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| author | Michal Hocko <mhocko@suse.com> | 2019-12-01 04:54:27 +0300 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-12-01 23:59:05 +0300 |
| commit | 09dbcf422e9b791d2d43cad8c283d9bdaef019a9 (patch) | |
| tree | a5028886e50f486626e2fa6414cc9b3b6deddbda /mm | |
| parent | 030eab4f9ffb469344c10a46bc02c5149db0a2a9 (diff) | |
| download | linux-09dbcf422e9b791d2d43cad8c283d9bdaef019a9.tar.xz | |
mm/sparse.c: do not waste pre allocated memmap space
Vincent has noticed [1] that there is something unusual with the memmap
allocations going on on his platform
: 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.
The underlying problem is that although sparse_buffer_init allocates
enough memory for all sections on the node sparse_buffer_alloc is not
able to consume them due to mismatch in the expected allocation
alignement. While sparse_buffer_init preallocation uses the PAGE_SIZE
alignment the real memmap has to be aligned to section_map_size() this
results in a wasted initial chunk of the preallocated memmap and
unnecessary fallback allocation for a section.
While we are at it also change __populate_section_memmap to align to the
requested size because at least VMEMMAP has constrains to have memmap
properly aligned.
[1] http://lkml.kernel.org/r/20191030131122.8256-1-vincent.whitchurch@axis.com
[akpm@linux-foundation.org: tweak layout, per David]
Link: http://lkml.kernel.org/r/20191119092642.31799-1-mhocko@kernel.org
Fixes: 35fd1eb1e821 ("mm/sparse: abstract sparse buffer allocations")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Debugged-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Oscar Salvador <OSalvador@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/sparse.c | 14 |
1 files changed, 8 insertions, 6 deletions
diff --git a/mm/sparse.c b/mm/sparse.c index 163b4d59cf6c..8526d3bf1e4e 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -458,8 +458,7 @@ struct page __init *__populate_section_memmap(unsigned long pfn, if (map) return map; - map = memblock_alloc_try_nid_raw(size, - PAGE_SIZE, addr, + map = memblock_alloc_try_nid_raw(size, size, addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid); if (!map) panic("%s: Failed to allocate %lu bytes align=0x%lx nid=%d from=%pa\n", @@ -482,10 +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()? */ - sparsemap_buf = - memblock_alloc_try_nid_raw(size, PAGE_SIZE, - addr, - MEMBLOCK_ALLOC_ACCESSIBLE, nid); + /* + * 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, section_map_size(), + addr, MEMBLOCK_ALLOC_ACCESSIBLE, nid); sparsemap_buf_end = sparsemap_buf + size; } |