Linus lately has been pretty committed to putting out new kernel versions on Sundays, but this time he did a Friday night release due to travel conflicts and RC5 being too large for this stage of the kernel cycle.
While Linux 3.15-rc5 is coming in heavy, Linus Torvalds isn't too mad about the situation:
I'd have been happier if it had been as small as rc4 was, it seems to all be solid fixes (famous last words). The interesting dcache list corruption I mentioned as being pending for rc4 is in, and it would be lovely if you have any VFS layer stress-testing that interacts with memory pressure, but the race was tiny to begin with, and the fix actually cleaned things up a lot and removed more lines than it added, so I feel good about it.
Apart from that one interesting really core change (where "really core" is defined as "an area I personally care about and muck around with", and not meant to be a value statement in any other way ;), it all looks boringly familiar: 55% drivers, 20% architecture updates, and 25% misc (filesystems, core networking, VM, etc).
And while rc5 may be bigger than rc3/4 were, it's not like it is worrying. This merge window was bigger than most, and the fact that rc5 is then slightly bigger than most isn't something that worries me overmuch. And since rc4 was smaller than usual, it all evens out.
Those wishing to find out more about the Linux 3.15-rc5 release can see the kernel release announcement. Overall, there's many new features to the Linux 3.15 kernel.