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| author |   Vincent Whitchurch <vincent.whitchurch@axis.com> | 2019-11-30 17:54:20 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2019-12-01 12:59:05 -0800 |
| commit | 4c29700ed9908c15feeb84a40a415f4e921c5a66 (patch) | |
| tree | 1df623783aa5d3443eec55681d02c8f29a0675d9 /mm/sparse.c | |
| parent | mm/memory_hotplug.c: don't allow to online/offline memory blocks with holes (diff) | |
| download | linux-dev-4c29700ed9908c15feeb84a40a415f4e921c5a66.tar.xz linux-dev-4c29700ed9908c15feeb84a40a415f4e921c5a66.zip | |
mm/sparse: consistently do not zero memmap
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. )
Michal:
"the main user visible problem is a memory wastage. The overal amount
of memory should be small. I wouldn't call it stable material."
Link: http://lkml.kernel.org/r/20191030131122.8256-1-vincent.whitchurch@axis.com
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pavel Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/sparse.c')
| -rw-r--r-- | mm/sparse.c | 2 |
1 files changed, 1 insertions, 1 deletions
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) |