[patch 047/156] mm,hwpoison: unify THP handling for hard and soft offline

[Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>]

From: Oscar Salvador <osalvador@xxxxxxx>
Subject: mm,hwpoison: unify THP handling for hard and soft offline

Place the THP's page handling in a helper and use it from both hard and
soft-offline machinery, so we get rid of some duplicated code.

Link: https://lkml.kernel.org/r/20200922135650.1634-8-osalvador@xxxxxxx
Signed-off-by: Oscar Salvador <osalvador@xxxxxxx>
Acked-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Cc: Aristeu Rozanski <aris@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Dmitry Yakunin <zeil@xxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxxx>
Cc: Qian Cai <cai@xxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/memory-failure.c |   48 +++++++++++++++++++-----------------------
 1 file changed, 22 insertions(+), 26 deletions(-)

--- a/mm/memory-failure.c~mmhwpoison-unify-thp-handling-for-hard-and-soft-offline
+++ a/mm/memory-failure.c
@@ -1102,6 +1102,25 @@ static int identify_page_state(unsigned
 	return page_action(ps, p, pfn);
 }
 
+static int try_to_split_thp_page(struct page *page, const char *msg)
+{
+	lock_page(page);
+	if (!PageAnon(page) || unlikely(split_huge_page(page))) {
+		unsigned long pfn = page_to_pfn(page);
+
+		unlock_page(page);
+		if (!PageAnon(page))
+			pr_info("%s: %#lx: non anonymous thp\n", msg, pfn);
+		else
+			pr_info("%s: %#lx: thp split failed\n", msg, pfn);
+		put_page(page);
+		return -EBUSY;
+	}
+	unlock_page(page);
+
+	return 0;
+}
+
 static int memory_failure_hugetlb(unsigned long pfn, int flags)
 {
 	struct page *p = pfn_to_page(pfn);
@@ -1324,21 +1343,8 @@ int memory_failure(unsigned long pfn, in
 	}
 
 	if (PageTransHuge(hpage)) {
-		lock_page(p);
-		if (!PageAnon(p) || unlikely(split_huge_page(p))) {
-			unlock_page(p);
-			if (!PageAnon(p))
-				pr_err("Memory failure: %#lx: non anonymous thp\n",
-					pfn);
-			else
-				pr_err("Memory failure: %#lx: thp split failed\n",
-					pfn);
-			if (TestClearPageHWPoison(p))
-				num_poisoned_pages_dec();
-			put_page(p);
+		if (try_to_split_thp_page(p, "Memory Failure") < 0)
 			return -EBUSY;
-		}
-		unlock_page(p);
 		VM_BUG_ON_PAGE(!page_count(p), p);
 	}
 
@@ -1855,19 +1861,9 @@ static int soft_offline_in_use_page(stru
 	int mt;
 	struct page *hpage = compound_head(page);
 
-	if (!PageHuge(page) && PageTransHuge(hpage)) {
-		lock_page(page);
-		if (!PageAnon(page) || unlikely(split_huge_page(page))) {
-			unlock_page(page);
-			if (!PageAnon(page))
-				pr_info("soft offline: %#lx: non anonymous thp\n", page_to_pfn(page));
-			else
-				pr_info("soft offline: %#lx: thp split failed\n", page_to_pfn(page));
-			put_page(page);
+	if (!PageHuge(page) && PageTransHuge(hpage))
+		if (try_to_split_thp_page(page, "soft offline") < 0)
 			return -EBUSY;
-		}
-		unlock_page(page);
-	}
 
 	/*
 	 * Setting MIGRATE_ISOLATE here ensures that the page will be linked
_