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mm/huge_memory: rename freeze_page() to unmap_page()

PATCH New [email protected] 1 participant 1 message Dec 1, 2018

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PATCH 21/31 mm/huge_memory: rename freeze_page() to unmap_page()

From: Hugh Dickins <[email protected]>
Subject: mm/huge_memory: rename freeze_page() to unmap_page()

The term "freeze" is used in several ways in the kernel, and in mm it has the particular meaning of forcing page refcount temporarily to 0. freeze_page() is just too confusing a name for a function that unmaps a
page: rename it unmap_page(), and rename unfreeze_page() remap_page().

Went to change the mention of freeze_page() added later in mm/rmap.c, but found it to be incorrect: ordinary page reclaim reaches there too; but the substance of the comment still seems correct, so edit it down.

Link http://lkml.kernel.org/r/[email protected] open here
Fixes e9b61f19858a5 ("thp: reintroduce split_huge_page()")
Signed-off-by Hugh Dickins <[email protected]>
Acked-by Kirill A. Shutemov <[email protected]>
Cc Jerome Glisse <[email protected]>
Cc Konstantin Khlebnikov <[email protected]>
Cc Matthew Wilcox <[email protected]>
Cc <[email protected]> [4.8+]
Signed-off-by Andrew Morton <[email protected]>

---

 mm/huge_memory.c |   12 ++++++------
 mm/rmap.c        |   13 +++----------
 2 files changed, 9 insertions(+), 16 deletions(-)
mm/huge_memory.c renamed from mm/huge_memory.c~mm-huge_memory-rename-freeze_page-to-unmap_page +6 -6
@@ -2350,7 +2350,7 @@ void vma_adjust_trans_huge(struct vm_are
 	}
 }
 
-static void freeze_page(struct page *page)
+static void unmap_page(struct page *page)
 {
 	enum ttu_flags ttu_flags = TTU_IGNORE_MLOCK | TTU_IGNORE_ACCESS |
 		TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD;

@@ -2365,7 +2365,7 @@ static void freeze_page(struct page *pag
 	VM_BUG_ON_PAGE(!unmap_success, page);
 }
 
-static void unfreeze_page(struct page *page)
+static void remap_page(struct page *page)
 {
 	int i;
 	if (PageTransHuge(page)) {

@@ -2483,7 +2483,7 @@ static void __split_huge_page(struct pag
 
 	spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
 
-	unfreeze_page(head);
+	remap_page(head);
 
 	for (i = 0; i < HPAGE_PMD_NR; i++) {
 		struct page *subpage = head + i;

@@ -2664,7 +2664,7 @@ int split_huge_page_to_list(struct page
 	}
 
 	/*
-	 * Racy check if we can split the page, before freeze_page() will
+	 * Racy check if we can split the page, before unmap_page() will
 	 * split PMDs
 	 */
 	if (!can_split_huge_page(head, &extra_pins)) {

@@ -2673,7 +2673,7 @@ int split_huge_page_to_list(struct page
 	}
 
 	mlocked = PageMlocked(page);
-	freeze_page(head);
+	unmap_page(head);
 	VM_BUG_ON_PAGE(compound_mapcount(head), head);
 
 	/* Make sure the page is not on per-CPU pagevec as it takes pin */

@@ -2727,7 +2727,7 @@ int split_huge_page_to_list(struct page
 fail:		if (mapping)
 			xa_unlock(&mapping->i_pages);
 		spin_unlock_irqrestore(zone_lru_lock(page_zone(head)), flags);
-		unfreeze_page(head);
+		remap_page(head);
 		ret = -EBUSY;
 	}
mm/rmap.c renamed from mm/rmap.c~mm-huge_memory-rename-freeze_page-to-unmap_page +3 -10
@@ -1627,16 +1627,9 @@ static bool try_to_unmap_one(struct page
 						      address + PAGE_SIZE);
 		} else {
 			/*
-			 * We should not need to notify here as we reach this
-			 * case only from freeze_page() itself only call from
-			 * split_huge_page_to_list() so everything below must
-			 * be true:
-			 *   - page is not anonymous
-			 *   - page is locked
-			 *
-			 * So as it is a locked file back page thus it can not
-			 * be remove from the page cache and replace by a new
-			 * page before mmu_notifier_invalidate_range_end so no
+			 * This is a locked file-backed page, thus it cannot
+			 * be removed from the page cache and replaced by a new
+			 * page before mmu_notifier_invalidate_range_end, so no
 			 * concurrent thread might update its page table to
 			 * point at new page while a device still is using this
 			 * page.

_