On Mon, May 17, 2021 at 07:20:42PM +0800, Dong Aisheng wrote:
> The only path to call memory_present() is from memblocks_present().
> The struct mem_section **mem_section only needs to be initialized once,
> so no need put the initialization/allocation code in memory_present()
> which will be called multiple times for each section.
>
> After moving, the 'unlikely' condition statement becomes to be
> meaningless as it's only initialized one time, so dropped as well.
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>
> ---
> mm/sparse.c | 23 ++++++++++-------------
> 1 file changed, 10 insertions(+), 13 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 98bfacc763da..df4418c12f04 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -254,19 +254,6 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
> {
> unsigned long pfn;
>
> -#ifdef CONFIG_SPARSEMEM_EXTREME
> - if (unlikely(!mem_section)) {
> - unsigned long size, align;
> -
> - size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
> - align = 1 << (INTERNODE_CACHE_SHIFT);
> - mem_section = memblock_alloc(size, align);
> - if (!mem_section)
> - panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
> - __func__, size, align);
> - }
> -#endif
Maybe split this into a helper function and call it directly from
sparse_init()?
> -
> start &= PAGE_SECTION_MASK;
> mminit_validate_memmodel_limits(&start, &end);
> for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
> @@ -292,9 +279,19 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
> */
> static void __init memblocks_present(void)
> {
> + unsigned long __maybe_unused size, align;
> unsigned long start, end;
> int i, nid;
>
> +#ifdef CONFIG_SPARSEMEM_EXTREME
> + size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
> + align = 1 << (INTERNODE_CACHE_SHIFT);
> + mem_section = memblock_alloc(size, align);
> + if (!mem_section)
> + panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
> + __func__, size, align);
> +#endif
> +
> for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
> memory_present(nid, start, end);
> }
> --
> 2.25.1
>
>
--
Sincerely yours,
Mike.
