KCSAN: data-race in do_fcntl / vfs

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in do_fcntl / vfs_write fs				3	1098d	1134d	0/26	auto-closed as invalid on 2021/05/29 09:52

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BUG: KCSAN: data-race in do_fcntl / vfs_write

read-write to 0xffff888139d77c40 of 4 bytes by task 1814 on cpu 1:
 setfl fs/fcntl.c:80 [inline]
 do_fcntl+0xc72/0xd30 fs/fcntl.c:339
 __do_sys_fcntl fs/fcntl.c:453 [inline]
 __se_sys_fcntl+0xc6/0x180 fs/fcntl.c:438
 __x64_sys_fcntl+0x3f/0x50 fs/fcntl.c:438
 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+0x46/0xb0

read to 0xffff888139d77c40 of 4 bytes by task 1815 on cpu 0:
 iocb_flags include/linux/fs.h:3261 [inline]
 init_sync_kiocb include/linux/fs.h:2208 [inline]
 new_sync_write fs/read_write.c:500 [inline]
 vfs_write+0x3b2/0x890 fs/read_write.c:591
 ksys_write+0xe8/0x1a0 fs/read_write.c:644
 __do_sys_write fs/read_write.c:656 [inline]
 __se_sys_write fs/read_write.c:653 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:653
 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+0x46/0xb0

value changed: 0x00008001 -> 0x0004c801

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1815 Comm: syz-executor.0 Not tainted 5.19.0-rc5-syzkaller-00056-ge35e5b6f695d-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/29/2022
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