On Fri, Jun 07, 2024 at 10:37:09AM +0200, David Hildenbrand wrote: >Let's remove highmem special-casing from adjust_managed_page_count(), >to result in less confusion why memblock manually adjusts >totalram_pages, and __free_pages_core() only adjusts the zone's >managed pages -- what about the highmem pages that >adjust_managed_page_count() updates? > Thanks David I have looked into this function and willing to get rid of it, but not found a good way. Your change really look nice. >Now, we only maintain totalram_pages and a zone's managed pages >independent of highmem support. We can derive the number of highmem pages >simply by looking at the relevant zone's managed pages. I don't think >there is any particular fast path that needs a maximum-efficient >totalhigh_pages() implementation. > >Note that highmem memory is currently initialized using >free_highmem_page()->free_reserved_page(), not __free_pages_core(). In the >future we might want to also use __free_pages_core() to initialize >highmem memory, to make that less special, and consider moving >totalram_pages updates into __free_pages_core() [1], so we can just use >adjust_managed_page_count() in there as well. > >Booting a simple kernel in QEMU reveals no highmem accounting change: > >Before: > Memory: 3095448K/3145208K available (14802K kernel code, 2073K rwdata, > 5000K rodata, 740K init, 556K bss, 49760K reserved, 0K cma-reserved, > 2244488K highmem) > >After: > Memory: 3095276K/3145208K available (14802K kernel code, 2073K rwdata, > 5000K rodata, 740K init, 556K bss, 49932K reserved, 0K cma-reserved, > 2244488K highmem) > >[1] https://lkml.kernel.org/r/20240601133402.2675-1-richard.weiyang@xxxxxxxxx > >Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> >Cc: Wei Yang <richard.weiyang@xxxxxxxxx> > >David Hildenbrand (2): > mm/highmem: reimplement totalhigh_pages() by walking zones > mm/highmem: make nr_free_highpages() return "unsigned long" > > include/linux/highmem-internal.h | 17 ++++++----------- > include/linux/highmem.h | 2 +- > mm/highmem.c | 20 +++++++++++++++----- > mm/page_alloc.c | 4 ---- > 4 files changed, 22 insertions(+), 21 deletions(-) > > >base-commit: 19b8422c5bd56fb5e7085995801c6543a98bda1f >-- >2.45.1 -- Wei Yang Help you, Help me
