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BUG: KCSAN: data-race in delete_from_page_cache_batch / file_write_and_wait_range

write to 0xffff88810904f418 of 8 bytes by task 918 on cpu 0:
 page_cache_delete_batch mm/filemap.c:342 [inline]
 delete_from_page_cache_batch+0x597/0x820 mm/filemap.c:360
 truncate_inode_pages_range+0x1d4/0xd60 mm/truncate.c:330
 truncate_inode_pages mm/truncate.c:428 [inline]
 truncate_pagecache+0x4f/0x70 mm/truncate.c:754
 ext4_setattr+0xae7/0xf60 fs/ext4/inode.c:5500
 notify_change+0x88f/0xa80 fs/attr.c:398
 do_truncate+0xe8/0x130 fs/open.c:64
 handle_truncate fs/namei.c:3020 [inline]
 do_open fs/namei.c:3371 [inline]
 path_openat+0x1b78/0x21b0 fs/namei.c:3500
 do_filp_open+0xd9/0x1f0 fs/namei.c:3527
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_creat fs/open.c:1277 [inline]
 __se_sys_creat fs/open.c:1271 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1271
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810904f418 of 8 bytes by task 898 on cpu 1:
 mapping_needs_writeback mm/filemap.c:632 [inline]
 file_write_and_wait_range+0x79/0x120 mm/filemap.c:762
 ext4_sync_file+0x105/0x6e0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2843 [inline]
 ext4_buffered_write_iter+0x38f/0x3e0 fs/ext4/file.c:277
 ext4_file_write_iter+0x48a/0x10b0 fs/ext4/file.c:502
 call_write_iter include/linux/fs.h:1977 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6f9/0x7e0 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+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 898 Comm: syz-executor.4 Tainted: G        W         5.12.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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