On Wed, Oct 30, 2019 at 02:11:22PM +0100, Vincent Whitchurch wrote: > sparsemem without VMEMMAP has two allocation paths to allocate the > memory needed for its memmap (done in sparse_mem_map_populate()). > > In one allocation path (sparse_buffer_alloc() succeeds), the memory is > not zeroed (since it was previously allocated with > memblock_alloc_try_nid_raw()). > > In the other allocation path (sparse_buffer_alloc() fails and > sparse_mem_map_populate() falls back to memblock_alloc_try_nid()), the > memory is zeroed. > > AFAICS this difference does not appear to be on purpose. If the code is > supposed to work with non-initialized memory (__init_single_page() takes > care of zeroing the struct pages which are actually used), we should > consistently not zero the memory, to avoid masking bugs. > > (I noticed this because on my ARM64 platform, with 1 GiB of memory the > first [and only] section is allocated from the zeroing path while with > 2 GiB of memory the first 1 GiB section is allocated from the > non-zeroing path.) > > Signed-off-by: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx> Good catch Reviewed-by: Oscar Salvador <osalvador@xxxxxxx> > --- > mm/sparse.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/sparse.c b/mm/sparse.c > index f6891c1992b1..01e467adc219 100644 > --- a/mm/sparse.c > +++ b/mm/sparse.c > @@ -458,7 +458,7 @@ struct page __init *__populate_section_memmap(unsigned long pfn, > if (map) > return map; > > - map = memblock_alloc_try_nid(size, > + map = memblock_alloc_try_nid_raw(size, > PAGE_SIZE, addr, > MEMBLOCK_ALLOC_ACCESSIBLE, nid); > if (!map) > -- > 2.20.0 > -- Oscar Salvador SUSE L3
