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

write to 0xffff8880bb4bd338 of 8 bytes by task 10734 on cpu 1:
 i_size_write include/linux/fs.h:894 [inline]
 generic_write_end+0xd4/0x290 fs/buffer.c:2177
 ext4_da_write_end+0x162/0x690 fs/ext4/inode.c:3090
 generic_perform_write+0x1d7/0x320 mm/filemap.c:3313
 ext4_buffered_write_iter+0x14e/0x280 fs/ext4/file.c:270
 ext4_file_write_iter+0xf4/0xd30 fs/ext4/file.c:642
 call_write_iter include/linux/fs.h:1907 [inline]
 new_sync_write+0x303/0x400 fs/read_write.c:484
 __vfs_write+0x9e/0xb0 fs/read_write.c:497
 vfs_write fs/read_write.c:559 [inline]
 vfs_write+0x189/0x380 fs/read_write.c:543
 ksys_write+0xc5/0x1a0 fs/read_write.c:612
 __do_sys_write fs/read_write.c:624 [inline]
 __se_sys_write fs/read_write.c:621 [inline]
 __x64_sys_write+0x49/0x60 fs/read_write.c:621
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880bb4bd338 of 8 bytes by task 10735 on cpu 0:
 mpage_submit_page+0x78/0x190 fs/ext4/inode.c:2067
 mpage_map_and_submit_buffers+0x35d/0x610 fs/ext4/inode.c:2317
 mpage_map_and_submit_extent fs/ext4/inode.c:2456 [inline]
 ext4_writepages+0x11af/0x1e10 fs/ext4/inode.c:2770
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1bb/0x220 mm/filemap.c:421
 generic_fadvise+0x47b/0x490 mm/fadvise.c:115
 vfs_fadvise+0x8a/0x90 mm/fadvise.c:187
 ksys_fadvise64_64+0x5b/0xa0 mm/fadvise.c:201
 __do_sys_fadvise64 mm/fadvise.c:216 [inline]
 __se_sys_fadvise64 mm/fadvise.c:214 [inline]
 __x64_sys_fadvise64+0x5a/0x70 mm/fadvise.c:214
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10735 Comm: syz-executor.0 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================