2.4.13-ac1

 mm

diff -u --new-file --recursive --exclude-from /usr/src/exclude linux.vanilla/mm/memory.c linux.ac/mm/memory.c
--- linux.vanilla/mm/memory.c   Thu Oct 25 16:26:39 2001
+++ linux.ac/mm/memory.c   Sun Oct 21 18:36:24 2001
@@ -71,27 +71,6 @@
 mem_map_t * mem_map;
 
 /*
- * Called by TLB shootdown 
- */
-void __free_pte(pte_t pte)
-{
-   struct page *page = pte_page(pte);
-   if ((!VALID_PAGE(page)) || PageReserved(page))
-      return;
-   /*
-    * free_page() used to be able to clear swap cache
-    * entries.  We may now have to do it manually.
-    */
-   if (page->mapping) {
-      if (pte_dirty(pte))
-         set_page_dirty(page);
-   }
-      
-   free_page_and_swap_cache(page);
-}
-
-
-/*
  * Note: this doesn't free the actual pages themselves. That
  * has been handled earlier when unmapping all the memory regions.
  */
@@ -125,10 +104,8 @@
    }
    pmd = pmd_offset(dir, 0);
    pgd_clear(dir);
-   for (j = 0; j < PTRS_PER_PMD ; j++) {
-      prefetchw(pmd+j+(PREFETCH_STRIDE/16));
+   for (j = 0; j < PTRS_PER_PMD ; j++)
       free_one_pmd(pmd+j);
-   }
    pmd_free(pmd);
 }
 
@@ -487,7 +464,7 @@
    iobuf->length = len;
    
    i = 0;
-   
+
    /* 
     * First of all, try to fault in all of the necessary pages
     */
@@ -731,6 +708,7 @@
    } while (address && (address < end));
 }
 
+/* mm->page_table_lock must be held */
 static inline int zeromap_pmd_range(struct mm_struct *mm, pmd_t * pmd, unsigned long address,
                                     unsigned long size, pgprot_t prot)
 {
@@ -810,6 +788,7 @@
    } while (address && (address < end));
 }
 
+/* mm->page_table_lock must be held */
 static inline int remap_pmd_range(struct mm_struct *mm, pmd_t * pmd, unsigned long address, unsigned long size,
    unsigned long phys_addr, pgprot_t prot)
 {
@@ -881,9 +860,10 @@
 /*
  * We hold the mm semaphore for reading and vma->vm_mm->page_table_lock
  */
-static inline void break_cow(struct vm_area_struct * vma, struct page * new_page, unsigned long address, 
+static inline void break_cow(struct vm_area_struct * vma, struct page *   old_page, struct page * new_page, unsigned long address, 
       pte_t *page_table)
 {
+   copy_cow_page(old_page,new_page,address);
    flush_page_to_ram(new_page);
    flush_cache_page(vma, address);
    establish_pte(vma, address, page_table, pte_mkwrite(pte_mkdirty(mk_pte(new_page, vma->vm_page_prot))));
@@ -916,7 +896,10 @@
    old_page = pte_page(pte);
    if (!VALID_PAGE(old_page))
       goto bad_wp_page;
-   
+
+   if (old_page == ZERO_PAGE(address))
+      goto copy;
+
    /*
     * We can avoid the copy if:
     * - we're the only user (count == 1)
@@ -939,15 +922,11 @@
          break;
       /* Recheck swapcachedness once the page is locked */
       can_reuse = exclusive_swap_page(old_page);
-      if (can_reuse)
-         delete_from_swap_cache(old_page);
       UnlockPage(old_page);
       if (!can_reuse)
          break;
       /* FallThrough */
    case 1:
-      if (PageReserved(old_page))
-         break;
       flush_cache_page(vma, address);
       establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
       return 1;   /* Minor fault */
@@ -956,23 +935,26 @@
    /*
     * Ok, we need to copy. Oh, well..
     */
-   page_cache_get(old_page);
+copy:    
+    set_pte(page_table, pte);
    spin_unlock(&mm->page_table_lock);
-
    new_page = alloc_page(GFP_HIGHUSER);
+   spin_lock(&mm->page_table_lock);
    if (!new_page)
-      goto no_mem;
-   copy_cow_page(old_page,new_page,address);
-   page_cache_release(old_page);
+      return -1;
 
    /*
     * Re-check the pte - we dropped the lock
     */
-   spin_lock(&mm->page_table_lock);
    if (pte_same(*page_table, pte)) {
+      /* We are changing the pte, so get rid of the old
+       * one to avoid races with the hardware, this really
+       * only affects the accessed bit here.
+       */
+      pte = ptep_get_and_clear(page_table);
       if (PageReserved(old_page))
          ++mm->rss;
-      break_cow(vma, new_page, address, page_table);
+      break_cow(vma, old_page, new_page, address, page_table);
 
       /* Free the old page.. */
       new_page = old_page;
@@ -983,10 +965,6 @@
 bad_wp_page:
    printk("do_wp_page: bogus page at address %08lx (page 0x%lx)\n",address,(unsigned long)old_page);
    return -1;
-no_mem:
-   page_cache_release(old_page);
-   spin_lock(&mm->page_table_lock);
-   return -1;
 }
 
 static void vmtruncate_list(struct vm_area_struct *mpnt, unsigned long pgoff)
@@ -1039,6 +1017,7 @@
       goto out_unlock;
 
    pgoff = (offset + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
    if (mapping->i_mmap != NULL)
       vmtruncate_list(mapping->i_mmap, pgoff);
    if (mapping->i_mmap_shared != NULL)
@@ -1048,8 +1027,10 @@
    spin_unlock(&mapping->i_shared_lock);
    truncate_inode_pages(mapping, offset);
    goto out_truncate;
-
+   
 do_expand:
+   if (offset > inode->i_sb->s_maxbytes)
+      goto out;
    limit = current->rlim[RLIMIT_FSIZE].rlim_cur;
    if (limit != RLIM_INFINITY) {
       if (inode->i_size >= limit) {
@@ -1062,15 +1043,24 @@
       }
    }
    inode->i_size = offset;
-
+   if (inode->i_op && inode->i_op->truncate)
+   {
+      /* This doesnt scale but it is meant to be a 2.4 invariant */
+      lock_kernel();
+      inode->i_op->truncate(inode);
+      unlock_kernel();
+   }
+   return 0;
+   
 out_truncate:
    if (inode->i_op && inode->i_op->truncate) {
       lock_kernel();
-      inode->i_op->truncate(inode);
+       inode->i_op->truncate(inode);
       unlock_kernel();
    }
-out:
    return 0;
+out:
+   return -EFBIG;
 }
 
 /* 
@@ -1090,10 +1080,6 @@
     */
    num = valid_swaphandles(entry, &offset);
    for (i = 0; i < num; offset++, i++) {
-      /* Don't block on I/O for read-ahead */
-      if (atomic_read(&nr_async_pages) >=
-          pager_daemon.swap_cluster << page_cluster)
-         break;
       /* Ok, do the async read-ahead now */
       new_page = read_swap_cache_async(SWP_ENTRY(SWP_TYPE(entry), offset));
       if (!new_page)
@@ -1103,10 +1089,6 @@
    return;
 }
 
-/* Swap 80% full? Release the pages as they are paged in.. */
-#define vm_swap_full() \
-   (swapper_space.nrpages*5 > total_swap_pages*4)
-
 /*
  * We hold the mm semaphore and the page_table_lock on entry and exit.
  */
@@ -1122,8 +1104,10 @@
    spin_unlock(&mm->page_table_lock);
    page = lookup_swap_cache(entry);
    if (!page) {
+      lock_kernel();
       swapin_readahead(entry);
       page = read_swap_cache_async(entry);
+      unlock_kernel();
       if (!page) {
          spin_lock(&mm->page_table_lock);
          /*
@@ -1160,13 +1144,24 @@
    pte = mk_pte(page, vma->vm_page_prot);
 
    swap_free(entry);
-   mark_page_accessed(page);
-   if (exclusive_swap_page(page)) {
-      if (write_access || vm_swap_full()) {
-         pte = pte_mkdirty(pte);
-         if (vma->vm_flags & VM_WRITE)
-            pte = pte_mkwrite(pte);
+   if (exclusive_swap_page(page)) {   
+      if (write_access)
+         pte = pte_mkwrite(pte_mkdirty(pte));
+      /*
+       * If swap space is getting low and we were the last user
+       * of this piece of swap space, we free this space so
+       * somebody else can be swapped out.
+       *
+       * We hold the page lock (required whenever adding to or
+       * removing from the swap cache), and the page_table_lock
+       * prevents concurrent swap_duplicate()s of this exclusive
+       * entry by try_to_swap_out() or fork's copy_page_range() -
+       * there's even a second level of protection, page lock
+       * prevents try_to_swap_out() and mmap_sem prevents do_fork().
+       */
+      if (vm_swap_full()) {
          delete_from_swap_cache(page);
+         pte = pte_mkdirty(pte);
       }
    }
    UnlockPage(page);
@@ -1198,18 +1193,16 @@
 
       /* Allocate our own private page. */
       spin_unlock(&mm->page_table_lock);
-
       page = alloc_page(GFP_HIGHUSER);
-      if (!page)
-         goto no_mem;
-      clear_user_highpage(page, addr);
-
       spin_lock(&mm->page_table_lock);
+      if (!page)
+         return -1;
       if (!pte_none(*page_table)) {
          page_cache_release(page);
          return 1;
       }
       mm->rss++;
+      clear_user_highpage(page, addr);
       flush_page_to_ram(page);
       entry = pte_mkwrite(pte_mkdirty(mk_pte(page, vma->vm_page_prot)));
    }
@@ -1219,10 +1212,6 @@
    /* No need to invalidate - it was non-present before */
    update_mmu_cache(vma, addr, entry);
    return 1;   /* Minor fault */
-
-no_mem:
-   spin_lock(&mm->page_table_lock);
-   return -1;
 }
 
 /*
@@ -1242,10 +1231,16 @@
 {
    struct page * new_page;
    pte_t entry;
-
+   int ret;
+   struct inode *inode = NULL;
+   
    if (!vma->vm_ops || !vma->vm_ops->nopage)
       return do_anonymous_page(mm, vma, page_table, write_access, address);
    spin_unlock(&mm->page_table_lock);
+   if (vma->vm_file && vma->vm_file->f_dentry)
+      inode = vma->vm_file->f_dentry->d_inode;
+   if (inode)
+      down_read(&inode->i_truncate_sem);
 
    /*
     * The third argument is "no_share", which tells the low-level code
@@ -1255,10 +1250,16 @@
    new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, (vma->vm_flags & VM_SHARED)?0:write_access);
 
    spin_lock(&mm->page_table_lock);
-   if (new_page == NULL)   /* no page was available -- SIGBUS */
-      return 0;
-   if (new_page == NOPAGE_OOM)
-      return -1;
+   if (new_page == NULL) {   /* no page was available -- SIGBUS */
+      ret = 0;
+      goto out;
+   }
+   
+   if (new_page == NOPAGE_OOM) {
+      ret =  -1;
+      goto out;
+   }
+   
    /*
     * This silly early PAGE_DIRTY setting removes a race
     * due to the bad i386 page protection. But it's valid
@@ -1284,12 +1285,17 @@
    } else {
       /* One of our sibling threads was faster, back out. */
       page_cache_release(new_page);
-      return 1;
+      ret = 1;
+      goto out;
    }
 
    /* no need to invalidate: a not-present page shouldn't be cached */
    update_mmu_cache(vma, address, entry);
-   return 2;   /* Major fault */
+   ret = 2;   /* Major fault */
+out:
+   if (inode)
+      up_read(&inode->i_truncate_sem);
+   return ret;
 }
 
 /*
@@ -1328,12 +1334,14 @@
       return do_swap_page(mm, vma, address, pte, entry, write_access);
    }
 
+   entry = ptep_get_and_clear(pte);
    if (write_access) {
       if (!pte_write(entry))
          return do_wp_page(mm, vma, address, pte, entry);
 
       entry = pte_mkdirty(entry);
    }
+
    entry = pte_mkyoung(entry);
    establish_pte(vma, address, pte, entry);
    return 1;
@@ -1394,7 +1402,7 @@
        * Because we dropped the lock, we should re-check the
        * entry, as somebody else could have populated it..
        */
-      if (!pgd_none(*pgd)) {
+      if (pgd_present(*pgd)) {
          pmd_free(new);
          goto out;
       }
@@ -1412,7 +1420,7 @@
  */
 pte_t *pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
 {
-   if (pmd_none(*pmd)) {
+   if (!pmd_present(*pmd)) {
       pte_t *new;
 
       /* "fast" allocation can happen without dropping the lock.. */
@@ -1428,7 +1436,7 @@
           * Because we dropped the lock, we should re-check the
           * entry, as somebody else could have populated it..
           */
-         if (!pmd_none(*pmd)) {
+         if (pmd_present(*pmd)) {
             pte_free(new);
             goto out;
          }