KCSAN: data-race in do_mmap / file_remove

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in do_mmap / file_remove_privs fs				1	1905d	1905d	0/28	closed as invalid on 2019/11/19 14:44

==================================================================
BUG: KCSAN: data-race in do_mmap / file_remove_privs

read-write to 0xffff88810c6f79ec of 4 bytes by task 5365 on cpu 0:
 inode_has_no_xattr include/linux/fs.h:3395 [inline]
 file_remove_privs+0x2ce/0x370 fs/inode.c:1945
 __generic_file_write_iter+0xda/0x330 mm/filemap.c:3404
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3490
 call_write_iter include/linux/fs.h:1903 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6d4/0x7c0 fs/read_write.c:605
 ksys_write+0xce/0x180 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x3e/0x50 fs/read_write.c:667
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810c6f79ec of 4 bytes by task 5366 on cpu 1:
 do_mmap+0x9e4/0xc90 mm/mmap.c:1516
 vm_mmap_pgoff+0xe5/0x170 mm/util.c:507
 ksys_mmap_pgoff+0x2a8/0x380 mm/mmap.c:1634
 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: 5366 Comm: syz-executor.0 Not tainted 5.10.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================