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.
Fixes: e9b61f19858a5 ("thp: reintroduce split_huge_page()")
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 4.8+
---
mm/huge_memory.c | 12 ++++++------
mm/rmap.c | 13 +++----------
2 files changed, 9 insertions(+), 16 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 55478ab3c83b..30100fac2341 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2350,7 +2350,7 @@ void vma_adjust_trans_huge(struct vm_area_struct *vma,
}
}
-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 *page)
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 page *page, struct list_head *list,
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 *page, struct list_head *list)
}
/*
- * 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 *page, struct list_head *list)
}
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 *page, struct list_head *list)
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;
}
diff --git a/mm/rmap.c b/mm/rmap.c
index 1e79fac3186b..85b7f9423352 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1627,16 +1627,9 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
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.
--
2.20.0.rc0.387.gc7a69e6b6c-goog
