Re: [RFC][PATCH 6/8] mm: handle_speculative_fault()

[Christoph Lameter]

On Thu, 7 Jan 2010, Linus Torvalds wrote:

> +	if (brk < cur_brk)
> +		goto slow_case;
> +	if (brk == cur_brk)
> +		goto out;
> +
> +	vma = ok_to_extend_brk(mm, cur_brk, brk);
> +	if (!vma)
> +		goto slow_case;
> +
> +	spin_lock(&mm->page_table_lock);


page_table_lock used to serialize multiple fast brks?

CONFIG_SPLIT_PTLOCK implies that code will not use this lock in fault
handling. So no serialization with faults.

Also the current code assumes vm_end and so on to be stable if mmap_sem is
held. F.e. find_vma() from do_fault is now running while vm_end may be changing
under it.


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