* Dong Aisheng <aisheng.dong@xxxxxxx> [210531 05:20]:
> 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>
> Cc: Mike Rapoport <rppt@xxxxxxxxxx>
> Signed-off-by: Dong Aisheng <aisheng.dong@xxxxxxx>
> ---
> ChangeLog:
> v1->v2:
> * split into a helper function and called directly from sparse_init
> ---
> mm/sparse.c | 29 ++++++++++++++++-------------
> 1 file changed, 16 insertions(+), 13 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 408b737e168e..d02ee6bb7cbc 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -60,6 +60,18 @@ static inline void set_section_nid(unsigned long section_nr, int nid)
> #endif
>
> #ifdef CONFIG_SPARSEMEM_EXTREME
> +static void __init sparse_alloc_section_roots(void)
> +{
> + 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);
> +}
> +
> static noinline struct mem_section __ref *sparse_index_alloc(int nid)
> {
> struct mem_section *section = NULL;
> @@ -107,6 +119,8 @@ static inline int sparse_index_init(unsigned long section_nr, int nid)
> {
> return 0;
> }
> +
> +static inline void sparse_alloc_section_roots(void) {}
> #endif
>
> #ifdef CONFIG_SPARSEMEM_EXTREME
> @@ -254,19 +268,6 @@ 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
> -
> start &= PAGE_SECTION_MASK;
> mminit_validate_memmodel_limits(&start, &end);
> for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION) {
> @@ -582,6 +583,8 @@ void __init sparse_init(void)
> unsigned long pnum_end, pnum_begin, map_count = 1;
> int nid_begin;
>
> + sparse_alloc_section_roots();
nit: The newline below is unnecessary
> +
> memblocks_present();
>
> pnum_begin = first_present_section_nr();
> --
> 2.25.1
>
>
