Re: [PATCH stable v5.10 0/7] arm64: Default to 32-bit wide ZONE_DMA

[Greg KH]

On Mon, Mar 08, 2021 at 11:20:03AM +0800, Jing Xiangfeng wrote:
> 
> 
> On 2021/3/7 23:24, Greg KH wrote:
> > On Thu, Mar 04, 2021 at 04:09:28PM +0100, Nicolas Saenz Julienne wrote:
> > > On Thu, 2021-03-04 at 15:17 +0100, Greg KH wrote:
> > > > On Thu, Mar 04, 2021 at 03:05:32PM +0100, Nicolas Saenz Julienne wrote:
> > > > > Hi Greg.
> > > > > 
> > > > > On Thu, 2021-03-04 at 14:46 +0100, Greg KH wrote:
> > > > > > On Wed, Mar 03, 2021 at 03:33:12PM +0800, Jing Xiangfeng wrote:
> > > > > > > Using two distinct DMA zones turned out to be problematic. Here's an
> > > > > > > attempt go back to a saner default.
> > > > > > What problem does this solve?  How does this fit into the stable kernel
> > > > > > rules?
> > > > > We changed the way we setup memory zones in arm64 in order to cater for
> > > > > Raspberry Pi 4's weird DMA constraints: ZONE_DMA spans the lower 1GB of memory
> > > > > and ZONE_DMA32 the rest of the 32bit address space. Since you can't allocate
> > > > > memory that crosses zone boundaries, this broke crashkernel allocations on big
> > > > > machines. This series fixes all this by parsing the HW description and checking
> > > > > for DMA constrained buses. When not found, the unnecessary zone creation is
> > > > > skipped.
> > > > What kernel/commit caused this "breakage"?
> > > 1a8e1cef7603 arm64: use both ZONE_DMA and ZONE_DMA32
> > Thanks for the info, all now queued up.
> There is a fix in 5.11. Please consider applying the following commit to
> 5.10.y:
> 
> aed5041ef9a3 of: unittest: Fix build on architectures without
> CONFIG_OF_ADDRES

Thanks, now queued up.

greg k-h