On Mon, Sep 10, 2018 at 4:43 PM, Alexander Duyck <alexander.duyck@xxxxxxxxx> wrote: > > From: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > > The ZONE_DEVICE pages were being initialized in two locations. One was with > the memory_hotplug lock held and another was outside of that lock. The > problem with this is that it was nearly doubling the memory initialization > time. Instead of doing this twice, once while holding a global lock and > once without, I am opting to defer the initialization to the one outside of > the lock. This allows us to avoid serializing the overhead for memory init > and we can instead focus on per-node init times. > > One issue I encountered is that devm_memremap_pages and > hmm_devmmem_pages_create were initializing only the pgmap field the same > way. One wasn't initializing hmm_data, and the other was initializing it to > a poison value. Since this is something that is exposed to the driver in > the case of hmm I am opting for a third option and just initializing > hmm_data to 0 since this is going to be exposed to unknown third party > drivers. > > Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx> > --- > include/linux/mm.h | 2 + > kernel/memremap.c | 24 +++++--------- > mm/hmm.c | 12 ++++--- > mm/page_alloc.c | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++- Hmm, why mm/page_alloc.c and not kernel/memremap.c for this new helper? I think that would address the kbuild reports and keeps all the devm_memremap_pages / ZONE_DEVICE special casing centralized. I also think it makes sense to move memremap.c to mm/ rather than kernel/ especially since commit 5981690ddb8f "memremap: split devm_memremap_pages() and memremap() infrastructure". Arguably, that commit should have went ahead with the directory move.
