Following up to feedback on his merge plans [story], Andrew Morton [interview] posted an updated summary of what he is pushing upstream for inclusion in the upcoming 2.6.22 kernel. His list included, "a few serial bits, a few pcmcia bits, one little security patch, the blackfin architecture, small h8300 update, small alpha update, swsusp updates, m68k bits, and lots of UML updates." He also noted that he'll push some of the memory management queue including, "an enhancement to /proc/pid/smaps to permit monitoring of a running program's working set. The SLUB allocator, it's pretty green but I do want to push ahead with this pretty aggressively with a view to replacing slab altogether. Generic pagetable quicklist management. We have x86_64 and ia64 and sparc64 implementations, but I'll only include David's sparc64 implementation here. I'll send the x86_64 and ia64 implementations through maintainers."
Following the release of the 2.6.21 kernel [story] Andrew Morton [interview] posted a list of patches in his -mm kernel, summarizing for each his plans as to whether or not they wil be pushed upstream for inclusion in the upcoming 2.6.22 kernel. He noted, "the overall stability in recent -mm's was not sufficiently high and we ran out of time to find all the bugs. I shouldn't have merged all those patches last week - they contained an exceptional amount of garbage. This all means that more bugs than usual will probably leak into mainline, and we'll have to fix them there." He went on to add, "I've been ducking most non-bugfix patches recently. I have ~200 feature and cleanup patches queued for later consideration, so people who sent those will be hearing from me eventually."
Following the release of the 2.6.20 kernel [story] Andrew Morton [interview] posted a list of patches in his -mm kernel, summarizing for each his plans as to whether or not they will be pushed upstream for inclusion in the upcoming 2.6.21 kernel. Andrew commented, "I'm getting fed up of holding onto hundreds of patches against subsystem trees, sending them over and over again and seeing nothing happen. I sent 242 patches out to subsystem maintainers on Monday and look at what's still here." In response to some confusion as to what happens to these patches, he went on explain, "once a subsystem has a subsystem tree (git or quilt) I basically never merge anything which belongs to that tree. It's always originator->mm->subsystemtree->Linus".
Andrew Morton [interview] posted his patch queue with numerous comments about merge plans into the mainline kernel. Among his comments he noted that he would not yet be merging the Reiser4 filesystem [story], "reiser4. I was planning on merging this, but the batch_write/writev problemight wreck things, and I don't think the patches arising from my recent partial review have come through yet. So it's looking more like 2.6.20."
A large discussion followed Andrew's posting that focused on the current kernel development process [story]. Andrew expressed his concerns on what's currently happening, "people seem to treat the stabilisation period as a wonderful quiet time in which to run off and develop new features, rather than participating in the stabilisation. This has the following effects: 1: release cycles get longer 2: the kernel has more bugs 3: we put new features into the kernel faster than we otherwise would (see 2:, above)." Alan Cox [interview] proposed an idea, "a suggestion from the department of evil ideas: Call even cycles development odd ones stabilizing. Nothing gets into an odd one without a review and linux-kernel signoff/ack?" Linus Torvalds replied favorably, going on to note that he was surprised at how well the decision to only accept big merges in the two weeks following a major release has been accepted, "I actually expected people to dislike arbitrary rules more than they do, but I've come to believe that people _like_ having rules that they have to obey, as long as it's not a big pain for them. In other words, arbitrary rules are not actually disliked at all, people actually _like_ them, because suddenly there's less need for making unnecessary judgement decisions." Linus went on to spell out the idea further, "2.6.<odd> is 'the big initial merges with all the obvious fixes to make it all work' (ie roughly the current -rc2 or perhaps -rc3). 2.6.<even> is 'no big merges, just careful fixes' (ie the current 'real release')". He went on to caution:
"That said, I think Andrew was of the opinion that it doesn't really _fix_ anything, and he may well be right. What's the point of the odd release, if the weekly snapshots after that are supposed to be strictly better than it anyway? So I think I may like it just because it _seems_ to combine the good features of both the old naming scheme and the current one, but I suspect Andrew may be right in that it doesn't _really_ change anything, deep down."
Andrew Morton [interview] posted an overview of patches in -mm, discussing what is destined for inclusion in the upcoming 2.6.18 Linux kernel. He noted, "there is an unusually large amount of difficult material here." Patch sets that were discussed include a cleanup of kernel headers, klibc, various subsystem cleanups, the ACX1xx wireless driver, swsup cleanups, per-task statistic metrics, a clocksource management infrastructure, smpnice, swap prefetching [story], priority-inheriting futexes, a revamp of /proc/pid, ecryptfs, utsname virtualization [story], readahead, reiser4 improvements, a statistics infrastructure, and lock validation code.
Following up on a couple of features discussed earlier on KernelTrap, both swap-prefetching and utsname virtualization were briefly discussed. In regards to swap-prefetching Andrew noted, "I remain skeptical, but I have a lot of RAM. Multiple people have sung its praises. I guess I'll re-review and tentatively plan on sending them along or 2.6.18. Opinions are sought." As for utsname virtualization, "this doesn't seem very pointful as a standalone thing. That's a general problem with infrastructural work for a very large new feature. So probably I'll continue to babysit these patches, unless someone can identify a decent reason why mainline needs this work. I don't want to carry an ever-growing stream of OS-virtualisation groundwork patches for ever and ever so if we're going to do this thing... faster, please."
Andrew Morton [interview] offered a list of patches in his mm tree, summarizing for each his plans as to whether or not they will be pushed to Linus for inclusion in the upcoming 2.6.17 kernel. Comments on the patches range from the simple "will merge" to pushing them to others for review. One of the more entertaining comments followed a set of 33 patches where Andrew noted, "This is Oleg's romp through the core kernel. There's a ton of material here. I'll probably send it all to Linus and ask him to review it. (aka blame-shifting)." Later in the thread he explained, "it's just a whole lot of code in areas which are tricky and in which few people work and in which reviewing resources are slight."
One set of patches refused with the comment, "still don't have a compelling argument for this, IMO" was Con Kolivas [interview]' swap prefetching efforts [story]. The feature was discussed in a couple of follow up threads. In response to some concerns raised by Jens Axboe, Con explained the implementation a little further, "If the system is idle it doesn't cost anything to bring those pages in (laptop mode disables any prefetching if you're thinking about power consumption on laptops). And if the system wants the ram that has been filled with prefetched pages wrongly, the prefetched pages are at the tail end of the inactive LRU list with a copy on backing store so if they're not accessed they'll be the first thing dropped in preference to anything else, without any I/O."
Andrew Morton [interview] provided an update on the current development status of the Linux kernel. As of his announcement, the latest development release is 2.6.13-git5, with 2.6.14 expected around October 7'th. At this time, Andrew is tracking 144 bugs though he notes, "I haven't culled these yet - some may be fixed." Indeed, a number of replies indicated that several of the listed bugs have been fixed.
As for what will likely be merged in the next couple of weeks and be part of the upcoming 2.6.14 release, Andrew listed several filesystems including relayfs [story], v9fs [story], and FUSE [story]. Regarding the latter he noted that he was, "fed up with arguing - any remaining problems can be fixed up in-tree if anyone can think of how to fix them." As for much anticipated Reiser4, Andrew summarized, "Stuck. Last time we discussed this I asked the reiser4 team to develop and negotiate a bullet-point list of things to be addressed. Once that's agreed to, implement it and then we can merge it. None of that has happened and as far as I know, all the review feedback which was provided was lost."
In response to whether or not he had any objections to merging FUSE [story] into the mainline kernel, Andrew Morton [interview] offered some insight into what new features were slated for the upcoming 2.6.12 kernel. Andrew began, "I was planning on sending FUSE onto Linus in a week or two," going on to add "that and cpusets are the notable features which are 2.6.12 candidates."
Andrew then referred to several other patches currently in his -mm patchset [story], discussing their likelihood of being merged into the mainline kernel. He described crashdump [story] as seeming "permanently not-quite-ready". He noted that perfctr "works fine", but that it was "similar-to-but-different-from" the IA64 perfmon subsystem, and "might not be suitable for ppc64". Both nfsacl [thread] and the device-mapper multipath [thread] patches were deemed "OK for 2.6.12". Regarding cachefs, Andrew noted it "is a bit stuck because it's a ton of complex code and afs is the only user of it. Wiring it up to NFS would help." Finally, regarding whether or not he planned to merge reiser4 [story], he said this was "less clear" going on to add "once all the review comments have been addressed and we start seeing a bit of vendor pull for it, maybe."
With the release of 2.6.9-mm1, Andrew Morton [interview] offered a quick status update on a number of patches in his -mm tree [forum] that are 2.6-mainline hopefuls. For example, regarding the much debated reiser4 filesystem [story], Andrew said that he is still "not sure, really. The namespace extensions were disabled, although all the code for that is still present. Linus's filesystem criterion used to be 'once lots of people are using it, preferably when vendors are shipping it'. That's a bit of a chicken and egg thing though. Needs more discussion". And as for Ingo Molnar [interview]'s preemption and low-latency fixups [forum] Andrew offered, "I haven't really thought about it and haven't looked at the patches yet. Hopefully 2.6.10 material."
Other projects specifically mentioned include the sysfs backing store, the ext3 reservations code, the ext3 resize code, kexec and crashdump [story], perfctr, cachefs, cpusets, and the md updates. Read on for Andrew's comments and the complete -mm1 changelog.