On Wed, Oct 30, 2019 at 2:01 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
>
> On Wed 30-10-19 13:53:52, Pavel Tatashin wrote:
> > On Wed, Oct 30, 2019 at 1:31 PM Michal Hocko <mhocko@xxxxxxxxxx> wrote:
> > >
> > > On Wed 30-10-19 12:53:41, Pavel Tatashin wrote:
> [...]
> > > > Yes, PMD_SIZE should be the alignment here. It just does not make
> > > > sense to align to size.
> > >
> > > What about this? It still aligns to the size but that should be
> > > correctly done to the section size level.
> > >
> > > diff --git a/mm/sparse.c b/mm/sparse.c
> > > index 72f010d9bff5..ab1e6175ac9a 100644
> > > --- a/mm/sparse.c
> > > +++ b/mm/sparse.c
> > > @@ -456,8 +456,7 @@ struct page __init *__populate_section_memmap(unsigned long pfn,
> > > if (map)
> > > return map;
> > >
> > > - map = memblock_alloc_try_nid(size,
> > > - PAGE_SIZE, addr,
> > > + map = memblock_alloc_try_nid(size, size, addr,
> > > MEMBLOCK_ALLOC_ACCESSIBLE, nid);
> > > if (!map)
> > > panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n",
> > > @@ -474,8 +473,13 @@ 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);
> > > sparsemap_buf_end = sparsemap_buf + size;
> >
> > This looks good, I think we should also change alignment in fallback
> > of vmemmap_alloc_block() to be
> > section_map_size().
> >
> > +++ b/mm/sparse-vmemmap.c
> > @@ -65,9 +65,10 @@ void * __meminit vmemmap_alloc_block(unsigned long
> > size, int node)
> > warned = true;
> > }
> > return NULL;
> > - } else
> > - return __earlyonly_bootmem_alloc(node, size, size,
> > + } else {
> > + return __earlyonly_bootmem_alloc(node, size, section_map_size(),
> > __pa(MAX_DMA_ADDRESS));
> > + }
> > }
>
> Are you sure? Doesn't this provide the proper alignement already? Most
> callers do PAGE_SIZE vmemmap_populate_hugepages PMD_SIZE so the
> resulting alignment looks good to me.
Nevermind, you are right. I tracked only one path, and forgot about
the normal PAGE_SIZE path.
Thank you,
Pasha
> --
> Michal Hocko
> SUSE Labs
