Let's make it clearer that we are talking about movable_ops pages.

While at it, convert a VM_BUG_ON to a VM_WARN_ON_ONCE_PAGE.

Reviewed-by: Zi Yan <z...@nvidia.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoa...@oracle.com>
Reviewed-by: Harry Yoo <harry....@oracle.com>
Signed-off-by: David Hildenbrand <da...@redhat.com>
---
 include/linux/migrate.h    |  2 +-
 include/linux/page-flags.h |  2 +-
 mm/compaction.c            |  7 ++-----
 mm/memory-failure.c        |  4 ++--
 mm/memory_hotplug.c        | 10 ++++------
 mm/migrate.c               |  8 ++++----
 mm/page_alloc.c            |  2 +-
 mm/page_isolation.c        | 10 +++++-----
 8 files changed, 20 insertions(+), 25 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 25659a685e2aa..e04035f70e36f 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -115,7 +115,7 @@ static inline void __SetPageMovable(struct page *page,
 static inline
 const struct movable_operations *page_movable_ops(struct page *page)
 {
-       VM_BUG_ON(!__PageMovable(page));
+       VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
 
        return (const struct movable_operations *)
                ((unsigned long)page->mapping - PAGE_MAPPING_MOVABLE);
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 4fe5ee67535b2..c67163b73c5ec 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -750,7 +750,7 @@ static __always_inline bool __folio_test_movable(const 
struct folio *folio)
                        PAGE_MAPPING_MOVABLE;
 }
 
-static __always_inline bool __PageMovable(const struct page *page)
+static __always_inline bool page_has_movable_ops(const struct page *page)
 {
        return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) ==
                                PAGE_MAPPING_MOVABLE;
diff --git a/mm/compaction.c b/mm/compaction.c
index 5c37373017014..41fd6a1fe9a33 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1056,11 +1056,8 @@ isolate_migratepages_block(struct compact_control *cc, 
unsigned long low_pfn,
                 * Skip any other type of page
                 */
                if (!PageLRU(page)) {
-                       /*
-                        * __PageMovable can return false positive so we need
-                        * to verify it under page_lock.
-                        */
-                       if (unlikely(__PageMovable(page)) &&
+                       /* Isolation code will deal with any races. */
+                       if (unlikely(page_has_movable_ops(page)) &&
                                        !PageIsolated(page)) {
                                if (locked) {
                                        unlock_page_lruvec_irqrestore(locked, 
flags);
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b91a33fb6c694..9e2cff1999347 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1388,8 +1388,8 @@ static inline bool HWPoisonHandlable(struct page *page, 
unsigned long flags)
        if (PageSlab(page))
                return false;
 
-       /* Soft offline could migrate non-LRU movable pages */
-       if ((flags & MF_SOFT_OFFLINE) && __PageMovable(page))
+       /* Soft offline could migrate movable_ops pages */
+       if ((flags & MF_SOFT_OFFLINE) && page_has_movable_ops(page))
                return true;
 
        return PageLRU(page) || is_free_buddy_page(page);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 62d45752f9f44..69a636e20f7bb 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1739,8 +1739,8 @@ bool mhp_range_allowed(u64 start, u64 size, bool 
need_mapping)
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 /*
- * Scan pfn range [start,end) to find movable/migratable pages (LRU pages,
- * non-lru movable pages and hugepages). Will skip over most unmovable
+ * Scan pfn range [start,end) to find movable/migratable pages (LRU and
+ * hugetlb folio, movable_ops pages). Will skip over most unmovable
  * pages (esp., pages that can be skipped when offlining), but bail out on
  * definitely unmovable pages.
  *
@@ -1759,13 +1759,11 @@ static int scan_movable_pages(unsigned long start, 
unsigned long end,
                struct folio *folio;
 
                page = pfn_to_page(pfn);
-               if (PageLRU(page))
-                       goto found;
-               if (__PageMovable(page))
+               if (PageLRU(page) || page_has_movable_ops(page))
                        goto found;
 
                /*
-                * PageOffline() pages that are not marked __PageMovable() and
+                * PageOffline() pages that do not have movable_ops and
                 * have a reference count > 0 (after MEM_GOING_OFFLINE) are
                 * definitely unmovable. If their reference count would be 0,
                 * they could at least be skipped when offlining memory.
diff --git a/mm/migrate.c b/mm/migrate.c
index 63a8c94c165e2..3be7a53c13b66 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -94,7 +94,7 @@ bool isolate_movable_ops_page(struct page *page, 
isolate_mode_t mode)
         * Note that once a page has movable_ops, it will stay that way
         * until the page was freed.
         */
-       if (unlikely(!__PageMovable(page)))
+       if (unlikely(!page_has_movable_ops(page)))
                goto out_putfolio;
 
        /*
@@ -111,7 +111,7 @@ bool isolate_movable_ops_page(struct page *page, 
isolate_mode_t mode)
        if (unlikely(!folio_trylock(folio)))
                goto out_putfolio;
 
-       VM_WARN_ON_ONCE_PAGE(!__PageMovable(page), page);
+       VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
        if (PageIsolated(page))
                goto out_no_isolated;
 
@@ -153,7 +153,7 @@ static void putback_movable_ops_page(struct page *page)
         */
        struct folio *folio = page_folio(page);
 
-       VM_WARN_ON_ONCE_PAGE(!__PageMovable(page), page);
+       VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(page), page);
        VM_WARN_ON_ONCE_PAGE(!PageIsolated(page), page);
        folio_lock(folio);
        page_movable_ops(page)->putback_page(page);
@@ -192,7 +192,7 @@ static int migrate_movable_ops_page(struct page *dst, 
struct page *src,
 {
        int rc = MIGRATEPAGE_SUCCESS;
 
-       VM_WARN_ON_ONCE_PAGE(!__PageMovable(src), src);
+       VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(src), src);
        VM_WARN_ON_ONCE_PAGE(!PageIsolated(src), src);
        rc = page_movable_ops(src)->migrate_page(dst, src, mode);
        if (rc == MIGRATEPAGE_SUCCESS)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index b825f224af01f..4aefeb2ae927f 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2006,7 +2006,7 @@ static bool prep_move_freepages_block(struct zone *zone, 
struct page *page,
                         * migration are movable. But we don't actually try
                         * isolating, as that would be expensive.
                         */
-                       if (PageLRU(page) || __PageMovable(page))
+                       if (PageLRU(page) || page_has_movable_ops(page))
                                (*num_movable)++;
                        pfn++;
                }
diff --git a/mm/page_isolation.c b/mm/page_isolation.c
index ece3bfc56bcd5..b97b965b3ed01 100644
--- a/mm/page_isolation.c
+++ b/mm/page_isolation.c
@@ -21,9 +21,9 @@
  * consequently belong to a single zone.
  *
  * PageLRU check without isolation or lru_lock could race so that
- * MIGRATE_MOVABLE block might include unmovable pages. And __PageMovable
- * check without lock_page also may miss some movable non-lru pages at
- * race condition. So you can't expect this function should be exact.
+ * MIGRATE_MOVABLE block might include unmovable pages. Similarly, pages
+ * with movable_ops can only be identified some time after they were
+ * allocated. So you can't expect this function should be exact.
  *
  * Returns a page without holding a reference. If the caller wants to
  * dereference that page (e.g., dumping), it has to make sure that it
@@ -133,7 +133,7 @@ static struct page *has_unmovable_pages(unsigned long 
start_pfn, unsigned long e
                if ((mode == PB_ISOLATE_MODE_MEM_OFFLINE) && PageOffline(page))
                        continue;
 
-               if (__PageMovable(page) || PageLRU(page))
+               if (PageLRU(page) || page_has_movable_ops(page))
                        continue;
 
                /*
@@ -421,7 +421,7 @@ static int isolate_single_pageblock(unsigned long 
boundary_pfn,
                         * proper free and split handling for them.
                         */
                        VM_WARN_ON_ONCE_PAGE(PageLRU(page), page);
-                       VM_WARN_ON_ONCE_PAGE(__PageMovable(page), page);
+                       VM_WARN_ON_ONCE_PAGE(page_has_movable_ops(page), page);
 
                        goto failed;
                }
-- 
2.49.0


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