Re: [PATCH RFC 20/29] mm: convert "movable" flag in page->mapping to a page flag
From: Zi Yan <ziy@nvidia.com>
Date: 2025-06-23 14:14:23
Also in:
linux-fsdevel, linux-mm, linuxppc-dev, lkml, virtualization
On 18 Jun 2025, at 13:40, David Hildenbrand wrote:
Instead, let's use a page flag. As the page flag can result in false-positives, glue it to the page types for which we support/implement movable_ops page migration. Signed-off-by: David Hildenbrand <redacted> --- include/linux/balloon_compaction.h | 2 +- include/linux/migrate.h | 8 ----- include/linux/page-flags.h | 52 ++++++++++++++++++++++++------ mm/compaction.c | 6 ---- mm/zpdesc.h | 2 +- 5 files changed, 44 insertions(+), 26 deletions(-)
<snip>
+
+/**
+ * page_has_movable_ops - test for a movable_ops page
+ * @page The page to test.
+ *
+ * Test whether this is a movable_ops page. Such pages will stay that
+ * way until freed.
+ *
+ * Returns true if this is a movable_ops page, otherwise false.
+ */
+static inline bool page_has_movable_ops(const struct page *page)
+{
+ return PageMovableOps(page) &&
+ (PageOffline(page) || PageZsmalloc(page));
+}
+Should we do the code below in case PageMovableOps is set on pages other than PageOffline and PageZsmalloc? return PageMovableOps(page) && !VM_WARN_ON_ONCE_PAGE(!(PageOffline(page) || PageZsmalloc(page)), page);
quoted hunk ↗ jump to hunk
static __always_inline int PageAnonExclusive(const struct page *page) { VM_BUG_ON_PGFLAGS(!PageAnon(page), page);diff --git a/mm/compaction.c b/mm/compaction.c index a10f23df9396e..86d671a520e91 100644 --- a/mm/compaction.c +++ b/mm/compaction.c@@ -114,12 +114,6 @@ static unsigned long release_free_list(struct list_head *freepages) } #ifdef CONFIG_COMPACTION -void __SetPageMovable(struct page *page) -{ - VM_BUG_ON_PAGE(!PageLocked(page), page); - page->mapping = (void *)(PAGE_MAPPING_MOVABLE); -} -EXPORT_SYMBOL(__SetPageMovable); /* Do not skip compaction more than 64 times */ #define COMPACT_MAX_DEFER_SHIFT 6diff --git a/mm/zpdesc.h b/mm/zpdesc.h index 6855d9e2732d8..25bf5ea0beb83 100644 --- a/mm/zpdesc.h +++ b/mm/zpdesc.h@@ -154,7 +154,7 @@ static inline struct zpdesc *pfn_zpdesc(unsigned long pfn) static inline void __zpdesc_set_movable(struct zpdesc *zpdesc) { - __SetPageMovable(zpdesc_page(zpdesc)); + SetPageMovableOps(zpdesc_page(zpdesc)); } static inline void __zpdesc_set_zsmalloc(struct zpdesc *zpdesc)-- 2.49.0
Otherwise, LGTM. Reviewed-by: Zi Yan [off-list ref] -- Best Regards, Yan, Zi