==================================================================
BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff88baabde of 1 bytes by task 11201 on cpu 0:
 number+0x7d0/0xa90 lib/vsprintf.c:564
 vsnprintf+0xa44/0xe30 lib/vsprintf.c:2869
 vscnprintf+0x42/0x90 lib/vsprintf.c:2909
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2197
 vprintk_store+0x570/0x810 kernel/printk/printk.c:2311
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2383
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2422
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:68
 _printk+0x7a/0xa0 kernel/printk/printk.c:2432
 __ext4_error_inode+0x30b/0x400 fs/ext4/super.c:849
 __ext4_check_dir_entry+0x478/0x500 fs/ext4/dir.c:117
 ext4_search_dir fs/ext4/namei.c:1504 [inline]
 search_dirblock fs/ext4/namei.c:1300 [inline]
 __ext4_find_entry+0xf76/0x1090 fs/ext4/namei.c:1658
 ext4_lookup_entry fs/ext4/namei.c:1729 [inline]
 ext4_lookup+0xba/0x390 fs/ext4/namei.c:1797
 __lookup_slow+0x184/0x250 fs/namei.c:1732
 lookup_slow+0x3c/0x60 fs/namei.c:1749
 walk_component+0x1f5/0x230 fs/namei.c:2053
 lookup_last fs/namei.c:2556 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2580
 filename_lookup+0x127/0x300 fs/namei.c:2609
 do_linkat+0xc5/0x600 fs/namei.c:4789
 __do_sys_link fs/namei.c:4843 [inline]
 __se_sys_link fs/namei.c:4841 [inline]
 __x64_sys_link+0x58/0x70 fs/namei.c:4841
 x64_sys_call+0x22a2/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:87
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff88baabd8 of 8 bytes by task 11173 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2301
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2383
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2422
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:68
 _printk+0x7a/0xa0 kernel/printk/printk.c:2432
 __ext4_error_file+0x31c/0x410 fs/ext4/super.c:887
 __ext4_check_dir_entry+0x436/0x500 fs/ext4/dir.c:111
 ext4_readdir+0xba1/0x1ba0 fs/ext4/dir.c:259
 iterate_dir+0x11d/0x310 fs/readdir.c:108
 __do_sys_getdents fs/readdir.c:324 [inline]
 __se_sys_getdents+0x88/0x1a0 fs/readdir.c:309
 __x64_sys_getdents+0x43/0x50 fs/readdir.c:309
 x64_sys_call+0x2bbb/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:79
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000fffffe15 -> 0x203a3631206b636f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11173 Comm: syz.1.1761 Tainted: G        W          6.12.0-rc2-syzkaller-00291-g09f6b0c8904b #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================
EXT4-fs error (device loop1): ext4_readdir:261: inode #2: block 20: comm syz.1.1761: path /115/file1: bad entry in directory: rec_len is smaller than minimal - offset=0, inode=0, rec_len=0, size=1024 fake=0
EXT4-fs error (device loop1): ext4_readdir:261: inode #2: block 21: comm syz.1.1761: path /115/file1: bad entry in directory: rec_len is smaller than minimal - offset=0, inode=0, rec_len=0, size=1024 fake=0