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BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86a99440 of 8 bytes by task 837 on cpu 1:
 data_alloc+0x27e/0x2b0 kernel/printk/printk_ringbuffer.c:1085
 prb_reserve+0x8da/0xbb0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x3e9/0x9b0 kernel/printk/printk.c:2005
 vprintk_emit+0xca/0x360 kernel/printk/printk.c:2057
 dev_vprintk_emit+0x1c6/0x1ea drivers/base/core.c:4283
 dev_printk_emit+0x6a/0x8c drivers/base/core.c:4294
 __dev_printk+0xfa/0x103 drivers/base/core.c:4306
 _dev_warn+0x76/0x96 drivers/base/core.c:4350
 usb_parse_configuration drivers/usb/core/config.c:691 [inline]
 usb_get_configuration+0x7ae/0x29f0 drivers/usb/core/config.c:944
 usb_enumerate_device drivers/usb/core/hub.c:2388 [inline]
 usb_new_device+0xb3/0xc80 drivers/usb/core/hub.c:2524
 hub_port_connect drivers/usb/core/hub.c:5223 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
 port_event drivers/usb/core/hub.c:5509 [inline]
 hub_event+0x1d25/0x2b60 drivers/usb/core/hub.c:5591
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 process_scheduled_works kernel/workqueue.c:2337 [inline]
 worker_thread+0x7ef/0xb90 kernel/workqueue.c:2423
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffffffff86a99440 of 8 bytes by task 4498 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:477 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:771 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:917 [inline]
 prb_reserve+0x20c/0xbb0 kernel/printk/printk_ringbuffer.c:1499
 vprintk_store+0x3e9/0x9b0 kernel/printk/printk.c:2005
 vprintk_emit+0xca/0x360 kernel/printk/printk.c:2057
 dev_vprintk_emit+0x1c6/0x1ea drivers/base/core.c:4283
 dev_printk_emit+0x6a/0x8c drivers/base/core.c:4294
 __dev_printk+0xfa/0x103 drivers/base/core.c:4306
 _dev_info+0x76/0x96 drivers/base/core.c:4352
 hub_port_init+0x7bc/0x1890 drivers/usb/core/hub.c:4647
 hub_port_connect drivers/usb/core/hub.c:5155 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5363 [inline]
 port_event drivers/usb/core/hub.c:5509 [inline]
 hub_event+0x1a33/0x2b60 drivers/usb/core/hub.c:5591
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 process_scheduled_works kernel/workqueue.c:2337 [inline]
 worker_thread+0x7ef/0xb90 kernel/workqueue.c:2423
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4498 Comm: kworker/0:8 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: usb_hub_wq hub_event
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