==================================================================
BUG: KCSAN: data-race in delete_from_page_cache_batch / ext4_writepages

write to 0xffff88810c3db4d8 of 8 bytes by task 15044 on cpu 0:
 page_cache_delete_batch mm/filemap.c:340 [inline]
 delete_from_page_cache_batch+0x597/0x820 mm/filemap.c:358
 truncate_inode_pages_range+0x482/0x10e0 mm/truncate.c:366
 truncate_pagecache_range+0x80/0x90 mm/truncate.c:959
 ext4_punch_hole+0x368/0x9e0 fs/ext4/inode.c:4076
 ext4_fallocate+0xea/0x540 fs/ext4/extents.c:4655
 vfs_fallocate+0x471/0x6c0 fs/open.c:309
 ksys_fallocate fs/open.c:332 [inline]
 __do_sys_fallocate fs/open.c:340 [inline]
 __se_sys_fallocate fs/open.c:338 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:338
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88810c3db4d8 of 8 bytes by task 15037 on cpu 1:
 ext4_writepages+0x131/0x1e70 fs/ext4/inode.c:2669
 do_writepages+0x7b/0x150 mm/page-writeback.c:2352
 __filemap_fdatawrite_range+0x19d/0x1d0 mm/filemap.c:422
 file_write_and_wait_range+0x9f/0x120 mm/filemap.c:761
 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:2737 [inline]
 ext4_buffered_write_iter+0x38f/0x3e0 fs/ext4/file.c:278
 ext4_file_write_iter+0x47a/0x1060 fs/ext4/file.c:503
 call_write_iter include/linux/fs.h:1901 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x6f0/0x7e0 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+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15037 Comm: syz-executor.1 Not tainted 5.11.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================