mm: add large_rmappable page flag

Stored in the first tail page's flags, this flag replaces the destructor.
That removes the last of the destructors, so remove all references to
folio_dtor and compound_dtor.

Link: https://lkml.kernel.org/r/20230816151201.3655946-9-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst
index baa1c355741d15a8692a048b0d6565c94baf3ca8..3bd38ac0e7de742e3061aafeab93f0c23613fe6a 100644 (file)
--- a/Documentation/admin-guide/kdump/vmcoreinfo.rst
+++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst
@@ -141,8 +141,8 @@ nodemask_t
 The size of a nodemask_t type. Used to compute the number of online
 nodes.
 
-(page, flags|_refcount|mapping|lru|_mapcount|private|compound_dtor|compound_order|compound_head)
--------------------------------------------------------------------------------------------------
+(page, flags|_refcount|mapping|lru|_mapcount|private|compound_order|compound_head)
+----------------------------------------------------------------------------------
 
 User-space tools compute their values based on the offset of these
 variables. The variables are used when excluding unnecessary pages.

diff --git a/include/linux/mm.h b/include/linux/mm.h
index e241f5ee4dc4c4638d08943c91f5cd4dd5be1955..63d5737819735d600a9d28bbcd5e7c5891e5614d 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1239,19 +1239,6 @@ void folio_copy(struct folio *dst, struct folio *src);
 
 unsigned long nr_free_buffer_pages(void);
 
-enum compound_dtor_id {
-       COMPOUND_PAGE_DTOR,
-       TRANSHUGE_PAGE_DTOR,
-       NR_COMPOUND_DTORS,
-};
-
-static inline void folio_set_compound_dtor(struct folio *folio,
-               enum compound_dtor_id compound_dtor)
-{
-       VM_BUG_ON_FOLIO(compound_dtor >= NR_COMPOUND_DTORS, folio);
-       folio->_folio_dtor = compound_dtor;
-}
-
 void destroy_large_folio(struct folio *folio);
 
 /* Returns the number of bytes in this potentially compound page. */

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index de5ac95572c8180e7ed520d12612c61c12feea17..1c5c2349c18ea19de02b3c89afcce2d17a4e5505 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -264,7 +264,6 @@ static inline struct page *encoded_page_ptr(struct encoded_page *page)
  * @_refcount: Do not access this member directly.  Use folio_ref_count()
  *    to find how many references there are to this folio.
  * @memcg_data: Memory Control Group data.
- * @_folio_dtor: Which destructor to use for this folio.
  * @_folio_order: Do not use directly, call folio_order().
  * @_entire_mapcount: Do not use directly, call folio_entire_mapcount().
  * @_nr_pages_mapped: Do not use directly, call folio_mapcount().
@@ -318,7 +317,6 @@ struct folio {
                        unsigned long _flags_1;
                        unsigned long _head_1;
        /* public: */
-                       unsigned char _folio_dtor;
                        unsigned char _folio_order;
                        atomic_t _entire_mapcount;
                        atomic_t _nr_pages_mapped;

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index e9e7cc45352d43072b771447a8042a5b4cd9ccb8..85d54b6c9e0b693576b6f85fa63d0fcfe37d7605 100644 (file)
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -190,6 +190,7 @@ enum pageflags {
        /* At least one page in this folio has the hwpoison flag set */
        PG_has_hwpoisoned = PG_error,
        PG_hugetlb = PG_active,
+       PG_large_rmappable = PG_workingset, /* anon or file-backed */
 };
 
 #define PAGEFLAGS_MASK         ((1UL << NR_PAGEFLAGS) - 1)
@@ -806,6 +807,9 @@ static inline void ClearPageCompound(struct page *page)
        BUG_ON(!PageHead(page));
        ClearPageHead(page);
 }
+PAGEFLAG(LargeRmappable, large_rmappable, PF_SECOND)
+#else
+TESTPAGEFLAG_FALSE(LargeRmappable, large_rmappable)
 #endif
 
 #define PG_head_mask ((1UL << PG_head))
@@ -1077,7 +1081,8 @@ static __always_inline void __ClearPageAnonExclusive(struct page *page)
  * the CHECK_AT_FREE flags above, so need to be cleared.
  */
 #define PAGE_FLAGS_SECOND                                              \
-       (1UL << PG_has_hwpoisoned       | 1UL << PG_hugetlb)
+       (1UL << PG_has_hwpoisoned       | 1UL << PG_hugetlb |           \
+        1UL << PG_large_rmappable)
 
 #define PAGE_FLAGS_PRIVATE                             \
        (1UL << PG_private | 1UL << PG_private_2)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index dd5f87047d068c36fffc882b8f8b75771fcb8258..934dd86e19f594ab830f359cb88377819f8c71d3 100644 (file)
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -455,7 +455,6 @@ static int __init crash_save_vmcoreinfo_init(void)
        VMCOREINFO_OFFSET(page, lru);
        VMCOREINFO_OFFSET(page, _mapcount);
        VMCOREINFO_OFFSET(page, private);
-       VMCOREINFO_OFFSET(folio, _folio_dtor);
        VMCOREINFO_OFFSET(folio, _folio_order);
        VMCOREINFO_OFFSET(page, compound_head);
        VMCOREINFO_OFFSET(pglist_data, node_zones);

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 5817bf77f1f07c4f37d506a698a3da5e19ad5238..2fe1ea187b6b4555e852c95c5cf10091ec2156b9 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -581,7 +581,7 @@ void folio_prep_large_rmappable(struct folio *folio)
 {
        VM_BUG_ON_FOLIO(folio_order(folio) < 2, folio);
        INIT_LIST_HEAD(&folio->_deferred_list);
-       folio_set_compound_dtor(folio, TRANSHUGE_PAGE_DTOR);
+       folio_set_large_rmappable(folio);
 }
 
 static inline bool is_transparent_hugepage(struct page *page)
@@ -593,7 +593,7 @@ static inline bool is_transparent_hugepage(struct page *page)
 
        folio = page_folio(page);
        return is_huge_zero_page(&folio->page) ||
-              folio->_folio_dtor == TRANSHUGE_PAGE_DTOR;
+               folio_test_large_rmappable(folio);
 }
 
 static unsigned long __thp_get_unmapped_area(struct file *filp,

diff --git a/mm/internal.h b/mm/internal.h
index 30bbfcacc90964bab28433be1d78ce344c5a4afc..5c0daea731f34b64cb216c26fcd1a23234068662 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -419,7 +419,6 @@ static inline void prep_compound_head(struct page *page, unsigned int order)
 {
        struct folio *folio = (struct folio *)page;
 
-       folio_set_compound_dtor(folio, COMPOUND_PAGE_DTOR);
        folio_set_order(folio, order);
        atomic_set(&folio->_entire_mapcount, -1);
        atomic_set(&folio->_nr_pages_mapped, 0);

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d96dc6a3077a6d96b2ddb9e76412c4ae87d1f80a..452459836b7118954de3e346ee602aff7f84207e 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -572,9 +572,6 @@ static inline void free_the_page(struct page *page, unsigned int order)
  * The remaining PAGE_SIZE pages are called "tail pages". PageTail() is encoded
  * in bit 0 of page->compound_head. The rest of bits is pointer to head page.
  *
- * The first tail page's ->compound_dtor describes how to destroy the
- * compound page.
- *
  * The first tail page's ->compound_order holds the order of allocation.
  * This usage means that zero-order pages may not be compound.
  */
@@ -593,14 +590,12 @@ void prep_compound_page(struct page *page, unsigned int order)
 
 void destroy_large_folio(struct folio *folio)
 {
-       enum compound_dtor_id dtor = folio->_folio_dtor;
-
        if (folio_test_hugetlb(folio)) {
                free_huge_folio(folio);
                return;
        }
 
-       if (folio_test_transhuge(folio) && dtor == TRANSHUGE_PAGE_DTOR)
+       if (folio_test_large_rmappable(folio))
                folio_undo_large_rmappable(folio);
 
        mem_cgroup_uncharge(folio);