[PATCH] rmap 12 pgtable remove rmap

From: Hugh Dickins <hugh@veritas.com>

Remove the support for pte_chain rmap from page table initialization, just
continue to maintain nr_page_table_pages (but only for user page tables -
it also counted vmalloc page tables before, little need, and I'm unsure if
per-cpu stats are safe early enough on all arches).  mm/memory.c is the
only core file affected.

But ppc and ppc64 have found the old rmap page table initialization useful
to support their ptep_test_and_clear_young: so transfer rmap's
initialization to them (even on kernel page tables?  well, okay).

diff --git a/arch/arm/mm/mm-armv.c b/arch/arm/mm/mm-armv.c
index 3a4a7a537b9b7f0f25d2d4bbcc5a47474d6a7f4f..50c2c0f8d7177d3d8be8283e4e32a6acfc66913c 100644 (file)
--- a/arch/arm/mm/mm-armv.c
+++ b/arch/arm/mm/mm-armv.c
@@ -18,7 +18,6 @@
 
 #include <asm/pgalloc.h>
 #include <asm/page.h>
-#include <asm/rmap.h>
 #include <asm/io.h>
 #include <asm/setup.h>
 #include <asm/tlbflush.h>
@@ -231,7 +230,7 @@ void free_pgd_slow(pgd_t *pgd)
 
        pte = pmd_page(*pmd);
        pmd_clear(pmd);
-       pgtable_remove_rmap(pte);
+       dec_page_state(nr_page_table_pages);
        pte_free(pte);
        pmd_free(pmd);
 free:

diff --git a/arch/ppc/mm/pgtable.c b/arch/ppc/mm/pgtable.c
index b1b93fc18d4d9af5546bb8aaf0adb0f94b9b126a..04c1481277d635ce6416579b85ec275b684c3726 100644 (file)
--- a/arch/ppc/mm/pgtable.c
+++ b/arch/ppc/mm/pgtable.c
@@ -86,9 +86,14 @@ pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
        extern int mem_init_done;
        extern void *early_get_page(void);
 
-       if (mem_init_done)
+       if (mem_init_done) {
                pte = (pte_t *)__get_free_page(GFP_KERNEL|__GFP_REPEAT);
-       else
+               if (pte) {
+                       struct page *ptepage = virt_to_page(pte);
+                       ptepage->mapping = (void *) mm;
+                       ptepage->index = address & PMD_MASK;
+               }
+       } else
                pte = (pte_t *)early_get_page();
        if (pte)
                clear_page(pte);
@@ -97,7 +102,7 @@ pte_t *pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 
 struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
 {
-       struct page *pte;
+       struct page *ptepage;
 
 #ifdef CONFIG_HIGHPTE
        int flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_REPEAT;
@@ -105,10 +110,13 @@ struct page *pte_alloc_one(struct mm_struct *mm, unsigned long address)
        int flags = GFP_KERNEL | __GFP_REPEAT;
 #endif
 
-       pte = alloc_pages(flags, 0);
-       if (pte)
-               clear_highpage(pte);
-       return pte;
+       ptepage = alloc_pages(flags, 0);
+       if (ptepage) {
+               ptepage->mapping = (void *) mm;
+               ptepage->index = address & PMD_MASK;
+               clear_highpage(ptepage);
+       }
+       return ptepage;
 }
 
 void pte_free_kernel(pte_t *pte)
@@ -116,15 +124,17 @@ void pte_free_kernel(pte_t *pte)
 #ifdef CONFIG_SMP
        hash_page_sync();
 #endif
+       virt_to_page(pte)->mapping = NULL;
        free_page((unsigned long)pte);
 }
 
-void pte_free(struct page *pte)
+void pte_free(struct page *ptepage)
 {
 #ifdef CONFIG_SMP
        hash_page_sync();
 #endif
-       __free_page(pte);
+       ptepage->mapping = NULL;
+       __free_page(ptepage);
 }
 
 #ifndef CONFIG_44x

diff --git a/arch/ppc64/mm/hugetlbpage.c b/arch/ppc64/mm/hugetlbpage.c
index 393feec3af32ff83afa482c7164fb1e3969d0ab8..d660b0d28a9ce9a9bdf39adebfb212c20bc7721a 100644 (file)
--- a/arch/ppc64/mm/hugetlbpage.c
+++ b/arch/ppc64/mm/hugetlbpage.c
@@ -24,7 +24,6 @@
 #include <asm/machdep.h>
 #include <asm/cputable.h>
 #include <asm/tlb.h>
-#include <asm/rmap.h>
 
 #include <linux/sysctl.h>
 
@@ -214,7 +213,7 @@ static int prepare_low_seg_for_htlb(struct mm_struct *mm, unsigned long seg)
                }
                page = pmd_page(*pmd);
                pmd_clear(pmd);
-               pgtable_remove_rmap(page);
+               dec_page_state(nr_page_table_pages);
                pte_free_tlb(tlb, page);
        }
        tlb_finish_mmu(tlb, start, end);

diff --git a/arch/ppc64/mm/tlb.c b/arch/ppc64/mm/tlb.c
index 99be5d0d7835bb328833bf19f9c8055ced1509fa..b616f9a40586915ae4ccaba3e6971e750a11e653 100644 (file)
--- a/arch/ppc64/mm/tlb.c
+++ b/arch/ppc64/mm/tlb.c
@@ -31,7 +31,6 @@
 #include <asm/tlb.h>
 #include <asm/hardirq.h>
 #include <linux/highmem.h>
-#include <asm/rmap.h>
 
 DEFINE_PER_CPU(struct ppc64_tlb_batch, ppc64_tlb_batch);
 
@@ -59,7 +58,8 @@ void hpte_update(pte_t *ptep, unsigned long pte, int wrprot)
 
        ptepage = virt_to_page(ptep);
        mm = (struct mm_struct *) ptepage->mapping;
-       addr = ptep_to_address(ptep);
+       addr = ptepage->index +
+               (((unsigned long)ptep & ~PAGE_MASK) * PTRS_PER_PTE);
 
        if (REGION_ID(addr) == USER_REGION_ID)
                context = mm->context.id;

diff --git a/include/asm-ppc64/pgalloc.h b/include/asm-ppc64/pgalloc.h
index 251bbd9a535cc0971a63c22a48472b1fa574c69d..3a073a3c0e03108748b2e640da7fe2ccb80361dd 100644 (file)
--- a/include/asm-ppc64/pgalloc.h
+++ b/include/asm-ppc64/pgalloc.h
@@ -48,28 +48,43 @@ pmd_free(pmd_t *pmd)
        pmd_populate_kernel(mm, pmd, page_address(pte_page))
 
 static inline pte_t *
-pte_alloc_one_kernel(struct mm_struct *mm, unsigned long addr)
+pte_alloc_one_kernel(struct mm_struct *mm, unsigned long address)
 {
-       return kmem_cache_alloc(zero_cache, GFP_KERNEL|__GFP_REPEAT);
+       pte_t *pte;
+       pte = kmem_cache_alloc(zero_cache, GFP_KERNEL|__GFP_REPEAT);
+       if (pte) {
+               struct page *ptepage = virt_to_page(pte);
+               ptepage->mapping = (void *) mm;
+               ptepage->index = address & PMD_MASK;
+       }
+       return pte;
 }
 
 static inline struct page *
 pte_alloc_one(struct mm_struct *mm, unsigned long address)
 {
-       pte_t *pte = pte_alloc_one_kernel(mm, address);
-
-       if (pte)
-               return virt_to_page(pte);
-
+       pte_t *pte;
+       pte = kmem_cache_alloc(zero_cache, GFP_KERNEL|__GFP_REPEAT);
+       if (pte) {
+               struct page *ptepage = virt_to_page(pte);
+               ptepage->mapping = (void *) mm;
+               ptepage->index = address & PMD_MASK;
+               return ptepage;
+       }
        return NULL;
 }
                
 static inline void pte_free_kernel(pte_t *pte)
 {
+       virt_to_page(pte)->mapping = NULL;
        kmem_cache_free(zero_cache, pte);
 }
 
-#define pte_free(pte_page)     pte_free_kernel(page_address(pte_page))
+static inline void pte_free(struct page *ptepage)
+{
+       ptepage->mapping = NULL;
+       kmem_cache_free(zero_cache, page_address(ptepage));
+}
 
 struct pte_freelist_batch
 {

diff --git a/mm/memory.c b/mm/memory.c
index 1c385d7864554bfbfc6f289781c3f519eaea8b3c..1c2ce1f326e596f36a8b9f3d622368cea0bb9fcf 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -48,7 +48,6 @@
 #include <linux/init.h>
 
 #include <asm/pgalloc.h>
-#include <asm/rmap.h>
 #include <asm/uaccess.h>
 #include <asm/tlb.h>
 #include <asm/tlbflush.h>
@@ -105,7 +104,7 @@ static inline void free_one_pmd(struct mmu_gather *tlb, pmd_t * dir)
        }
        page = pmd_page(*dir);
        pmd_clear(dir);
-       pgtable_remove_rmap(page);
+       dec_page_state(nr_page_table_pages);
        pte_free_tlb(tlb, page);
 }
 
@@ -164,7 +163,7 @@ pte_t fastcall * pte_alloc_map(struct mm_struct *mm, pmd_t *pmd, unsigned long a
                        pte_free(new);
                        goto out;
                }
-               pgtable_add_rmap(new, mm, address);
+               inc_page_state(nr_page_table_pages);
                pmd_populate(mm, pmd, new);
        }
 out:
@@ -190,7 +189,6 @@ pte_t fastcall * pte_alloc_kernel(struct mm_struct *mm, pmd_t *pmd, unsigned lon
                        pte_free_kernel(new);
                        goto out;
                }
-               pgtable_add_rmap(virt_to_page(new), mm, address);
                pmd_populate_kernel(mm, pmd, new);
        }
 out: