EXT4-fs warning (device loop7): dx_probe:846: Directory (ino: 2) htree depth 0x0002 exceedsupported value
EXT4-fs warning (device loop7): dx_probe:849: Enable large directory feature to access it
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86a7f6a0 of 8 bytes by task 10619 on cpu 0:
 data_alloc+0x31c/0x390 kernel/printk/printk_ringbuffer.c:1130
 prb_reserve+0x8d7/0xae0 kernel/printk/printk_ringbuffer.c:1724
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2302
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2402
 devkmsg_emit+0x7f/0xb0 kernel/printk/printk.c:731
 devkmsg_write+0x1e2/0x2b0 kernel/printk/printk.c:794
 do_iter_readv_writev+0x4fd/0x5a0 fs/read_write.c:-1
 vfs_writev+0x2e1/0x900 fs/read_write.c:1057
 do_writev+0xe9/0x210 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+0x1ba5/0x3000 arch/x86/include/generated/asm/syscalls_64.h:21
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86a7f6a0 of 8 bytes by task 13025 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:792 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:938 [inline]
 prb_reserve+0x207/0xae0 kernel/printk/printk_ringbuffer.c:1674
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2302
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 __ext4_warning_inode+0x184/0x1a0 fs/ext4/super.c:1032
 dx_probe+0x924/0x990 fs/ext4/namei.c:933
 ext4_dx_find_entry fs/ext4/namei.c:1721 [inline]
 __ext4_find_entry+0x35a/0xdf0 fs/ext4/namei.c:1561
 ext4_lookup_entry fs/ext4/namei.c:1703 [inline]
 ext4_lookup+0xcd/0x3a0 fs/ext4/namei.c:1769
 lookup_open fs/namei.c:4422 [inline]
 open_last_lookups fs/namei.c:4549 [inline]
 path_openat+0xee1/0x23c0 fs/namei.c:4793
 do_filp_open+0x15d/0x280 fs/namei.c:4823
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_creat fs/open.c:1514 [inline]
 __se_sys_creat fs/open.c:1508 [inline]
 __x64_sys_creat+0x65/0x90 fs/open.c:1508
 x64_sys_call+0x2f1c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:86
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000151098 -> 0x00000000001fc658

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13025 Comm: syz.7.11929 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
==================================================================
EXT4-fs warning (device loop7): dx_probe:934: inode #2: comm syz.7.11929: Corrupt directory, running e2fsck is recommended