Re: [PATCH v4 3.0-rc2-tip 2/22] 2: uprobes: Breakground page replacement.

Oleg Nesterov
2011-06-14T14:29:23Z

On 06/14, Peter Zijlstra wrote:
>
> On Mon, 2011-06-13 at 19:00 +0200, Oleg Nesterov wrote:
> >
> > Also. This is called under down_read(mmap_sem), can't we race with
> > access_process_vm() modifying the same memory?
>
> Shouldn't matter COW and similar things are serialized using the pte
> lock.

Yes, but afaics this doesn't matter. Suppose that write_opcode() is
called when access_process_vm() does copy_to_user_page(). We can cow
the page before memcpy() completes.

Oleg.