Linux 4.19-rc1 Released Following "A Fairly Frustrating Merge Window"

As expected, Linus Torvalds has closed the merge window for 4.19 and released Linux 4.19-rc1.

Of the past two weeks for the Linux 4.19 merge window, Linus commented:

So two weeks have passed, and the merge window for 4.19 is over.

This was a fairly frustrating merge window, partly because 4.19 looks to be a pretty big release (no single reason), and partly just due to random noise. We had the L1TF hw vulnerability disclosure early in the merge window, which just added the usual frustration due to having patches that weren't public. That just shows just how good all our infrastructure for linux-next and various automated testing systems have become, in how painful it is when it's lacking.

At least we didn't actually have a lot of problems on that front in the mainline kernel, there seemed to be many more pain points in the backports.

We also had a report of a TLB shootdown bug come in during this merge window, and while the patches for ended up not being a huge problem, TLB invalidation issues is actually one of the things that stresses me out. They're really nasty to debug (thanks to Jann Horn for pinpointing this one), and our interfaces to the architecture specific routines are subtle and pretty complicated. And messy. I think the discussion will result in a few cleanups later, but timing could have been so much better for this.

Oh well. I guess I can partly just blame myself for having delayed 4.18 by a week, which just made everything happen during that first and busiest week of the merge window. Bad luck. Although even the second week - when things usually calm down - was also pretty busy this time around.

Anyway, on to the actual changes. And there' a lot of them. There's just a lot of things going on, and while this isn't the biggest release we've had (4.9 still keeps that crown), this does join 4.12 and 4.15 as one of the bigger kernel releases, at least just judging by number of commits in the merge window.

As usual, there's way too many patches to list even in shortlog format, but appended is my usual "mergelog" of people I merged from and a one-liner overview of the merge. There's actually a couple of pull requests that I might still look at after the merge window, but that are probably in the "there's always the next one" pile.

The "big picture" of the merge window looks pretty normal: just under two thirds of the changes are to drivers (gpu and network drivers being the bulk - as usual), with the rest being architecture updates (all the usual suspects), filesystems, core kernel and networking. There's a fair chunk of documentation and tooling updates too (selftests, tracing, perf..).

Anyway, go forth and test,

Linus

See our Linux 4.19 feature overview to learn about all of the big changes in this next kernel release.