EXT4-fs error (device loop6): ext4_do_update_inode:5632: inode #2: comm syz.6.7637: corrupted inode contents
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff868dc4a0 of 88 bytes by task 26804 on cpu 0:
 prb_reserve+0x695/0xaf0 kernel/printk/printk_ringbuffer.c:1651
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299
 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
 set_capacity_and_notify+0x14c/0x1f0 block/genhd.c:93
 loop_set_size+0x2e/0x70 drivers/block/loop.c:220
 loop_configure+0x828/0x9c0 drivers/block/loop.c:1081
 lo_ioctl+0x1e1/0x12b0 drivers/block/loop.c:1536
 blkdev_ioctl+0x356/0x440 block/ioctl.c:705
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1816/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
 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 0xffffffff868dc4a0 of 8 bytes by task 26795 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:483 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1975 [inline]
 _prb_read_valid+0x383/0x920 kernel/printk/printk_ringbuffer.c:2132
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2203
 __console_flush_and_unlock kernel/printk/printk.c:3277 [inline]
 console_unlock+0x164/0x2e0 kernel/printk/printk.c:3298
 vprintk_emit+0x3b5/0x580 kernel/printk/printk.c:2423
 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:5632 [inline]
 ext4_mark_iloc_dirty+0x35e/0xda0 fs/ext4/inode.c:6282
 __ext4_mark_inode_dirty+0x2e2/0x3f0 fs/ext4/inode.c:6488
 __ext4_ext_dirty+0xdb/0x1f0 fs/ext4/extents.c:206
 ext4_ext_insert_extent+0x13db/0x29b0 fs/ext4/extents.c:2192
 ext4_ext_map_blocks+0x10b8/0x38a0 fs/ext4/extents.c:4404
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x5ee/0xd00 fs/ext4/inode.c:811
 ext4_getblk+0x114/0x510 fs/ext4/inode.c:978
 ext4_bread+0x28/0x110 fs/ext4/inode.c:1041
 ext4_append+0x16e/0x2b0 fs/ext4/namei.c:83
 ext4_add_entry+0x1053/0x1c60 fs/ext4/namei.c:2442
 ext4_add_nondir+0x4e/0x180 fs/ext4/namei.c:2784
 ext4_create+0x1ff/0x2f0 fs/ext4/namei.c:2830
 lookup_open fs/namei.c:3796 [inline]
 open_last_lookups fs/namei.c:3895 [inline]
 path_openat+0x1105/0x2170 fs/namei.c:4131
 do_filp_open+0x109/0x230 fs/namei.c:4161
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_creat fs/open.c:1530 [inline]
 __se_sys_creat fs/open.c:1524 [inline]
 __x64_sys_creat+0x65/0x90 fs/open.c:1524
 x64_sys_call+0x2da3/0x3000 arch/x86/include/generated/asm/syscalls_64.h:86
 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: 0x0000000000002c62 -> 0x0000000000004c62

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 26795 Comm: syz.6.7637 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================
EXT4-fs error (device loop6): __ext4_ext_dirty:206: inode #2: comm syz.6.7637: mark_inode_dirty error
syz.6.7637 (26795) used greatest stack depth: 8952 bytes left