On Sat, Mar 28, 2020 at 02:50:43AM +0900, Tokunori Ikegami wrote: > On 2020/03/25 1:51, Tokunori Ikegami wrote: > > On 2020/03/24 9:02, Keith Busch wrote: > > > We didn't have 32-bit max segments before, though. Why was 16-bits > > > enough in older kernels? Which kernel did this stop working? > > Now I am asking the detail information to the reporter so let me > > update later. That was able to use the same command script with the > > large data length in the past. > > I have just confirmed the detail so let me update below. > > The data length 20,531,712 (0x1394A00) is used on kernel 3.10.0 (CentOS > 64bit). > Also it is failed on kernel 10 4.10.0 (Ubuntu 32bit). > But just confirmed it as succeeded on both 4.15.0 (Ubuntu 32bit) and 4.15.1 > (Ubuntu 64bit). > So the original 20,531,712 length failure issue seems already resolved. > > I tested the data length 0x10000000 (268,435,456) and it is failed > But now confirmed it as failed on all the above kernel versions. > Also the patch fixes only this 0x10000000 length failure issue. This is actually even more confusing. We do not support 256MB transfers within a single command in the pci nvme driver anymore. The max is 4MB, so I don't see how increasing the max segments will help: you should be hitting the 'max_sectors' limit if you don't hit the segment limit first.
