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

write to 0xffff888125873618 of 8 bytes by task 2731 on cpu 0:
 i_size_write include/linux/fs.h:913 [inline]
 generic_write_end+0x96/0x180 fs/buffer.c:2186
 ext4_da_write_end+0x4de/0x630 fs/ext4/inode.c:3059
 generic_perform_write+0x261/0x400 mm/filemap.c:3767
 ext4_buffered_write_iter+0x25b/0x380 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x1200
 call_write_iter include/linux/fs.h:2162 [inline]
 do_iter_readv_writev+0x2de/0x380 fs/read_write.c:725
 do_iter_write+0x192/0x5c0 fs/read_write.c:851
 vfs_iter_write+0x4c/0x70 fs/read_write.c:892
 iter_file_splice_write+0x43a/0x790 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888125873618 of 8 bytes by task 43 on cpu 1:
 i_size_read include/linux/fs.h:891 [inline]
 mpage_submit_page fs/ext4/inode.c:2089 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2343 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2482 [inline]
 ext4_writepages+0x10b6/0x1e80 fs/ext4/inode.c:2795
 do_writepages+0x1cb/0x330 mm/page-writeback.c:2364
 __writeback_single_inode+0x80/0x4d0 fs/fs-writeback.c:1616
 writeback_sb_inodes+0x677/0xdf0 fs/fs-writeback.c:1881
 wb_writeback+0x26b/0x650 fs/fs-writeback.c:2054
 wb_do_writeback+0x101/0x560 fs/fs-writeback.c:2197
 wb_workfn+0xc8/0x440 fs/fs-writeback.c:2238
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

value changed: 0x000000000021d000 -> 0x000000000021e000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 43 Comm: kworker/u4:2 Not tainted 5.16.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
==================================================================