From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 27 Aug 2003 14:45:37 +0100 (BST) From: Hugh Dickins Subject: Re: Strange memory usage reporting In-Reply-To: <20030827095241.D639@nightmaster.csn.tu-chemnitz.de> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Sender: owner-linux-mm@kvack.org Return-Path: To: Ingo Oeser Cc: Jaroslav Kysela , "linux-kernel@vger.kernel.org" , linux-mm@kvack.org List-ID: 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org