Messages in this thread | | | Date | Wed, 27 Aug 2003 14:45:37 +0100 (BST) | From | Hugh Dickins <> | Subject | Re: Strange memory usage reporting |
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On Wed, 27 Aug 2003, Ingo Oeser wrote: > On Tue, Aug 26, 2003 at 06:03:14PM +0100, Hugh Dickins wrote: > > Which is the driver involved? Though it's not wrong to give do_no_page > > a Reserved page, beware of the the page->count accounting: while it's > > Reserved, get_page or page_cache_get raises the count, but put_page > > or page_cache_release does not decrement it - very easy to end up > > with the page never freed. > > Why is this so asymetric? I would understand ignoring these pages > in the freeing logic, but why exclude them also from refcounting?
I don't think there's a _good_ reason, it just evolved that way.
The real answer is to get rid of PageReserved completely, which I'll embark on again in 2.7 (I did start a couple of times in 2.5, but each time it was too late).
There was a halfway-house suggestion in 2.5 about three months ago, inspired (as usual) by Reserved page problems in AIO's get_user_pages, to do as you suggest: submit them to normal refcounting. I don't know what became of that, I didn't have much time to get involved.
Hugh
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