Re: [PATCH][RFC][0/4] InfiniBand userspace verbs implementation

From: Greg KH
Date: Sun Apr 24 2005 - 16:28:50 EST

On Sun, Apr 24, 2005 at 09:23:48AM -0500, Timur Tabi wrote:
> Andrew Morton wrote:
> >If your theory is correct then it should be able to demonstrate this
> >problem without any special hardware at all: pin some user memory, then
> >generate memory pressure then check the contents of those pinned pages.
> I tried that, but I couldn't get it to fail. But that was a while ago, and
> I've learned a few things since then, so I'll try again.
> >But if, for the DMA transfer, you're using the array of page*'s which were
> >originally obtained from get_user_pages() then it's rather hard to see how
> >the kernel could alter the page's contents.
> >
> >Then again, if mlock() fixes it then something's up. Very odd.
> With mlock(), we don't need to use get_user_pages() at all. Arjan tells me
> the only time an mlocked page can move is with hot (un)plug of memory, but
> that isn't supported on the systems that we support.

You don't "support" i386 or ia64 or x86-64 or ppc64 systems? What
hardware do you support? And what about the fact that you are aiming to
get this code into mainline, right? If not, why are you asking here?


greg k-h
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