EXT4-fs (loop1): Delayed block allocation failed for inode 18 at logical offset 0 with max blocks 1604 with error 28
==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff88e5c6d5 of 27 bytes by task 11913 on cpu 0:
 vsnprintf+0x2ce/0x890 lib/vsprintf.c:2826
 vscnprintf+0x41/0x90 lib/vsprintf.c:2939
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2216
 vprintk_store+0x599/0x860 kernel/printk/printk.c:2336
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 mnt_warn_timestamp_expiry+0x1c3/0x200 fs/namespace.c:3300
 do_new_mount_fc fs/namespace.c:3837 [inline]
 do_new_mount+0x2f6/0x680 fs/namespace.c:3904
 path_mount+0x4a4/0xb20 fs/namespace.c:4226
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4427
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4427
 x64_sys_call+0xd36/0x2fb0 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 0xffffffff88e5c6e8 of 8 bytes by task 11896 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:594 [inline]
 data_push_tail+0xfd/0x420 kernel/printk/printk_ringbuffer.c:679
 data_alloc+0xbf/0x2b0 kernel/printk/printk_ringbuffer.c:1054
 prb_reserve+0x808/0xaf0 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 __ext4_msg+0x18f/0x1a0 fs/ext4/super.c:981
 mpage_map_and_submit_extent fs/ext4/inode.c:2418 [inline]
 ext4_do_writepages+0x18f6/0x21c0 fs/ext4/inode.c:2863
 ext4_writepages+0x176/0x300 fs/ext4/inode.c:2953
 do_writepages+0x1c6/0x310 mm/page-writeback.c:2636
 filemap_fdatawrite_wbc mm/filemap.c:386 [inline]
 __filemap_fdatawrite_range mm/filemap.c:419 [inline]
 file_write_and_wait_range+0x156/0x2c0 mm/filemap.c:794
 generic_buffers_fsync_noflush+0x45/0x120 fs/buffer.c:609
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1ab/0x690 fs/ext4/fsync.c:147
 vfs_fsync_range+0x10a/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:3031 [inline]
 ext4_buffered_write_iter+0x34f/0x3c0 fs/ext4/file.c:305
 ext4_file_write_iter+0x383/0xf00 fs/ext4/file.c:-1
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x49d/0x8e0 fs/read_write.c:686
 ksys_write+0xda/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x2cdd/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:2
 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: 0x00000000fffff8a9 -> 0x3032206c69746e75

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11896 Comm: +}[@ Not tainted 6.16.0-rc3-syzkaller-00319-gded779017ad7 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================
EXT4-fs (loop1): This should not happen!! Data will be lost

EXT4-fs (loop1): Total free blocks count 0
EXT4-fs (loop1): Free/Dirty block details
EXT4-fs (loop1): free_blocks=0
EXT4-fs (loop1): dirty_blocks=1608
EXT4-fs (loop1): Block reservation details
EXT4-fs (loop1): i_reserved_data_blocks=1608