On Fri, 2015-05-29 at 12:34 -0700, Dan Williams wrote: > On Fri, May 29, 2015 at 11:32 AM, Toshi Kani <toshi.kani@xxxxxx> wrote: > > On Fri, 2015-05-29 at 11:19 -0700, Dan Williams wrote: > >> On Fri, May 29, 2015 at 8:03 AM, Toshi Kani <toshi.kani@xxxxxx> wrote: > >> > On Fri, 2015-05-29 at 07:43 -0700, Dan Williams wrote: > >> >> On Fri, May 29, 2015 at 2:11 AM, Borislav Petkov <bp@xxxxxxxxx> wrote: > >> >> > On Wed, May 27, 2015 at 09:19:04AM -0600, Toshi Kani wrote: > >> >> >> The pmem driver maps NVDIMM with ioremap_nocache() as we cannot > > : > >> >> >> - pmem->virt_addr = ioremap_nocache(pmem->phys_addr, pmem->size); > >> >> >> + pmem->virt_addr = ioremap_wt(pmem->phys_addr, pmem->size); > >> >> >> if (!pmem->virt_addr) > >> >> >> goto out_release_region; > >> >> > > >> >> > Dan, Ross, what about this one? > >> >> > > >> >> > ACK to pick it up as a temporary solution? > >> >> > >> >> I see that is_new_memtype_allowed() is updated to disallow some > >> >> combinations, but the manual seems to imply any mixing of memory types > >> >> is unsupported. Which worries me even in the current code where we > >> >> have uncached mappings in the driver, and potentially cached DAX > >> >> mappings handed out to userspace. > >> > > >> > is_new_memtype_allowed() is not to allow some combinations of mixing of > >> > memory types. When it is allowed, the requested type of ioremap_xxx() > >> > is changed to match with the existing map type, so that mixing of memory > >> > types does not happen. > >> > >> Yes, but now if the caller was expecting one memory type and gets > >> another one that is something I think the driver would want to know. > >> At a minimum I don't think we want to get emails about pmem driver > >> performance problems when someone's platform is silently degrading WB > >> to UC for example. > > > > The pmem driver creates an ioremap map to an NVDIMM range first. So, > > there will be no conflict at this point, unless there is a conflicting > > driver claiming the same NVDIMM range. > > Hmm, I thought it would be WB due to this comment in is_new_memtype_allowed() > > /* > * PAT type is always WB for untracked ranges, so no need to check. > */ This comment applies to the ISA range, where ioremap() does not create any mapping to, i.e. untracked. You can ignore this comment for NVDIMM. Thanks, -Toshi -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>