mm: sparse: pass section_nr to section_mark_present

Patch series "mm: sparse: remove __section_nr() function", v4.

This patch (of 3):

With CONFIG_SPARSEMEM_EXTREME enabled, __section_nr() which converts
mem_section to section_nr could be costly since it iterates all section
roots to check if the given mem_section is in its range.

Since both callers of section_mark_present already know section_nr, let's
also pass section_nr as well as mem_section in order to reduce costly
translation.

Link: https://lkml.kernel.org/r/20210707150212.855-1-ohoono.kwon@samsung.com
Link: https://lkml.kernel.org/r/20210707150212.855-2-ohoono.kwon@samsung.comSigned-off-by: Ohhoon Kwon <ohoono.kwon@samsung.com>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/sparse.c

@@ -187,10 +187,9 @@ void __meminit mminit_validate_memmodel_limits(unsigned long *start_pfn,
  * those loops early.
  */
 unsigned long __highest_present_section_nr;
-static void section_mark_present(struct mem_section *ms)
+static void __section_mark_present(struct mem_section *ms,
+		unsigned long section_nr)
 {
-	unsigned long section_nr = __section_nr(ms);
-
 	if (section_nr > __highest_present_section_nr)
 		__highest_present_section_nr = section_nr;
 
@@ -280,7 +279,7 @@ static void __init memory_present(int nid, unsigned long start, unsigned long en
 		if (!ms->section_mem_map) {
 			ms->section_mem_map = sparse_encode_early_nid(nid) |
 							SECTION_IS_ONLINE;
-			section_mark_present(ms);
+			__section_mark_present(ms, section);
 		}
 	}
 }
@@ -934,7 +933,7 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn,
 
 	ms = __nr_to_section(section_nr);
 	set_section_nid(section_nr, nid);
-	section_mark_present(ms);
+	__section_mark_present(ms, section_nr);
 
 	/* Align memmap to section boundary in the subsection case */
 	if (section_nr_to_pfn(section_nr) != start_pfn)