[patch 080/158] mm/page_isolation.c: convert SKIP_HWPOISON to MEMORY_OFFLINE

[patch 080/158] mm/page_isolation.c: convert SKIP_HWPOISON to MEMORY_OFFLINE

[akpm]

From: David Hildenbrand <david@redhat.com>
Subject: mm/page_isolation.c: convert SKIP_HWPOISON to MEMORY_OFFLINE

We have two types of users of page isolation:
1. Memory offlining: Offline memory so it can be unplugged. Memory won't
		     be touched.
2. Memory allocation: Allocate memory (e.g., alloc_contig_range()) to
		      become the owner of the memory and make use of it.

For example, in case we want to offline memory, we can ignore (skip over)
PageHWPoison() pages, as the memory won't get used.  We can allow to
offline memory.  In contrast, we don't want to allow to allocate such
memory.

Let's generalize the approach so we can special case other types of pages
we want to skip over in case we offline memory.  While at it, also pass
the same flags to test_pages_isolated().

Link: http://lkml.kernel.org/r/20191021172353.3056-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Suggested-by: Michal Hocko <mhocko@suse.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Pingfan Liu <kernelfans@gmail.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Pavel Tatashin <pasha.tatashin@soleen.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/page-isolation.h |    4 ++--
 mm/memory_hotplug.c            |    8 +++++---
 mm/page_alloc.c                |    4 ++--
 mm/page_isolation.c            |   12 ++++++------
 4 files changed, 15 insertions(+), 13 deletions(-)

--- a/include/linux/page-isolation.h~mm-page_isolationc-convert-skip_hwpoison-to-memory_offline
+++ a/include/linux/page-isolation.h
@@ -30,7 +30,7 @@ static inline bool is_migrate_isolate(in
 }
 #endif
 
-#define SKIP_HWPOISON	0x1
+#define MEMORY_OFFLINE	0x1
 #define REPORT_FAILURE	0x2
 
 bool has_unmovable_pages(struct zone *zone, struct page *page, int count,
@@ -58,7 +58,7 @@ undo_isolate_page_range(unsigned long st
  * Test all pages in [start_pfn, end_pfn) are isolated or not.
  */
 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
-			bool skip_hwpoisoned_pages);
+			int isol_flags);
 
 struct page *alloc_migrate_target(struct page *page, unsigned long private);
 
--- a/mm/memory_hotplug.c~mm-page_isolationc-convert-skip_hwpoison-to-memory_offline
+++ a/mm/memory_hotplug.c
@@ -1187,7 +1187,8 @@ static bool is_pageblock_removable_noloc
 	if (!zone_spans_pfn(zone, pfn))
 		return false;
 
-	return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE, SKIP_HWPOISON);
+	return !has_unmovable_pages(zone, page, 0, MIGRATE_MOVABLE,
+				    MEMORY_OFFLINE);
 }
 
 /* Checks if this range of memory is likely to be hot-removable. */
@@ -1402,7 +1403,8 @@ static int
 check_pages_isolated_cb(unsigned long start_pfn, unsigned long nr_pages,
 			void *data)
 {
-	return test_pages_isolated(start_pfn, start_pfn + nr_pages, true);
+	return test_pages_isolated(start_pfn, start_pfn + nr_pages,
+				   MEMORY_OFFLINE);
 }
 
 static int __init cmdline_parse_movable_node(char *p)
@@ -1513,7 +1515,7 @@ static int __ref __offline_pages(unsigne
 	/* set above range as isolated */
 	ret = start_isolate_page_range(start_pfn, end_pfn,
 				       MIGRATE_MOVABLE,
-				       SKIP_HWPOISON | REPORT_FAILURE);
+				       MEMORY_OFFLINE | REPORT_FAILURE);
 	if (ret < 0) {
 		reason = "failure to isolate range";
 		goto failed_removal;
--- a/mm/page_alloc.c~mm-page_isolationc-convert-skip_hwpoison-to-memory_offline
+++ a/mm/page_alloc.c
@@ -8261,7 +8261,7 @@ bool has_unmovable_pages(struct zone *zo
 		 * The HWPoisoned page may be not in buddy system, and
 		 * page_count() is not 0.
 		 */
-		if ((flags & SKIP_HWPOISON) && PageHWPoison(page))
+		if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
 			continue;
 
 		if (__PageMovable(page))
@@ -8477,7 +8477,7 @@ int alloc_contig_range(unsigned long sta
 	}
 
 	/* Make sure the range is really isolated. */
-	if (test_pages_isolated(outer_start, end, false)) {
+	if (test_pages_isolated(outer_start, end, 0)) {
 		pr_info_ratelimited("%s: [%lx, %lx) PFNs busy\n",
 			__func__, outer_start, end);
 		ret = -EBUSY;
--- a/mm/page_isolation.c~mm-page_isolationc-convert-skip_hwpoison-to-memory_offline
+++ a/mm/page_isolation.c
@@ -168,7 +168,8 @@ __first_valid_page(unsigned long pfn, un
  * @migratetype:	Migrate type to set in error recovery.
  * @flags:		The following flags are allowed (they can be combined in
  *			a bit mask)
- *			SKIP_HWPOISON - ignore hwpoison pages
+ *			MEMORY_OFFLINE - isolate to offline (!allocate) memory
+ *					 e.g., skip over PageHWPoison() pages
  *			REPORT_FAILURE - report details about the failure to
  *			isolate the range
  *
@@ -257,7 +258,7 @@ void undo_isolate_page_range(unsigned lo
  */
 static unsigned long
 __test_page_isolated_in_pageblock(unsigned long pfn, unsigned long end_pfn,
-				  bool skip_hwpoisoned_pages)
+				  int flags)
 {
 	struct page *page;
 
@@ -274,7 +275,7 @@ __test_page_isolated_in_pageblock(unsign
 			 * simple way to verify that as VM_BUG_ON(), though.
 			 */
 			pfn += 1 << page_order(page);
-		else if (skip_hwpoisoned_pages && PageHWPoison(page))
+		else if ((flags & MEMORY_OFFLINE) && PageHWPoison(page))
 			/* A HWPoisoned page cannot be also PageBuddy */
 			pfn++;
 		else
@@ -286,7 +287,7 @@ __test_page_isolated_in_pageblock(unsign
 
 /* Caller should ensure that requested range is in a single zone */
 int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
-			bool skip_hwpoisoned_pages)
+			int isol_flags)
 {
 	unsigned long pfn, flags;
 	struct page *page;
@@ -308,8 +309,7 @@ int test_pages_isolated(unsigned long st
 	/* Check all pages are free or marked as ISOLATED */
 	zone = page_zone(page);
 	spin_lock_irqsave(&zone->lock, flags);
-	pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn,
-						skip_hwpoisoned_pages);
+	pfn = __test_page_isolated_in_pageblock(start_pfn, end_pfn, isol_flags);
 	spin_unlock_irqrestore(&zone->lock, flags);
 
 	trace_test_pages_isolated(start_pfn, end_pfn, pfn);
_