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. - Ted
