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BUG: KCSAN: data-race in ext4_mark_iloc_dirty / ext4_writepages

read to 0xffff8881260e9a50 of 8 bytes by task 11354 on cpu 1:
 ext4_do_update_inode fs/ext4/inode.c:5280 [inline]
 ext4_mark_iloc_dirty+0x810/0x1580 fs/ext4/inode.c:5876
 ext4_mark_inode_dirty+0xe9/0x420 fs/ext4/inode.c:6055
 ext4_dirty_inode+0x86/0xb0 fs/ext4/inode.c:6086
 __mark_inode_dirty+0x5d4/0x940 fs/fs-writeback.c:2258
 mark_inode_dirty include/linux/fs.h:2165 [inline]
 generic_write_end+0x1b7/0x1f0 fs/buffer.c:2159
 ext4_da_write_end+0x158/0x620 fs/ext4/inode.c:3189
 generic_perform_write+0x1d3/0x320 mm/filemap.c:3316
 __generic_file_write_iter+0x251/0x380 mm/filemap.c:3434
 ext4_file_write_iter+0x1bd/0xa00 fs/ext4/file.c:268
 call_write_iter include/linux/fs.h:1895 [inline]
 new_sync_write+0x388/0x4a0 fs/read_write.c:483
 __vfs_write+0xb1/0xc0 fs/read_write.c:496
 vfs_write fs/read_write.c:558 [inline]
 vfs_write+0x18a/0x390 fs/read_write.c:542
 ksys_write+0xd5/0x1b0 fs/read_write.c:611
 __do_sys_write fs/read_write.c:623 [inline]
 __se_sys_write fs/read_write.c:620 [inline]
 __x64_sys_write+0x4c/0x60 fs/read_write.c:620
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8881260e9a50 of 8 bytes by task 11361 on cpu 0:
 mpage_map_and_submit_extent fs/ext4/inode.c:2576 [inline]
 ext4_writepages+0x1785/0x2300 fs/ext4/inode.c:2869
 do_writepages+0x6b/0x170 mm/page-writeback.c:2344
 __filemap_fdatawrite_range+0x1c5/0x230 mm/filemap.c:421
 filemap_write_and_wait_range mm/filemap.c:681 [inline]
 filemap_write_and_wait_range+0xb1/0x150 mm/filemap.c:675
 ext4_punch_hole+0x175/0xab0 fs/ext4/inode.c:4270
 ext4_fallocate+0x2bc/0x13d0 fs/ext4/extents.c:4889
 vfs_fallocate+0x3be/0x650 fs/open.c:309
 ksys_fallocate+0x61/0xa0 fs/open.c:332
 __do_sys_fallocate fs/open.c:340 [inline]
 __se_sys_fallocate fs/open.c:338 [inline]
 __x64_sys_fallocate+0x5e/0x80 fs/open.c:338
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11361 Comm: syz-executor.4 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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