syzbot

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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff85cb5d40 of 8 bytes by task 8794 on cpu 1:
 prb_reserve+0x733/0xbd0
 vprintk_store+0x51c/0xb50 kernel/printk/printk.c:2196
 vprintk_emit+0xcc/0x430 kernel/printk/printk.c:2252
 dev_vprintk_emit+0x1c9/0x1ed drivers/base/core.c:4736
 dev_printk_emit+0x7e/0xa2 drivers/base/core.c:4747
 __dev_printk+0xfa/0x110 drivers/base/core.c:4759
 _dev_info+0x9d/0xc1 drivers/base/core.c:4805
 attach_store+0x628/0x6d0 drivers/usb/usbip/vhci_sysfs.c:438
 dev_attr_store+0x40/0x60 drivers/base/core.c:2211
 sysfs_kf_write+0xa6/0xc0 fs/sysfs/file.c:136
 kernfs_fop_write_iter+0x1d3/0x2c0 fs/kernfs/file.c:354
 call_write_iter include/linux/fs.h:2187 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x468/0x760 fs/read_write.c:584
 ksys_write+0xe8/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:646
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff85cb5d40 of 8 bytes by task 1425 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1846 [inline]
 _prb_read_valid+0x2e3/0x950 kernel/printk/printk_ringbuffer.c:1892
 prb_read_valid+0x39/0x60 kernel/printk/printk_ringbuffer.c:1940
 syslog_print+0x4b2/0x580 kernel/printk/printk.c:1546
 do_syslog+0x741/0x7e0 kernel/printk/printk.c:1682
 __do_sys_syslog kernel/printk/printk.c:1774 [inline]
 __se_sys_syslog kernel/printk/printk.c:1772 [inline]
 __x64_sys_syslog+0x3f/0x50 kernel/printk/printk.c:1772
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000002820 -> 0x0000000000004820

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1425 Comm: klogd Not tainted 6.0.0-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/22/2022
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