mm: add is_huge_zero_folio()

This is the folio equivalent of is_huge_zero_page().  It doesn't add any
efficiency, but it does prevent the caller from passing a tail page and
getting confused when the predicate returns false.

Link: https://lkml.kernel.org/r/20240326202833.523759-3-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/fs/proc/page.c b/fs/proc/page.c
index 05120263af2a4406f56399d27db0bb02f65ffe1f..2fb64bdb64eb1d39926bad09264bb408ecde9459 100644 (file)
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -155,7 +155,7 @@ u64 stable_page_flags(const struct page *page)
        else if (folio_test_large(folio)) {
                if ((k & (1 << PG_lru)) || is_anon)
                        u |= 1 << KPF_THP;
-               else if (is_huge_zero_page(&folio->page)) {
+               else if (is_huge_zero_folio(folio)) {
                        u |= 1 << KPF_ZERO_PAGE;
                        u |= 1 << KPF_THP;
                }

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 1540a1481daf590961b2deab11298ad9a31a60fb..600c6008262b2e020513b58defd98dd1f646cc53 100644 (file)
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -356,6 +356,11 @@ static inline bool is_huge_zero_page(const struct page *page)
        return READ_ONCE(huge_zero_page) == page;
 }
 
+static inline bool is_huge_zero_folio(const struct folio *folio)
+{
+       return READ_ONCE(huge_zero_page) == &folio->page;
+}
+
 static inline bool is_huge_zero_pmd(pmd_t pmd)
 {
        return pmd_present(pmd) && READ_ONCE(huge_zero_pfn) == pmd_pfn(pmd);
@@ -485,6 +490,11 @@ static inline bool is_huge_zero_page(const struct page *page)
        return false;
 }
 
+static inline bool is_huge_zero_folio(const struct folio *folio)
+{
+       return false;
+}
+
 static inline bool is_huge_zero_pmd(pmd_t pmd)
 {
        return false;

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 75ad971ca45ea9c883fbaafafbf36083f70a5f2f..5c043c7b506244697be921cb65d6f6b7e035f4f7 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -789,12 +789,12 @@ struct deferred_split *get_deferred_split_queue(struct folio *folio)
 }
 #endif
 
-static inline bool is_transparent_hugepage(struct folio *folio)
+static inline bool is_transparent_hugepage(const struct folio *folio)
 {
        if (!folio_test_large(folio))
                return false;
 
-       return is_huge_zero_page(&folio->page) ||
+       return is_huge_zero_folio(folio) ||
                folio_test_large_rmappable(folio);
 }
 
@@ -3085,7 +3085,7 @@ int split_huge_page_to_list_to_order(struct page *page, struct list_head *list,
        }
 
 
-       is_hzp = is_huge_zero_page(&folio->page);
+       is_hzp = is_huge_zero_folio(folio);
        if (is_hzp) {
                pr_warn_ratelimited("Called split_huge_page for huge zero page\n");
                return -EBUSY;

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 913cff5da5a30c5f5d7246cd6e2a80ed09b6dd28..5743028a63a511b66e8e066708a23d56bcc57d93 100644 (file)
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -510,7 +510,7 @@ static void queue_folios_pmd(pmd_t *pmd, struct mm_walk *walk)
                return;
        }
        folio = pfn_folio(pmd_pfn(*pmd));
-       if (is_huge_zero_page(&folio->page)) {
+       if (is_huge_zero_folio(folio)) {
                walk->action = ACTION_CONTINUE;
                return;
        }

diff --git a/mm/swap.c b/mm/swap.c
index 500a09a48dfd3afe33f06722305532d325e43727..f72364e92d5f4f2220c2bbab7dc936d5c1ea110e 100644 (file)
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -985,7 +985,7 @@ void folios_put_refs(struct folio_batch *folios, unsigned int *refs)
                struct folio *folio = folios->folios[i];
                unsigned int nr_refs = refs ? refs[i] : 1;
 
-               if (is_huge_zero_page(&folio->page))
+               if (is_huge_zero_folio(folio))
                        continue;
 
                if (folio_is_zone_device(folio)) {

diff --git a/mm/swap_state.c b/mm/swap_state.c
index bfc7e8c58a6d34b948d73916ccd9bf0f1be14e21..2deac23633cdd8ed74e69614b28b37a249b17eec 100644 (file)
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -301,7 +301,7 @@ void free_page_and_swap_cache(struct page *page)
        struct folio *folio = page_folio(page);
 
        free_swap_cache(folio);
-       if (!is_huge_zero_page(page))
+       if (!is_huge_zero_folio(folio))
                folio_put(folio);
 }
 

diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
index 3c3539c573e7fec47b2ac883e18d7644d40197c3..a0ec14553fbeaabda75c2816ec6acc3f90cdf699 100644 (file)
--- a/mm/userfaultfd.c
+++ b/mm/userfaultfd.c
@@ -1664,7 +1664,7 @@ ssize_t move_pages(struct userfaultfd_ctx *ctx, unsigned long dst_start,
                            !pmd_none(dst_pmdval)) {
                                struct folio *folio = pfn_folio(pmd_pfn(*src_pmd));
 
-                               if (!folio || (!is_huge_zero_page(&folio->page) &&
+                               if (!folio || (!is_huge_zero_folio(folio) &&
                                               !PageAnonExclusive(&folio->page))) {
                                        spin_unlock(ptl);
                                        err = -EBUSY;