On 08/09/2018 07:53 PM, Theodore Y. Ts'o wrote: > On Tue, Jul 31, 2018 at 01:27:15PM -0700, Dave Jiang wrote: >> >> On 7/31/2018 12:36 PM, Ross Zwisler wrote: >>> On Mon, Jul 30, 2018 at 07:53:12PM -0400, Theodore Y. Ts'o wrote: >>>> In newer kernels, it looks like you can't use /dev/pmem0 for DAX >>>> unless it's marked as being DAX capable. This appears to require >>>> CONFIG_NVDIMM_PFN. But when I tried to build a kernel with that >>>> configured, I get the following BUG: >>> >>> You're using the memmap kernel command line parameter to reserve normal >>> memory to be treated as normal memory, but you've also got kernel address >>> randomization turned on in your kernel config: >>> >>> CONFIG_RANDOMIZE_BASE=y >>> CONFIG_RANDOMIZE_MEMORY=y >>> >>> You need to turn these off for the memmap kernel command line parameter, else >>> the memory we're using could overlap with addresses used for other things. >> >> I believe this issue was fixed a while back. Although we probably can see if >> that is the issue or something else. > > I turned off RANDOMIZE_BASE and RANDOMIZE_MEMORY, but that didn't fix > my problem. > > It turns out the problem was KASAN. It looks like using memmap to > create test /dev/pmemX devices is not compatible with CONFIG_KASAN > being enabled. > > So I have a workaround for now, but it seems this to be a bug in > KASAN, or at least an unfortunate interaction between KASAN and > NVDIMM_PFN. Thanks Ted. I have updated the wiki Ross mentioned to reflect that.
