Dan Williams dan.j.williams@intel.com writes:
On Wed, Apr 17, 2019 at 3:59 PM Dan Williams dan.j.williams@intel.com wrote:
On Wed, Apr 17, 2019 at 3:04 PM Andrew Morton akpm@linux-foundation.org wrote:
On Wed, 17 Apr 2019 11:38:55 -0700 Dan Williams dan.j.williams@intel.com wrote:
The memory hotplug section is an arbitrary / convenient unit for memory hotplug. 'Section-size' units have bled into the user interface ('memblock' sysfs) and can not be changed without breaking existing userspace. The section-size constraint, while mostly benign for typical memory hotplug, has and continues to wreak havoc with 'device-memory' use cases, persistent memory (pmem) in particular. Recall that pmem uses devm_memremap_pages(), and subsequently arch_add_memory(), to allocate a 'struct page' memmap for pmem. However, it does not use the 'bottom half' of memory hotplug, i.e. never marks pmem pages online and never exposes the userspace memblock interface for pmem. This leaves an opening to redress the section-size constraint.
v6 and we're not showing any review activity. Who would be suitable people to help out here?
There was quite a bit of review of the cover letter from Michal and David, but you're right the details not so much as of yet. I'd like to call out other people where I can reciprocate with some review of my own. Oscar's altmap work looks like a good candidate for that.
I'm also hoping Jeff can give a tested-by for the customer scenarios that fall over with the current implementation.
Sure. I'll also have a look over the patches.
-Jeff