On Tue, 2005-08-09 at 15:50 +0100, Hugh Dickins wrote: > On Tue, 9 Aug 2005, Benjamin Herrenschmidt wrote: > > > > > But you don't mind if they are refcounted, do you? > > > Just so long as they start out from 1 so never get freed. > > > > Well, a refcounting bug would let them be freed and kaboom ... That's > > why a "PG_not_your_ram_dammit" bit would be useful. It could at least > > BUG_ON when refcount reaches 0 :) > > Okay, great, let's give every struct page two refcounts, > so if one of them goes wrong, the other one will save us.
You are abusing here :) - We already have a refcount - We have a field where putting a flag isn't that much of a problem - It can be difficult to get page refcounting right when dealing with such things, really. In that case, we basically have an _easy_ way to trigger a useful BUG() in the page free path when it's a page that should never be returned to the pool. Since the "PG_not_in_ram" or whatever we call it flag might be used by swsusp or others, I suppose it could be useful. However, I agree that if the end result is to have drivers just change "PG_reserved" to "PG_not_in_ram" and still be bogus, then we might just go all the way & drop the flag completely, only relying on the VMA flags. Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
