On Thu, Apr 08, 2021 at 10:46:18AM +0530, Anshuman Khandual wrote:
>
>
> On 4/7/21 10:56 PM, Mike Rapoport wrote:
> > From: Mike Rapoport <r...@linux.ibm.com>
> >
> > The struct pages representing a reserved memory region are initialized
> > using reserve_bootmem_range() function. This function is called for each
> > reserved region just before the memory is freed from memblock to the buddy
> > page allocator.
> >
> > The struct pages for MEMBLOCK_NOMAP regions are kept with the default
> > values set by the memory map initialization which makes it necessary to
> > have a special treatment for such pages in pfn_valid() and
> > pfn_valid_within().
> >
> > Split out initialization of the reserved pages to a function with a
> > meaningful name and treat the MEMBLOCK_NOMAP regions the same way as the
> > reserved regions and mark struct pages for the NOMAP regions as
> > PageReserved.
>
> This would definitely need updating the comment for MEMBLOCK_NOMAP definition
> in include/linux/memblock.h just to make the semantics is clear,
Sure
> though arm64 is currently the only user for MEMBLOCK_NOMAP.
> > Signed-off-by: Mike Rapoport <r...@linux.ibm.com>
> > ---
> > mm/memblock.c | 23 +++++++++++++++++++++--
> > 1 file changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/mm/memblock.c b/mm/memblock.c
> > index afaefa8fc6ab..6b7ea9d86310 100644
> > --- a/mm/memblock.c
> > +++ b/mm/memblock.c
> > @@ -2002,6 +2002,26 @@ static unsigned long __init
> > __free_memory_core(phys_addr_t start,
> > return end_pfn - start_pfn;
> > }
> >
> > +static void __init memmap_init_reserved_pages(void)
> > +{
> > + struct memblock_region *region;
> > + phys_addr_t start, end;
> > + u64 i;
> > +
> > + /* initialize struct pages for the reserved regions */
> > + for_each_reserved_mem_range(i, &start, &end)
> > + reserve_bootmem_region(start, end);
> > +
> > + /* and also treat struct pages for the NOMAP regions as PageReserved */
> > + for_each_mem_region(region) {
> > + if (memblock_is_nomap(region)) {
> > + start = region->base;
> > + end = start + region->size;
> > + reserve_bootmem_region(start, end);
> > + }
> > + }
> > +}
> > +
> > static unsigned long __init free_low_memory_core_early(void)
> > {
> > unsigned long count = 0;
> > @@ -2010,8 +2030,7 @@ static unsigned long __init
> > free_low_memory_core_early(void)
> >
> > memblock_clear_hotplug(0, -1);
> >
> > - for_each_reserved_mem_range(i, &start, &end)
> > - reserve_bootmem_region(start, end);
> > + memmap_init_reserved_pages();
> >
> > /*
> > * We need to use NUMA_NO_NODE instead of NODE_DATA(0)->node_id
> >
--
Sincerely yours,
Mike.
