High kernel CPU usage when copying files

[Rutkov Denis]

Dear linux kernel hackers, I need help hunting a very annoying bug. 

I'm using Xubuntu 9.04 (kernel 2.6.28-11-42) on a P4@xxxxxx PC with 512MB RAM and two IDE drives (ext4). 

Whenever I copy files I got very high CPU usage from kernel. I tested this with ext3, ext4 and fat32 file systems. To trace the problem I installed oprofile and debug kernel image. I ran the profiler during file copying and saw that there are many calls to copy_to_user_ll and copy_from_user_ll functions. So I have two questions:

1. Is this normal I get so many of those function calls?

2. What can I do to further trace this bug?
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