From mboxrd@z Thu Jan 1 00:00:00 1970 From: Minchan Kim Subject: Re: [PATCH v3 01/17] mm: support madvise(MADV_FREE) Date: Fri, 13 Nov 2015 16:03:56 +0900 Message-ID: <20151113070356.GG5235@bbox> References: <1447302793-5376-1-git-send-email-minchan@kernel.org> <1447302793-5376-2-git-send-email-minchan@kernel.org> <564421DA.9060809@gmail.com> <20151113061511.GB5235@bbox> <56458056.8020105@gmail.com> <20151113063802.GF5235@bbox> <56458720.4010400@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Return-path: In-Reply-To: <56458720.4010400@gmail.com> Content-Disposition: inline Sender: owner-linux-mm@kvack.org To: Daniel Micay Cc: Andy Lutomirski , Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , Michael Kerrisk , Linux API , Hugh Dickins , Johannes Weiner , Rik van Riel , Mel Gorman , KOSAKI Motohiro , Jason Evans , "Kirill A. Shutemov" , Shaohua Li , Michal Hocko , yalin wang List-Id: linux-api@vger.kernel.org On Fri, Nov 13, 2015 at 01:45:52AM -0500, Daniel Micay wrote: > > And now I am thinking if we use access bit, we could implment MADV_FREE_UNDO > > easily when we need it. Maybe, that's what you want. Right? > > Yes, but why the access bit instead of the dirty bit for that? It could > always be made more strict (i.e. access bit) in the future, while going > the other way won't be possible. So I think the dirty bit is really the > more conservative choice since if it turns out to be a mistake it can be > fixed without a backwards incompatible change. Absolutely true. That's why I insist on dirty bit until now although I didn't tell the reason. But I thought you wanted to change for using access bit for the future, too. It seems MADV_FREE start to bloat over and over again before knowing real problems and usecases. It's almost same situation with volatile ranges so I really want to stop at proper point which maintainer should decide, I hope. Without it, we will make the feature a lot heavy by just brain storming and then causes lots of churn in MM code without real bebenfit It would be very painful for us. -- 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