On 8/17/18 11:41 AM, Oscar Salvador wrote: > From: Oscar Salvador <osalvador@xxxxxxx> > > Currently, we decrement zone/node spanned_pages when we > remove memory and not when we offline it. > > This, besides of not being consistent with the current code, > implies that we can access steal pages if we never get to online > that memory. > > In order to prevent that, we have to move all zone/pages stuff to > the offlining memory stage. > Removing memory path should only care about memory sections and memory > blocks. > > Another thing to notice here is that this is not so easy to be done > as HMM/devm have a particular handling of memory-hotplug. > They do not go through the common path, and so, they do not > call either offline_pages() nor online_pages(). > > All they care about is to add the sections, move the pages to > ZONE_DEVICE, and in some cases, to create the linear mapping. > > In order to do this more smooth, two new functions are created > to deal with these particular cases: > > del_device_memory > add_device_memory > > add_device_memory is in charge of > > a) calling either arch_add_memory() or add_pages(), depending on whether > we want a linear mapping > b) online the memory sections that correspond to the pfn range > c) calling move_pfn_range_to_zone() being zone ZONE_DEVICE to > expand zone/pgdat spanned pages and initialize its pages > > del_device_memory, on the other hand, is in charge of > > a) offline the memory sections that correspond to the pfn range > b) calling shrink_pages(), which shrinks node/zone spanned pages. > c) calling either arch_remove_memory() or __remove_pages(), depending on > whether we need to tear down the linear mapping or not > > These two functions are called from: > > add_device_memory: > - devm_memremap_pages() > - hmm_devmem_pages_create() > > del_device_memory: > - devm_memremap_pages_release() > - hmm_devmem_release() > > I think that this will get easier as soon as [1] gets merged. > > Finally, shrink_pages() is moved to offline_pages(), so now, > all pages/zone handling is being taken care in online/offline_pages stage. > > [1] https://lkml.org/lkml/2018/6/19/110 > > Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> > --- > arch/ia64/mm/init.c | 4 +- > arch/powerpc/mm/mem.c | 10 +-- > arch/sh/mm/init.c | 4 +- > arch/x86/mm/init_32.c | 4 +- > arch/x86/mm/init_64.c | 8 +-- > include/linux/memory_hotplug.h | 9 ++- > kernel/memremap.c | 14 ++-- > kernel/resource.c | 16 +++++ > mm/hmm.c | 32 ++++----- > mm/memory_hotplug.c | 143 +++++++++++++++++++++++++++-------------- > mm/sparse.c | 4 +- > 11 files changed, 145 insertions(+), 103 deletions(-) Hi Oscar, I have been studying this patch, and do not see anything bad about it except that it begs to be split into smaller patches. I think you can send this work as a series without RFC if this patch is split into 3 or so patches. I will review that series. Thank you, Pavel
