On Thu, Oct 09, 2025 at 01:50:11PM +0800, Vivian Wang wrote:
On 10/9/25 13:00, Greg KH wrote:
On Thu, Oct 09, 2025 at 12:19:46PM +0800, Vivian Wang wrote:
[...]
Ok, that makes a bit more sense, but again, why is this just showing up now? What changed to cause this to be noticed at and needed to be fixed at this moment in time and not before?
As of why this came quite late in the lifetime of the 6.6.y branch, I believe it's a combination of two factors.
Firstly, actual Sv48-capable RISC-V hardware came fairly late. Milk-V Megrez (with Eswin EIC7700X), on which the Go TSAN thing ran, was shipped only early this year. The DC ROMA II laptop (EIC7702X) and Framework mainboard with the same SoC has not even shipped yet, or maybe only shipped to developers - I'm not so certain. Most other RISC-V machines only have Sv39.
Secondly, there is interest among some Chinese software vendors to ship Linux distros based on a 6.6.y LTS kernel. The "RISC-V Common Kernel" (RVCK) project [1], with support from openEuler and various HW vendors, maintains backports on top of a 6.6.y kernel. "RockOS" [2] is a distro maintained by PLCT Lab, ISCAS, for EIC770{0,2}X-based boards, and it has a 6.6.y kernel branch. Both have cherry-picked the mmap patches for now.
We operate with the understanding that the official stable kernel will not be accepting new major features and drivers, but fixes do belong in stable, and at least from the perspective of PLCT Lab we generally try to send patches instead of hoarding them. Hence, the earlier backport request and this backport series.
I hope this explanation is acceptable.
Thanks for the detailed explaination. I've queued these up now.
But wow, shipping new products on a 2 year old kernel feels very risky to me, but hey, what do I know? :)
PS: This 6.6 kernel thing isn't just a RISC-V thing, by the way. KylinOS V11 has shipped in August with a 6.6 kernel. Deepin and UOS will be shipping with 6.6, with UOS "25" shipping maybe late this year or early 2026.
That too is crazy. They should know better.
Just to give a bit of context for this, for the latest 6.6.y release, 6.6.110, there are currently over 300 documented unfixed CVE items in that branch. Feels rough to be doing a new release based on that...
good luck!
greg k-h