syzbot

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BUG: KCSAN: data-race in __uart_start / __update_runtime_status

write to 0xffff888100e709c4 of 4 bytes by task 3773 on cpu 0:
 __update_runtime_status+0xef/0x1d0 drivers/base/power/runtime.c:98
 rpm_resume+0x9f1/0xd00 drivers/base/power/runtime.c:921
 pm_runtime_work+0xe4/0x130 drivers/base/power/runtime.c:979
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0x465/0x990 kernel/workqueue.c:3335
 worker_thread+0x526/0x730 kernel/workqueue.c:3416
 kthread+0x1d1/0x210 kernel/kthread.c:388
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243

read to 0xffff888100e709c4 of 4 bytes by task 4488 on cpu 1:
 pm_runtime_active include/linux/pm_runtime.h:164 [inline]
 __uart_start+0x1ab/0x270 drivers/tty/serial/serial_core.c:159
 uart_write+0x348/0x450 drivers/tty/serial/serial_core.c:615
 do_output_char+0x491/0x500 drivers/tty/n_tty.c:428
 process_output drivers/tty/n_tty.c:494 [inline]
 n_tty_write+0x8cc/0xb90 drivers/tty/n_tty.c:2390
 iterate_tty_write drivers/tty/tty_io.c:1021 [inline]
 file_tty_write+0x386/0x690 drivers/tty/tty_io.c:1096
 tty_write+0x28/0x30 drivers/tty/tty_io.c:1117
 call_write_iter include/linux/fs.h:2108 [inline]
 iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4488 Comm: syz-executor.2 Tainted: G        W          6.9.0-rc2-syzkaller-00002-g026e680b0a08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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