==================================================================
BUG: KCSAN: data-race in wbc_detach_inode / wbc_detach_inode

write to 0xffff88821afad2de of 2 bytes by task 7842 on cpu 1:
 wbc_detach_inode+0x29f/0x540 fs/fs-writeback.c:706
 __filemap_fdatawrite_range+0x1c6/0x220 mm/filemap.c:422
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x2a/0x40 mm/filemap.c:456
 __sync_blockdev fs/block_dev.c:490 [inline]
 __sync_blockdev+0x84/0x90 fs/block_dev.c:485
 __sync_filesystem fs/sync.c:40 [inline]
 sync_filesystem+0x10b/0x1a0 fs/sync.c:64
 ovl_sync_fs+0x89/0xa0 fs/overlayfs/super.c:276
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem fs/sync.c:67 [inline]
 sync_filesystem+0x15d/0x1a0 fs/sync.c:48
 generic_shutdown_super+0x68/0x270 fs/super.c:448
 kill_anon_super+0x28/0x50 fs/super.c:1108
 deactivate_locked_super+0x5d/0xb0 fs/super.c:335
 deactivate_super fs/super.c:366 [inline]
 deactivate_super+0xca/0xe0 fs/super.c:362
 cleanup_mnt+0x27a/0x330 fs/namespace.c:1102
 __cleanup_mnt+0x1c/0x30 fs/namespace.c:1109
 task_work_run+0xf5/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88821afad2de of 2 bytes by task 7835 on cpu 0:
 wbc_detach_inode+0x75/0x540 fs/fs-writeback.c:638
 __filemap_fdatawrite_range+0x1c6/0x220 mm/filemap.c:422
 __filemap_fdatawrite mm/filemap.c:429 [inline]
 filemap_flush+0x2a/0x40 mm/filemap.c:456
 __sync_blockdev fs/block_dev.c:490 [inline]
 __sync_blockdev+0x84/0x90 fs/block_dev.c:485
 __sync_filesystem fs/sync.c:40 [inline]
 sync_filesystem+0x10b/0x1a0 fs/sync.c:64
 ovl_sync_fs+0x89/0xa0 fs/overlayfs/super.c:276
 __sync_filesystem fs/sync.c:39 [inline]
 sync_filesystem fs/sync.c:67 [inline]
 sync_filesystem+0x15d/0x1a0 fs/sync.c:48
 generic_shutdown_super+0x68/0x270 fs/super.c:448
 kill_anon_super+0x28/0x50 fs/super.c:1108
 deactivate_locked_super+0x5d/0xb0 fs/super.c:335
 deactivate_super fs/super.c:366 [inline]
 deactivate_super+0xca/0xe0 fs/super.c:362
 cleanup_mnt+0x27a/0x330 fs/namespace.c:1102
 __cleanup_mnt+0x1c/0x30 fs/namespace.c:1109
 task_work_run+0xf5/0x130 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x2ae/0x2c0 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:278 [inline]
 do_syscall_64+0x36e/0x390 arch/x86/entry/common.c:304
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 7835 Comm: syz-executor.3 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================