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BUG: KCSAN: data-race in copy_page_to_iter / ext4_update_super

write to 0xffff88816219c430 of 4 bytes by task 5975 on cpu 0:
 __ext4_update_tstamp fs/ext4/super.c:412 [inline]
 ext4_update_super+0xff/0x740 fs/ext4/super.c:5502
 ext4_commit_super+0xf5/0x270 fs/ext4/super.c:5567
 flush_stashed_error_work+0x117/0x130 fs/ext4/super.c:727
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2275
 worker_thread+0x636/0xae0 kernel/workqueue.c:2421
 kthread+0x1d0/0x1f0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff88816219c400 of 1024 bytes by task 31539 on cpu 1:
 instrument_copy_to_user include/linux/instrumented.h:119 [inline]
 copyout lib/iov_iter.c:188 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:260 [inline]
 copy_page_to_iter+0x320/0x860 lib/iov_iter.c:979
 filemap_read+0xf06/0x1230 mm/filemap.c:2580
 generic_file_read_iter+0x84/0x3e0 mm/filemap.c:2676
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1720
 call_read_iter include/linux/fs.h:2110 [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: 1 PID: 31539 Comm: systemd-udevd Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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