KCSAN: data-race in evict / inode_sync

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in evict / inode_sync_complete fs				1	1600d	1600d	0/26	auto-closed as invalid on 2020/03/02 13:52

==================================================================
BUG: KCSAN: data-race in evict / inode_sync_complete

write to 0xffff8880b11fc340 of 8 bytes by task 16632 on cpu 1:
 inode_sync_complete+0x34/0x70 fs/fs-writeback.c:1197
 writeback_sb_inodes+0x76d/0xa10 fs/fs-writeback.c:1744
 __writeback_inodes_wb+0xe9/0x1b0 fs/fs-writeback.c:1785
 wb_writeback+0x557/0x6a0 fs/fs-writeback.c:1894
 wb_check_background_flush fs/fs-writeback.c:1962 [inline]
 wb_do_writeback fs/fs-writeback.c:2050 [inline]
 wb_workfn+0x66b/0x970 fs/fs-writeback.c:2078
 process_one_work+0x424/0x930 kernel/workqueue.c:2264
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2410
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff8880b11fc340 of 8 bytes by task 7819 on cpu 0:
 evict+0x5c/0x3f0 fs/inode.c:558
 iput_final fs/inode.c:1571 [inline]
 iput+0x36a/0x4d0 fs/inode.c:1597
 dentry_unlink_inode+0x272/0x2e0 fs/dcache.c:374
 d_delete fs/dcache.c:2451 [inline]
 d_delete+0xca/0xe0 fs/dcache.c:2440
 vfs_rmdir fs/namei.c:3966 [inline]
 vfs_rmdir+0x2d3/0x2f0 fs/namei.c:3931
 do_rmdir+0x2e9/0x320 fs/namei.c:4014
 __do_sys_rmdir fs/namei.c:4032 [inline]
 __se_sys_rmdir fs/namei.c:4030 [inline]
 __x64_sys_rmdir+0x2c/0x40 fs/namei.c:4030
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7819 Comm: syz-executor.1 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================