Welcome to the home page of Linux-MM

This site is supposed to provide documentation on the Linux memory management subsystem and to give a good overview of what's happening in the Linux MM community. If you have requests, ideas or contributions to make, please let us know.

If you want to learn about the kernel, or have a "basic" question about memory management, please use the kernelnewbies website, mailing-list or IRC channel.

Have fun,

ChangeLog / News

• Jun 13, after many months of inactivity I've finally gotten around to migrating the site to the new host. The content is outdated in many places and I'll have to update links, etc...
• Jun 13, link to the MM Bugs in the kernel.org bugzilla. Now to find a way to automagically display those bugs on a page here ;)

• Dec 22nd, Rik van Riel is making regular snapshots of his VM work available as patches and as the full bitkeeper tree.
• Dec 13th, added Andrea Arcangeli's talk on the new 2.4 VM implementation to the documentation section.
• Aug 15th, in order to make it easier to put our points of view online and keep them there, a Wiki wiki clone has been added to this site.
• Mar 17th, Nico Schmoigl has ported the badram and memmap patches to the 2.4 kernel. This should make it possible to run 2.4 reliably on machines with single-bit errors in RAM, see his badram/memmap home page for more information.
• Feb 1st, Rik van Riel wrote a small document describing the Out of Memory killer.
• Feb 1st, the linux-mm.org domain is now up and running. Oh, and we're still looking for people willing to help us keep the information on this page up-to date ;)
• Jan 31st, the Linux kernel MM subsystem now has a Bugzilla (thanks to Conectiva).
• Jan 8th, Rik van Riel released 2.4.0-vmbigpatch, it includes improved RSS ulimit enforcement, documentation updates, a smarter page_launder(), and more. Visit Rik's patches page for an up-to-date description.
• Jan 5th, the TODO list has finally been updated. Apologies by Rik for delaying this so long.

• Dec 28th, Rik van Riel released a patch that enforces RSS limits in the 2.4 kernel.
• Dec 22nd, Ingo Oeser released a patch that adds an OOM handler API to the 2.4 kernel.
• Dec 19th, Christoph Hellwig announces the kiobuf-io-devel mailinglist devoted to the development of kiobuf based IO patches.
• May 26th, after a few days of work by Juan Quintela and Rik van Riel a "sneak preview" patch of the beginnings of the new VM subsystem are available. The patch works and implements deferred swap and page aging for the pages on the active list.
• May 24th, Matt Dillon of FreeBSD fame has entered a discussion about the merits of different VM organisations. After a few days this has lead to a new design for Linux VM, to be coded up right now and included before Linux kernel version 2.4. Comments are very much welcome!
• Jan 22nd, an IRC channel has been setup on the Open Projects Network. #kernelnewbies on irc.openprojects.net is there for people who would like to learn about the kernel.
• Jan 10th, we somehow missed to mention this news, but Pauline Middelink has now taken charge of the Bigphysarea patch (needed to allocate larger amounts of physically contiguous memory), see her hobby page for details.

• Nov 16th, this is getting confusing; Ingo has been making patch after patch after patch of the zoned allocator. So far I've seen 2.3.80-G4, G5, H2, J5 and K2. If you understand the logic behind this versioning scheme, please mail us :)
• Nov 14th, since kernel version 2.3.28 the kernel supports large files (> 2GB) on x86 machines. Matti Aarnio's LFS patches have been integrated and the maximum file size on ext2 with 4k block sizes is now 8TB.
• Oct 31st, Linux now (kernel >2.3.24) supports up to 64GB of physical memory and up to several terabytes (that's no typo) of swap space. This, of course, means that the Linux and >1GB of RAM HOWTO is now obsolete.
• Jul 19th, the site is placed under CVS and I'm looking for volunteers who want to help me keep the site up to date.
• May 16th, DICP 1.1c is out. DIPC (Distributed Inter-Process Communication) allows you to use IPC mechanisms over a network in order to build clusters (multi-computers).
• May 15th, there are problems with the fs/buffer.c in 2.2.8. Please use kernel version 2.2.7 or 2.2.9.
• May 8th, Eric Biederman has published a set of patches to allow dirty pages in the page cache, large file (>2GB) support and several other things. Go grab it and tell the Linux-MM list what you think of it.
• Mar 30th, with kernel 2.2.5, Linux seems to have reached enterprise stability. At least it's so stable that Linus is confident enough to take a 2 week vacation. I guess this is the time to massively upgrade your servers to 2.2 :)
• Feb 24th, kernel 2.2.2 is out. It seems to have solved all remaining problems (rebooting, skipping mp3s, etc) for me. I'll start producing kernel patches again next week.
• Feb 19th, during a linux-kernel discussion, I glimpsed a beautiful performance measuring addition to the kernel: Stephen Tweedie's SAR replacement for Linux. If you want to do serious performance measurements, you will need this piece of art.
• Feb 9th, I've been busy with a number of new Linux mailing lists. There's one about the future of the Linux kernel, one about kernel documentation and one about the legal issues involved with Linux. The MM layer seems to have stabilized in time for 2.2. This means there's not much news to offer so I'll spend more time on the rest of this server.
• Feb 1st, Manfred Spraul sent this patch to the Linux-Kernel mailing list. It is supposed to give Linux the ability to use memory > 960MB/2GB as a ramdisk, swap area or whatever. It should be useful to the database and simulation folks, at least.
• Jan 25th, I am very busy, but have caught this link from LWN. It contains a good analysis of the Linux VM system by one of the *BSD gurus. I've also added this one to the TODO page.
• Jan 22nd, apparently 2.2.0-final will really be the final one. Nobody has found anything really embarrassing so I guess you should prepare for 2.2.0. If you are truly paranoid and haven't tested the 2.2 kernel yet, you should now or remain silent until the end of days. Consider this your last warning!
• Jan 21st, Linus put out 2.2.0-pre^H^H^Hfinal. I don't know whether that's a good thing or not, but he seems to be fairly confident that there's nothing left that's so embarrassing that he'll have to wear a brown paper bag over his head the next month. Guess this means you'll all have to download the thing now and test it. Compulsory!
• Jan 14th, hot link of the day: Kernel Traffic.
• Jan 13th, Linus just released kernel version 2.2.0-pre7. This version contains a fix for the possible deadlock situations in earlier versions so I recommend that you grab a copy of the new tree. This version should also fix the performance problems of -pre6.
• Jan 8th, there is a bug in kernel 2.2.0-pre5 that can be triggered in extreme circumstances. Linus has put out a fix (which is available somewhere in our mailing list archive).
• Jan 6th, I have made the first version of the European Universities' Linux User Groups pages. This is a project to bring the different European hacker/students and university LUGs together. Check it out if you are a student or close to a university LUG. We also have a few mailing lists that could be of interest to you.
• Jan 4th, Andrea and Linus are working on a better-than-ever-before VM system. That could be fun (and a good reason to upgrade to 2.2 if you have a small machine).

How to support this site:

• Write Linux MM stuff and tell us about it.
• Contribute documentation on how stuff works, or on how to tune the MM to work well with unusual workloads.