On Tue 19-11-19 14:10:47, Andrew Morton wrote:
> On Tue, 19 Nov 2019 11:03:58 +0100 David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> > > @@ -482,8 +481,13 @@ static void __init sparse_buffer_init(unsigned long size, int nid)
> > > {
> > > phys_addr_t addr = __pa(MAX_DMA_ADDRESS);
> > > WARN_ON(sparsemap_buf); /* forgot to call sparse_buffer_fini()? */
> > > + /*
> > > + * Pre-allocated buffer is mainly used by __populate_section_memmap
> > > + * and we want it to be properly aligned to the section size - this is
> > > + * especially the case for VMEMMAP which maps memmap to PMDs
> > > + */
> > > sparsemap_buf =
> > > - memblock_alloc_try_nid_raw(size, PAGE_SIZE,
> > > + memblock_alloc_try_nid_raw(size, section_map_size(),
> > > addr,
> > > MEMBLOCK_ALLOC_ACCESSIBLE, nid);
> >
> > Wow, that alignment/layout gives me nightmares ^
> >
> > None of your business, though :)
>
> We're allowed to change it ;)
>
> --- a/mm/sparse.c~mm-sparse-do-not-waste-pre-allocated-memmap-space-fix
> +++ a/mm/sparse.c
> @@ -486,10 +486,8 @@ static void __init sparse_buffer_init(un
> * and we want it to be properly aligned to the section size - this is
> * especially the case for VMEMMAP which maps memmap to PMDs
> */
> - sparsemap_buf =
> - memblock_alloc_try_nid_raw(size, section_map_size(),
> - addr,
> - MEMBLOCK_ALLOC_ACCESSIBLE, nid);
> + sparsemap_buf = memblock_alloc_try_nid_raw(size, section_map_size(),
> + addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid);
> sparsemap_buf_end = sparsemap_buf + size;
> }
I didn't bother mostly because the creative code layout made the
intention of the patch more obvious. But if it saves from nightmares
then why not.
--
Michal Hocko
SUSE Labs
