>The case where you have removed the flush is not always the
>ZERO_PAGE,
Hmm, really? Maybe I am misunderstanding what the "if (from ==
ZERO_PAGE(to))" check actually does.
You understand it just fine, however you believe that copy_cow_page is
actually passed ZERO_PAGE in the instance where you removed the flush.
Your change is to remove the flush from this stretch of code:
linux/mm/memory.c:~line 823
copy_cow_page(old_page,new_page);
flush_page_to_ram(old_page);
flush_page_to_ram(new_page);
What is the invariant which makes you believe that
"old_page == ZERO_PAGE(new_page)" at this spot each
and every time?
Later,
David S. Miller
davem@redhat.com
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