Re: [PATCH] mm/isolation: Remove redundant pfn_valid_within() in __first_valid_page()

From: Zi Yan
Date: Thu Mar 21 2019 - 01:02:03 EST


On 20 Mar 2019, at 21:13, Anshuman Khandual wrote:

pfn_valid_within() calls pfn_valid() when CONFIG_HOLES_IN_ZONE making it
redundant for both definitions (w/wo CONFIG_MEMORY_HOTPLUG) of the helper
pfn_to_online_page() which either calls pfn_valid() or pfn_valid_within().
pfn_valid_within() being 1 when !CONFIG_HOLES_IN_ZONE is irrelevant either
way. This does not change functionality.

Fixes: 2ce13640b3f4 ("mm: __first_valid_page skip over offline pages")

I would not say this patch fixes the commit 2ce13640b3f4 from 2017,
because the pfn_valid_within() in pfn_to_online_page() was introduced by
a recent commit b13bc35193d9e last month. :)

Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
mm/page_isolation.c | 2 --
1 file changed, 2 deletions(-)

diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index ce323e56b34d..d9b02bb13d60 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -150,8 +150,6 @@ __first_valid_page(unsigned long pfn, unsigned long nr_pages)
for (i = 0; i < nr_pages; i++) {
struct page *page;

- if (!pfn_valid_within(pfn + i))
- continue;
page = pfn_to_online_page(pfn + i);
if (!page)
continue;

This makes sense to me. You can add Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>.

--
Best Regards,
Yan Zi