From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [RFC][patch 0/2] mm: remove PageReserved From: Nigel Cunningham Reply-To: ncunningham@cyclades.com In-Reply-To: <42F83D04.7090802@yahoo.com.au> References: <42F57FCA.9040805@yahoo.com.au> <200508090710.00637.phillips@arcor.de> <1123562392.4370.112.camel@localhost> <42F83849.9090107@yahoo.com.au> <1123564294.4370.119.camel@localhost> <42F83D04.7090802@yahoo.com.au> Content-Type: text/plain Message-Id: <1123565413.4370.127.camel@localhost> Mime-Version: 1.0 Date: Tue, 09 Aug 2005 15:30:13 +1000 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Daniel Phillips , Linux Kernel Mailing List , Linux Memory Management , Hugh Dickins , Linus Torvalds , Andrew Morton , Andrea Arcangeli , Benjamin Herrenschmidt List-ID: Hi. On Tue, 2005-08-09 at 15:20, Nick Piggin wrote: > Nigel Cunningham wrote: > > Hi Nick et al. > > > > On Tue, 2005-08-09 at 14:59, Nick Piggin wrote: > > >>>Changing the e820 code so it sets PageNosave instead of PageReserved, > >>>along with a couple of modifications in swsusp itself should get rid of > >>>the swsusp dependency. > >>> > >> > >>That would work for swsusp, but there are other users that want to > >>know if a struct page is valid ram (eg. ioremap), so in that case > >>swsusp would not be able to mess with the flag. > > > > > > Um. Mess with which flag? I guess you mean Reserved. I was saying that > > Mess with PageNosave (if that is what we used to denote a struct page > not pointing to valid RAM). > > Ie. when swsusp allocates its save map (or whatever it calls it), setting > PageNosave would make other parts of the kernel think the area is not > valid ram. Ok. I guess I should have looked, but I thought the suspend implementations were the only users of Nosave. > In other words - we can't combine swsusp's PageNosave with our mythical > PageValidRAM. > > > imaging Reserved going away, so for the short term I'd be meaning making > > the e820 set both Nosave and Reserved for those pages (which is what the > > Suspend2 patches do so as to play nicely with swsusp - I don't use > > Reserved at all). > > > > In the short term, PageReserved can stay around - swsusp does still > work if I hadn't made that clear. Yeah. > By the way - how does swsusp2 handle this problem if not using > PageReserved? At the places where Reserved is currently set and cleared, I set and clear Nosave as well. Then I only use Nosave. Swsusp still works fine (although I have to comment out a bogus bug_on()) and suspend2 can clear and set additional pages' Nosave flags while it runs (equivalents to Pavel's nosave_free pages and also pages allocated for checksumming when I get paranoid). Regards, Nigel -- Evolution. Enumerate the requirements. Consider the interdependencies. Calculate the probabilities. -- 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: email@kvack.org