On Mon, 16 Feb 2004, Rajesh Venkatasubramanian wrote:

This path fixes a NULL pointer dereference bug in mremap. In
move_one_page we need to re-check the src because an allocation
for the dst page table can drop page_table_lock, and somebody
else can invalidate the src.

Ugly, but yes. The "!page_table_present(mm, new_addr))" code just before
the "alloc_one_pte_map()" should already have done this, but while the 
page tables themselves are safe due to us holding the mm semaphore, the 
pte entry itself at "src" is not.

I hate that code, and your patch makes it even uglier. This code could do 
with a real clean-up, but for now I think your patch will do.

Thanks,

		Linus
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