From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by nz-out-0506.google.com with SMTP id s1so544076nze for ; Mon, 22 Oct 2007 10:03:20 -0700 (PDT) Message-ID: <45a44e480710221003u4b6d9e84n98599c97b9dab95@mail.gmail.com> Date: Mon, 22 Oct 2007 13:03:20 -0400 From: "Jaya Kumar" Subject: Re: vm_ops.page_mkwrite() fails with vmalloc on 2.6.23 In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <1193064305.16541.3.camel@matrix> Sender: owner-linux-mm@kvack.org Return-Path: To: Hugh Dickins Cc: Stefani Seibold , Peter Zijlstra , linux-mm@kvack.org List-ID: On 10/22/07, Hugh Dickins wrote: > > Interesting. You need to ask Jaya (CC'ed) since he's the one > who put that code into fb_defio.c, exported page_mkclean, and > should have tested it. Thanks Hugh. Yes, hecubafb uses fb_defio (which is infrastructure code) which uses mkwrite/mkclean. This was tested and it worked great on x86 with 2.6.21 when I posted the patches. I will be trying in the next few weeks to finish up a driver for the current E-Ink Vizplex+controller working on arm with 2.6.22. So since page_mkclean has changed, I will try to work on a update for fb_defio at that time. > > > > > I am not sure if the is a feature of the new rmap code or a bug. > > page_mkclean was written in the belief that it was being used on > pagecache pages. I'm not sure how deeply engrained that belief is. > > If it can easily and safely be used on something else, that may be > nice: though there's a danger we'll keep breaking and re-breaking > it if there's only one driver using it in an unusual way. CC'ed > Peter since he's the one who most needs to be aware of this. Yes, right now, only hecubafb uses deferred IO and thus page_mkclean. But I believe that usage will increase. I hope together we can get it fixed up and keep it working long term. I think deferred IO gives linux a nice advantage when interfacing with high latency displays (of which one will increasingly see more of). Thanks, jaya -- 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