From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Torvalds Subject: Re: [RFC] Heterogeneous memory management (mirror process address space on a device mmu). Date: Tue, 6 May 2014 07:57:02 -0700 Message-ID: References: <1399038730-25641-1-git-send-email-j.glisse@gmail.com> <20140506102925.GD11096@twins.programming.kicks-ass.net> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: j.glisse@gmail.com, linux-mm , Linux Kernel Mailing List , linux-fsdevel , Mel Gorman , "H. Peter Anvin" , Andrew Morton , Linda Wang , Kevin E Martin , Jerome Glisse , Andrea Arcangeli , Johannes Weiner , Larry Woodman , Rik van Riel , Dave Airlie , Jeff Law , Brendan Conoboy , Joe Donohue , Duncan Poole , Sherry Cheung , Subhash Gutti , John Hubbard , Mark Hairgrove , Lucien Dunning , Cameron Buschar To: Peter Zijlstra Return-path: In-Reply-To: <20140506102925.GD11096@twins.programming.kicks-ass.net> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Tue, May 6, 2014 at 3:29 AM, Peter Zijlstra wrote: > > So you forgot to CC Linus, Linus has expressed some dislike for > preemptible mmu_notifiers in the recent past: Indeed. I think we *really* should change that anonvma rwsem into an rwlock. We had performance numbers that showed it needs to be done. The *last* thing we want is to have random callbacks that can block in this critical region. So now I think making it an rwlock is a good idea just to make sure that never happens. Seriously, the mmu_notifiers were misdesigned to begin with, and much too deep. We're not screwing up the VM any more because of them. Linus -- 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