[PATCH] mm: nommu use compound pages

Now that compound page handling is properly fixed in the VM, move nommu
over to using compound pages rather than rolling their own refcounting.

nommu vm page refcounting is broken anyway, but there is no need to have
divergent code in the core VM now, nor when it gets fixed.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: David Howells <dhowells@redhat.com>
(Needs testing, please).
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/fs/ramfs/file-nommu.c b/fs/ramfs/file-nommu.c
index 3f810acd0bfadaaf621db94d3d5496f44f6de43f..b1ca234068f67173816c51c49bceecfe2c66bed9 100644 (file)
--- a/fs/ramfs/file-nommu.c
+++ b/fs/ramfs/file-nommu.c
@@ -87,8 +87,7 @@ static int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
        xpages = 1UL << order;
        npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
 
-       for (loop = 0; loop < npages; loop++)
-               set_page_count(pages + loop, 1);
+       split_page(pages, order);
 
        /* trim off any pages we don't actually require */
        for (loop = npages; loop < xpages; loop++)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 9b3cdfc8046d974258c3b092d8f953bf1ce79e16..3d84b7a35e0dcc6692b6e5bcfd4cc334c11ed604 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -327,11 +327,7 @@ static inline void get_page(struct page *page)
 
 void put_page(struct page *page);
 
-#ifdef CONFIG_MMU
 void split_page(struct page *page, unsigned int order);
-#else
-static inline void split_page(struct page *page, unsigned int order) {}
-#endif
 
 /*
  * Multiple processes may "see" the same page. E.g. for untouched

diff --git a/mm/internal.h b/mm/internal.h
index e3042db2a2d651c61d2d4d0e3cae2e3fdd8ca9ed..7bb3397798188af758947b19f0dc6dd945bf30d2 100644 (file)
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -15,19 +15,7 @@
 
 static inline void set_page_refs(struct page *page, int order)
 {
-#ifdef CONFIG_MMU
        set_page_count(page, 1);
-#else
-       int i;
-
-       /*
-        * We need to reference all the pages for this order, otherwise if
-        * anyone accesses one of the pages with (get/put) it will be freed.
-        * - eg: access_process_vm()
-        */
-       for (i = 0; i < (1 << order); i++)
-               set_page_count(page + i, 1);
-#endif /* CONFIG_MMU */
 }
 
 static inline void __put_page(struct page *page)

diff --git a/mm/nommu.c b/mm/nommu.c
index 4951f4786f2815b05b25eb13d4a09c7289cbff95..db45efac17cc218e390dd4a8b6d8366219c546a3 100644 (file)
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -159,7 +159,7 @@ void *__vmalloc(unsigned long size, gfp_t gfp_mask, pgprot_t prot)
        /*
         * kmalloc doesn't like __GFP_HIGHMEM for some reason
         */
-       return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM);
+       return kmalloc(size, (gfp_mask | __GFP_COMP) & ~__GFP_HIGHMEM);
 }
 
 struct page * vmalloc_to_page(void *addr)
@@ -623,7 +623,7 @@ static int do_mmap_private(struct vm_area_struct *vma, unsigned long len)
         * - note that this may not return a page-aligned address if the object
         *   we're allocating is smaller than a page
         */
-       base = kmalloc(len, GFP_KERNEL);
+       base = kmalloc(len, GFP_KERNEL|__GFP_COMP);
        if (!base)
                goto enomem;
 

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 7aa0181287e1c0644166d7a9a2973b89a40dcadb..e197818a7cf660d30e9e7e934871047db7c456c2 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -422,11 +422,6 @@ static void __free_pages_ok(struct page *page, unsigned int order)
                mutex_debug_check_no_locks_freed(page_address(page),
                                                 PAGE_SIZE<<order);
 
-#ifndef CONFIG_MMU
-       for (i = 1 ; i < (1 << order) ; ++i)
-               __put_page(page + i);
-#endif
-
        for (i = 0 ; i < (1 << order) ; ++i)
                reserved += free_pages_check(page + i);
        if (reserved)
@@ -746,7 +741,6 @@ static inline void prep_zero_page(struct page *page, int order, gfp_t gfp_flags)
                clear_highpage(page + i);
 }
 
-#ifdef CONFIG_MMU
 /*
  * split_page takes a non-compound higher-order page, and splits it into
  * n (1<<order) sub-pages: page[0..n]
@@ -766,7 +760,6 @@ void split_page(struct page *page, unsigned int order)
                set_page_count(page + i, 1);
        }
 }
-#endif
 
 /*
  * Really, prep_compound_page() should be called from __rmqueue_bulk().  But

diff --git a/mm/slab.c b/mm/slab.c
index f477acfb732f00efbd48a062df55da33c84ed41c..ff0ab772f49d13d5fa27374d53bf902540ec8e3b 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -590,6 +590,8 @@ static inline void page_set_cache(struct page *page, struct kmem_cache *cache)
 
 static inline struct kmem_cache *page_get_cache(struct page *page)
 {
+       if (unlikely(PageCompound(page)))
+               page = (struct page *)page_private(page);
        return (struct kmem_cache *)page->lru.next;
 }
 
@@ -600,6 +602,8 @@ static inline void page_set_slab(struct page *page, struct slab *slab)
 
 static inline struct slab *page_get_slab(struct page *page)
 {
+       if (unlikely(PageCompound(page)))
+               page = (struct page *)page_private(page);
        return (struct slab *)page->lru.prev;
 }
 
@@ -2412,8 +2416,11 @@ static void set_slab_attr(struct kmem_cache *cachep, struct slab *slabp,
        struct page *page;
 
        /* Nasty!!!!!! I hope this is OK. */
-       i = 1 << cachep->gfporder;
        page = virt_to_page(objp);
+
+       i = 1;
+       if (likely(!PageCompound(page)))
+               i <<= cachep->gfporder;
        do {
                page_set_cache(page, cachep);
                page_set_slab(page, slabp);