vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(7)
vhci_hcd vhci_hcd.0: devid(0) speed(1) speed_str(low-speed)
vhci_hcd vhci_hcd.0: Device attached
==================================================================
BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff868c5bb0 of 88 bytes by task 16032 on cpu 1:
 prb_reserve+0x696/0xaf0 kernel/printk/printk_ringbuffer.c:1635
 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_grp_locked_error+0x599/0x780 fs/ext4/super.c:1054
 ext4_mb_generate_buddy+0x243/0x2c0 fs/ext4/mballoc.c:1217
 ext4_mb_init_cache+0x82b/0xb70 fs/ext4/mballoc.c:1406
 ext4_mb_init_group+0x25b/0x3f0 fs/ext4/mballoc.c:1543
 ext4_mb_load_buddy_gfp+0x72a/0x790 fs/ext4/mballoc.c:1613
 ext4_mb_load_buddy fs/ext4/mballoc.c:1733 [inline]
 ext4_mb_find_by_goal+0x10b/0x720 fs/ext4/mballoc.c:2346
 ext4_mb_regular_allocator+0x135/0x2300 fs/ext4/mballoc.c:2818
 ext4_mb_new_blocks+0x800/0x2050 fs/ext4/mballoc.c:6215
 ext4_ext_map_blocks+0xff5/0x38a0 fs/ext4/extents.c:4383
 ext4_map_create_blocks fs/ext4/inode.c:609 [inline]
 ext4_map_blocks+0x61c/0xd70 fs/ext4/inode.c:813
 mpage_map_one_extent fs/ext4/inode.c:2348 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2401 [inline]
 ext4_do_writepages+0x12d5/0x21c0 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
 do_iter_readv_writev+0x421/0x4c0 fs/read_write.c:-1
 vfs_writev+0x2df/0x8b0 fs/read_write.c:1057
 do_pwritev fs/read_write.c:1153 [inline]
 __do_sys_pwritev2 fs/read_write.c:1211 [inline]
 __se_sys_pwritev2+0xfc/0x1c0 fs/read_write.c:1202
 __x64_sys_pwritev2+0x67/0x80 fs/read_write.c:1202
 x64_sys_call+0x1cea/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:329
 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 0xffffffff868c5bb0 of 8 bytes by task 16053 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1957 [inline]
 _prb_read_valid+0x383/0x920 kernel/printk/printk_ringbuffer.c:2114
 desc_update_last_finalized kernel/printk/printk_ringbuffer.c:1515 [inline]
 desc_make_final+0xe2/0x190 kernel/printk/printk_ringbuffer.c:1570
 prb_reserve+0x7c4/0xaf0 kernel/printk/printk_ringbuffer.c:1667
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2326
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 dev_vprintk_emit+0x242/0x2a0 drivers/base/core.c:4917
 dev_printk_emit+0x84/0xb0 drivers/base/core.c:4928
 __dev_printk+0xf3/0x110 drivers/base/core.c:4940
 _dev_info+0x9b/0xd0 drivers/base/core.c:4986
 attach_store+0x5f8/0x680 drivers/usb/usbip/vhci_sysfs.c:439
 dev_attr_store+0x4a/0x70 drivers/base/core.c:2440
 sysfs_kf_write+0xfb/0x120 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x1be/0x2d0 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x4a0/0x8e0 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: 0x0000000000002816 -> 0x0000000000004816

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16053 Comm: syz.0.3950 Not tainted 6.16.0-rc7-syzkaller-00127-g302f88ff3584 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
==================================================================