printk/printk.c:1562
 syslog_print_all+0x111/0x3a0 kernel/printk/printk.c:1694
 do_syslog+0x2fd/0x7e0 kernel/printk/printk.c:1772
 __do_sys_syslog kernel/printk/printk.c:1850 [inline]
 __se_sys_syslog kernel/printk/printk.c:1848 [inline]
 __x64_sys_syslog+0x41/0x50 kernel/printk/printk.c:1848
 x64_sys_call+0x2f45/0x3000 arch/x86/include/generated/asm/syscalls_64.h:104
 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

value changed: 0x00000000000020f2 -> 0x00000000000040f2

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 25225 Comm: syz.0.8050 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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