EXT4-fs error (device loop1): ext4_do_update_inode:5624: inode #15: comm syz.1.2178: corrupted inode contents
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff8686a230 of 8 bytes by task 3502 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
 devkmsg_emit+0x7f/0xb0 kernel/printk/printk.c:728
 devkmsg_write+0x1e3/0x2b0 kernel/printk/printk.c:791
 do_iter_readv_writev+0x4a1/0x540 fs/read_write.c:-1
 vfs_writev+0x2df/0x8b0 fs/read_write.c:1057
 do_writev+0xe7/0x210 fs/read_write.c:1103
 __do_sys_writev fs/read_write.c:1171 [inline]
 __se_sys_writev fs/read_write.c:1168 [inline]
 __x64_sys_writev+0x45/0x50 fs/read_write.c:1168
 x64_sys_call+0x1e9a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:21
 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 0xffffffff8686a230 of 16 bytes by task 11671 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
 desc_update_last_finalized kernel/printk/printk_ringbuffer.c:1531 [inline]
 prb_final_commit+0x136/0x1e0 kernel/printk/printk_ringbuffer.c:1800
 vprintk_store+0x741/0x860 kernel/printk/printk.c:2325
 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_inode+0x2ca/0x3f0 fs/ext4/super.c:853
 ext4_do_update_inode fs/ext4/inode.c:5624 [inline]
 ext4_mark_iloc_dirty+0x35e/0xda0 fs/ext4/inode.c:6274
 ext4_orphan_del+0x6db/0x710 fs/ext4/orphan.c:299
 ext4_evict_inode+0xaac/0xd90 fs/ext4/inode.c:292
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11671 Comm: syz.1.2178 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================
EXT4-fs error (device loop1) in ext4_orphan_del:301: Corrupt filesystem
EXT4-fs error (device loop1): ext4_do_update_inode:5624: inode #15: comm syz.1.2178: corrupted inode contents
EXT4-fs error (device loop1): ext4_evict_inode:302: inode #15: comm syz.1.2178: mark_inode_dirty error
EXT4-fs (loop1): 1 orphan inode deleted