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

write to 0xffffffff895fa1e0 of 1 bytes by task 28 on cpu 1:
 string_nocheck lib/vsprintf.c:654 [inline]
 string+0x165/0x220 lib/vsprintf.c:732
 vsnprintf+0x543/0x8c0 lib/vsprintf.c:2948
 vscnprintf+0x41/0x90 lib/vsprintf.c:3017
 printk_sprint+0x30/0x2b0 kernel/printk/printk.c:2222
 vprintk_store+0x57f/0x910 kernel/printk/printk.c:2364
 vprintk_emit+0x1a4/0x580 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 kauditd_printk_skb kernel/audit.c:588 [inline]
 kauditd_hold_skb+0x1b1/0x1c0 kernel/audit.c:623
 kauditd_send_queue+0x275/0x2d0 kernel/audit.c:808
 kauditd_thread+0x439/0x660 kernel/audit.c:932
 kthread+0x223/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffffffff895fa1e0 of 8 bytes by task 8787 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:607 [inline]
 data_push_tail+0x104/0x440 kernel/printk/printk_ringbuffer.c:692
 data_alloc+0x111/0x380 kernel/printk/printk_ringbuffer.c:1088
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1725
 vprintk_store+0x54e/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x580 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __ext4_error+0x225/0x2e0 fs/ext4/super.c:840
 ext4_validate_block_bitmap+0x586/0x5c0 fs/ext4/balloc.c:-1
 ext4_read_block_bitmap_nowait+0x420/0x660 fs/ext4/balloc.c:561
 ext4_mb_prefetch+0x191/0x260 fs/ext4/mballoc.c:2876
 ext4_mb_might_prefetch fs/ext4/mballoc.c:2917 [inline]
 ext4_mb_scan_group+0x177/0xf50 fs/ext4/mballoc.c:2962
 ext4_mb_scan_groups_linear fs/ext4/mballoc.c:1174 [inline]
 ext4_mb_scan_groups fs/ext4/mballoc.c:1206 [inline]
 ext4_mb_regular_allocator+0x5bc/0x1540 fs/ext4/mballoc.c:3061
 ext4_mb_new_blocks+0x7e8/0x1fa0 fs/ext4/mballoc.c:6309
 ext4_alloc_branch fs/ext4/indirect.c:340 [inline]
 ext4_ind_map_blocks+0xc2e/0x15e0 fs/ext4/indirect.c:652
 ext4_map_create_blocks+0x8a/0x390 fs/ext4/inode.c:699
 ext4_map_blocks+0x8a9/0xff0 fs/ext4/inode.c:942
 mpage_map_one_extent fs/ext4/inode.c:2505 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2601 [inline]
 ext4_do_writepages+0xf6d/0x2740 fs/ext4/inode.c:3077
 ext4_writepages+0x18c/0x300 fs/ext4/inode.c:3171
 do_writepages+0x1b9/0x300 mm/page-writeback.c:2560
 filemap_writeback mm/filemap.c:387 [inline]
 filemap_fdatawrite_range mm/filemap.c:412 [inline]
 file_write_and_wait_range+0x186/0x300 mm/filemap.c:786
 ext4_sync_file+0x114/0x5c0 fs/ext4/fsync.c:145
 vfs_fsync_range+0xc5/0xe0 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2693 [inline]
 ext4_buffered_write_iter+0x518/0x580 fs/ext4/file.c:378
 ext4_file_write_iter+0x36e/0x1020 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57a/0x990 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x3fffffffffffedea -> 0x3732363133333937

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 8787 Comm: syz.0.1687 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
==================================================================
EXT4-fs (loop0): Delayed block allocation failed for inode 13 at logical offset 2 with max blocks 10 with error 28
EXT4-fs (loop0): This should not happen!! Data will be lost

EXT4-fs (loop0): Total free blocks count 0
EXT4-fs (loop0): Free/Dirty block details
EXT4-fs (loop0): free_blocks=0
EXT4-fs (loop0): dirty_blocks=10
EXT4-fs (loop0): Block reservation details
EXT4-fs (loop0): i_reserved_data_blocks=10
EXT4-fs error (device loop0): ext4_find_dest_de:2052: inode #2: block 13: comm syz.0.1687: bad entry in directory: directory entry overrun - offset=76, inode=0, rec_len=1024, size=1024 fake=0
syz.0.1687 (8787) used greatest stack depth: 7728 bytes left