mm/huge_memory: minor cleanup for split_huge_pages_all

[ Upstream commit a17206dac7b262e7abed5a05e34a6bd6bd0a9b06 ]

There is nothing to do if a zone doesn't have any pages managed by the
buddy allocator. So we should check managed_zone instead. Also if a thp
is found, there's no need to traverse the subpages again.

Link: https://lkml.kernel.org/r/20220704132201.14611-13-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 2b7aa91ba0e8 ("mm/huge_memory: use pfn_to_online_page() in split_huge_pages_all()")
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 8cc150a..34d2979 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2879,9 +2879,12 @@ static void split_huge_pages_all(void)
        unsigned long total = 0, split = 0;
 
        pr_debug("Split all THPs\n");
-       for_each_populated_zone(zone) {
+       for_each_zone(zone) {
+               if (!managed_zone(zone))
+                       continue;
                max_zone_pfn = zone_end_pfn(zone);
                for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++) {
+                       int nr_pages;
                        if (!pfn_valid(pfn))
                                continue;
 
@@ -2897,8 +2900,10 @@ static void split_huge_pages_all(void)
 
                        total++;
                        lock_page(page);
+                       nr_pages = thp_nr_pages(page);
                        if (!split_huge_page(page))
                                split++;
+                       pfn += nr_pages - 1;
                        unlock_page(page);
 next:
                        put_page(page);