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BUG: KCSAN: data-race in copy_page_to_iter / ext4_mb_mark_diskspace_used

write to 0xffff8881495c1000 of 8 bytes by task 9457 on cpu 1:
 instrument_write include/linux/instrumented.h:42 [inline]
 __set_bit include/asm-generic/bitops/instrumented-non-atomic.h:27 [inline]
 __set_bit_le include/asm-generic/bitops/le.h:100 [inline]
 mb_set_bit fs/ext4/mballoc.c:467 [inline]
 ext4_set_bits fs/ext4/mballoc.c:1701 [inline]
 ext4_mb_mark_diskspace_used+0x5db/0xca0 fs/ext4/mballoc.c:3775
 ext4_mb_new_blocks+0xab3/0x1f90 fs/ext4/mballoc.c:5532
 ext4_alloc_branch fs/ext4/indirect.c:333 [inline]
 ext4_ind_map_blocks+0xaab/0x1620 fs/ext4/indirect.c:626
 ext4_map_blocks+0x6d2/0xef0 fs/ext4/inode.c:640
 _ext4_get_block+0xf6/0x290 fs/ext4/inode.c:794
 ext4_get_block+0x35/0x40 fs/ext4/inode.c:811
 __block_write_begin_int+0x4a2/0x1060 fs/buffer.c:2031
 __block_write_begin+0x2b/0x40 fs/buffer.c:2081
 ext4_write_begin+0x41b/0xcc0 fs/ext4/ext4_jbd2.h:498
 ext4_da_write_begin+0x20e/0x820 fs/ext4/inode.c:2960
 generic_perform_write+0x196/0x3a0 mm/filemap.c:3660
 ext4_buffered_write_iter+0x2f2/0x3f0 fs/ext4/file.c:269
 ext4_file_write_iter+0x2e7/0x11d0 fs/ext4/file.c:519
 call_write_iter include/linux/fs.h:2114 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x69d/0x770 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+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881495c1000 of 1024 bytes by task 9464 on cpu 0:
 instrument_copy_to_user include/linux/instrumented.h:119 [inline]
 copyout lib/iov_iter.c:189 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:261 [inline]
 copy_page_to_iter+0x320/0x860 lib/iov_iter.c:973
 filemap_read+0xf06/0x1230 mm/filemap.c:2605
 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2701
 blkdev_read_iter+0xb9/0xf0 fs/block_dev.c:1732
 call_read_iter include/linux/fs.h:2108 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x565/0x5d0 fs/read_write.c:496
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 9464 Comm: systemd-udevd Not tainted 5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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