loop3: detected capacity change from 0 to 512
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve_in_last

write to 0xffffffff86e7cde8 of 8 bytes by task 2981 on cpu 1:
 data_realloc kernel/printk/printk_ringbuffer.c:1228 [inline]
 prb_reserve_in_last+0x9c7/0xae0 kernel/printk/printk_ringbuffer.c:1498
 vprintk_store+0x45b/0x910 kernel/printk/printk.c:2328
 vprintk_emit+0x1a4/0x610 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
 disk_unlock_native_capacity block/partitions/core.c:522 [inline]
 blk_add_partition block/partitions/core.c:545 [inline]
 blk_add_partitions block/partitions/core.c:635 [inline]
 bdev_disk_changed+0xacb/0xe20 block/partitions/core.c:695
 blkdev_get_whole+0x1e8/0x2c0 block/bdev.c:793
 bdev_open+0x279/0x7d0 block/bdev.c:1002
 bdev_file_open_by_dev+0x1cc/0x230 block/bdev.c:1104
 disk_scan_partitions+0x149/0x1b0 block/genhd.c:387
 blkdev_common_ioctl+0x120d/0x2060 block/ioctl.c:713
 blkdev_ioctl+0x31f/0x460 block/ioctl.c:792
 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+0x239d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:17
 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

read to 0xffffffff86e7cde0 of 16 bytes by task 10910 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1934 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1982 [inline]
 _prb_read_valid+0x183/0x930 kernel/printk/printk_ringbuffer.c:2173
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2245
 printk_get_next_message+0xea/0x550 kernel/printk/printk.c:3052
 console_emit_next_record kernel/printk/printk.c:3137 [inline]
 console_flush_one_record kernel/printk/printk.c:3268 [inline]
 console_flush_all+0x2bc/0x6d0 kernel/printk/printk.c:3350
 __console_flush_and_unlock kernel/printk/printk.c:3380 [inline]
 console_unlock+0xa1/0x280 kernel/printk/printk.c:3420
 vprintk_emit+0x3e5/0x610 kernel/printk/printk.c:2479
 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
 set_capacity_and_notify+0x1d5/0x230 block/genhd.c:93
 loop_set_size+0x2e/0x70 drivers/block/loop.c:221
 loop_configure+0x826/0x9c0 drivers/block/loop.c:1101
 lo_ioctl+0x1e3/0x1430 drivers/block/loop.c:1556
 blkdev_ioctl+0x387/0x460 block/ioctl.c:798
 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+0x239d/0x2550 arch/x86/include/generated/asm/syscalls_64.h:17
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10910 Comm: syz.3.3560 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
==================================================================
EXT4-fs: Ignoring removed nobh option
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #3: comm syz.3.3560: corrupted inode contents
loop3: lost file I/O error report for ino 3 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_dirty_inode:6731: inode #3: comm syz.3.3560: mark_inode_dirty error
loop3: lost file I/O error report for ino 3 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #3: comm syz.3.3560: corrupted inode contents
loop3: lost file I/O error report for ino 3 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): __ext4_ext_dirty:207: inode #3: comm syz.3.3560: mark_inode_dirty error
loop3: lost file I/O error report for ino 3 type 5 pos 0x0 len 0x0 error -117
Quota error (device loop3): write_blk: dquota write failed
Quota error (device loop3): qtree_write_dquot: Error -117 occurred while creating quota
EXT4-fs error (device loop3): ext4_acquire_dquot:7069: comm syz.3.3560: Failed to acquire dquot type 0
loop3: lost filesystem error report for type 5 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #16: comm syz.3.3560: corrupted inode contents
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_dirty_inode:6731: inode #16: comm syz.3.3560: mark_inode_dirty error
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #16: comm syz.3.3560: corrupted inode contents
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): __ext4_ext_dirty:207: inode #16: comm syz.3.3560: mark_inode_dirty error
loop3: lost file I/O error report for ino 16 type 5 pos 0x0 len 0x0 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #16: comm syz.3.3560: corrupted inode contents
EXT4-fs error (device loop3) in ext4_orphan_del:304: Corrupt filesystem
loop3: lost filesystem error report for type 5 error -117
EXT4-fs error (device loop3): ext4_do_update_inode:5801: inode #16: comm syz.3.3560: corrupted inode contents
EXT4-fs error (device loop3): ext4_truncate:4721: inode #16: comm syz.3.3560: mark_inode_dirty error
EXT4-fs error (device loop3) in ext4_process_orphan:346: Corrupt filesystem
loop3: lost filesystem error report for type 5 error -117
EXT4-fs (loop3): 1 truncate cleaned up
EXT4-fs (loop3): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.