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BUG: KCSAN: data-race in ext4_mark_iloc_dirty / generic_update_time

write to 0xffff88811cd1f5e0 of 16 bytes by task 17332 on cpu 1:
 generic_update_time+0xc2/0x270 fs/inode.c:1673
 update_time+0x7d/0x90 fs/inode.c:1695
 file_update_time+0x205/0x2d0 fs/inode.c:1910
 file_modified fs/inode.c:1933 [inline]
 file_modified+0x60/0x80 fs/inode.c:1918
 ext4_dio_write_checks fs/ext4/file.c:430 [inline]
 ext4_dio_write_iter fs/ext4/file.c:494 [inline]
 ext4_file_write_iter+0xad5/0xd30 fs/ext4/file.c:640
 call_write_iter include/linux/fs.h:1907 [inline]
 do_iter_readv_writev+0x4a7/0x5d0 fs/read_write.c:694
 do_iter_write fs/read_write.c:999 [inline]
 do_iter_write+0x137/0x3a0 fs/read_write.c:980
 vfs_iter_write+0x56/0x80 fs/read_write.c:1040
 iter_file_splice_write+0x530/0x830 fs/splice.c:760
 do_splice_from fs/splice.c:863 [inline]
 direct_splice_actor+0x97/0xb0 fs/splice.c:1037
 splice_direct_to_actor+0x22f/0x540 fs/splice.c:992
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x380/0x800 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1568
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811cd1f5e8 of 8 bytes by task 233 on cpu 0:
 ext4_do_update_inode fs/ext4/inode.c:4983 [inline]
 ext4_mark_iloc_dirty+0x3e5/0x1580 fs/ext4/inode.c:5603
 ext4_mark_inode_dirty+0xe6/0x420 fs/ext4/inode.c:5796
 ext4_dirty_inode+0xad/0xd0 fs/ext4/inode.c:5827
 __mark_inode_dirty+0x5b7/0x940 fs/fs-writeback.c:2258
 mark_inode_dirty_sync include/linux/fs.h:2194 [inline]
 dquot_free_space include/linux/quotaops.h:385 [inline]
 dquot_free_block include/linux/quotaops.h:395 [inline]
 ext4_free_blocks+0x1350/0x1590 fs/ext4/mballoc.c:4957
 ext4_ext_try_to_merge_up fs/ext4/extents.c:1820 [inline]
 ext4_ext_try_to_merge+0x30b/0x360 fs/ext4/extents.c:1847
 ext4_convert_unwritten_extents_endio fs/ext4/extents.c:3710 [inline]
 ext4_ext_handle_unwritten_extents+0x291/0x18c0 fs/ext4/extents.c:3837
 ext4_ext_map_blocks+0xa7e/0x1fb0 fs/ext4/extents.c:4098
 ext4_map_blocks+0x230/0xcf0 fs/ext4/inode.c:621
 ext4_convert_unwritten_extents+0x18b/0x3b0 fs/ext4/extents.c:4729
 ext4_convert_unwritten_io_end_vec+0xe0/0x1b0 fs/ext4/extents.c:4764
 ext4_end_io_end fs/ext4/page-io.c:187 [inline]
 ext4_do_flush_completed_IO fs/ext4/page-io.c:260 [inline]
 ext4_end_io_rsv_work+0x2c2/0x400 fs/ext4/page-io.c:274
 process_one_work+0x424/0x930 kernel/workqueue.c:2268
 worker_thread+0x9a/0x7e0 kernel/workqueue.c:2414
 kthread+0x203/0x230 kernel/kthread.c:268
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 233 Comm: kworker/u4:3 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: ext4-rsv-conversion ext4_end_io_rsv_work
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