On Tue, Oct 06, 2020 at 11:10:41AM -0700, David Rientjes wrote: > Thanks Peter. > > The series of commits certainly expanded from my initial set that I asked > about in a thread with the subject "DMA API stable backports for AMD SEV" > on May 19. Turns out that switching how DMA memory is allocated based on > various characteristics of the allocation and device is trickier than > originally thought :) There were a number of fixes that were needed for > subtleties and cornercases that folks ran into, but were addressed and > have been merged by Linus. I believe it's stable in upstream and that > we've been thorough in compiling a full set of changes that are required > for 5.4. > > Note that without this series, all SEV-enabled guests will run into the > "sleeping function called from invalid context" issue in the vmalloc layer > that Peter cites when using certain drivers. For such configurations, > there is no way to avoid the "BUG" messages in the guest kernel when using > AMD SEV unless this series is merged into an LTS kernel that the distros > will then pick up. > > For my 13 patches in the 30 patch series, I fully stand by Peter's > backports and rationale for merge into 5.4 LTS. Given that this "feature" has never worked in the 5.4 or older kernels, why should this be backported there? This isn't a bugfix from what I can tell, is it? And if so, what kernel version did work properly? And if someone really wants this new feature, why can't they just use a newer kernel release? thanks, greg k-h
