Messages in this thread | | | Date | Fri, 2 Apr 2004 03:09:00 +0200 | From | Andrea Arcangeli <> | Subject | Re: Properly stop kernel threads on aic7xxx |
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On Thu, Apr 01, 2004 at 05:04:03PM -0800, Andrew Morton wrote: > Andrea Arcangeli <andrea@suse.de> wrote: > > > > I'm also unsure why _all_ multipage allocations really need this > > compound thing setup and why can't the owner of the page take care of > > the refcounting itself by always using the head page. I may actually > > add a GFP bitflag asking for a multipage but w/o a compound setup. There > > are million ways to fix this, none of which is obvious. > > For direct-io into higher-order pages. When doing direct-io into a hugetlb > page we need to make sure that get_user_pages() pins the correct pageframe.
we do the same in bigpages 2.4 just fine with a basic math on the page_t knowing it's 2M naturally aligned, very easy to find the head page on vmas with VM_HUGETLBFS.
> Possibly we need to turn it on regardless of CONFIG_HUGETLBPAGE for people > who want to do direct-io or PEEKTEXT/POKETEXT into mmapped soundcard > buffers, for example. Perhaps there's a race which could permit direct-io > to write to a freed page via this route.. > > Davem had some reason why he might want to turn on the compound logic > permanently - related to TCP access to/from higher-order pages, I think.
currently it's turned on only with HUGTLBFS=y though. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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