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BUG: KCSAN: data-race in do_syslog / log_store

write to 0xffffffff89513200 of 8 bytes by task 17365 on cpu 0:
 log_store+0x7a2/0x7d0 kernel/printk/printk.c:672
 log_output kernel/printk/printk.c:1932 [inline]
 vprintk_store+0x5ba/0x700 kernel/printk/printk.c:1983
 vprintk_emit+0x114/0x4f0 kernel/printk/printk.c:2011
 dev_vprintk_emit+0x337/0x36f drivers/base/core.c:4129
 dev_printk_emit+0x6a/0x8c drivers/base/core.c:4140
 __dev_printk+0xfa/0x103 drivers/base/core.c:4152
 _dev_warn+0x76/0x96 drivers/base/core.c:4196
 hid_parser_main+0x5aa/0x6a0 drivers/hid/hid-core.c:630
 hid_open_report+0x36f/0x660 drivers/hid/hid-core.c:1253
 hid_parse include/linux/hid.h:1033 [inline]
 hid_generic_probe+0x3e/0x70 drivers/hid/hid-generic.c:63
 hid_device_probe+0x1e1/0x2e0 drivers/hid/hid-core.c:2274
 really_probe+0x4bc/0xb70 drivers/base/dd.c:553
 driver_probe_device+0xcc/0x120 drivers/base/dd.c:738
 __device_attach_driver+0x255/0x290 drivers/base/dd.c:844
 bus_for_each_drv+0xd8/0x140 drivers/base/bus.c:431
 __device_attach+0x1a0/0x290 drivers/base/dd.c:912
 device_initial_probe+0x16/0x20 drivers/base/dd.c:959
 bus_probe_device+0x7a/0x140 drivers/base/bus.c:491
 device_add+0x1178/0x12e0 drivers/base/core.c:2926
 hid_add_device+0x6ab/0x700 drivers/hid/hid-core.c:2430
 uhid_device_add_worker+0x27/0xb0 drivers/hid/uhid.c:62
 process_one_work+0x3e1/0x9a0 kernel/workqueue.c:2269
 worker_thread+0x665/0xbe0 kernel/workqueue.c:2415
 kthread+0x20d/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffffffff89513200 of 8 bytes by task 8356 on cpu 1:
 do_syslog+0x344/0x1480 kernel/printk/printk.c:1561
 kmsg_read+0x7a/0xa0 fs/proc/kmsg.c:40
 pde_read fs/proc/inode.c:306 [inline]
 proc_reg_read+0xde/0x1a0 fs/proc/inode.c:316
 vfs_read+0x16d/0x5e0 fs/read_write.c:479
 ksys_read+0xce/0x180 fs/read_write.c:615
 __do_sys_read fs/read_write.c:625 [inline]
 __se_sys_read fs/read_write.c:623 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:623
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8356 Comm: in:imklog Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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