[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>

[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>
Nick Piggin · Linus Torvalds
1 parent 0f8053a509
Showing 6 changed files with 11 additions and 28 deletions Side-by-side Diff
fs/ramfs/file-nommu.c
include/linux/mm.h
mm/internal.h
mm/nommu.c
mm/page_alloc.c
mm/slab.c
@@ -87,8 +87,7 @@
 	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++)
@@ -327,11 +327,7 @@
  
 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
@@ -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)
@@ -159,7 +159,7 @@
 	/*
 	 * 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 @@
 	 * - 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;
  
@@ -422,11 +422,6 @@
 		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 @@
 		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 @@
 		set_page_count(page + i, 1);
 	}
 }
-#endif
  
 /*
  * Really, prep_compound_page() should be called from __rmqueue_bulk().  But
@@ -590,6 +590,8 @@
  
 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 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 @@
 	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);
...	...	@@ -87,8 +87,7 @@
87	87	xpages = 1UL << order;
88	88	npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
89	89
90		- for (loop = 0; loop < npages; loop++)
91		- set_page_count(pages + loop, 1);
	90	+ split_page(pages, order);
92	91
93	92	/* trim off any pages we don't actually require */
94	93	for (loop = npages; loop < xpages; loop++)
...	...	@@ -327,11 +327,7 @@
327	327
328	328	void put_page(struct page *page);
329	329
330		-#ifdef CONFIG_MMU
331	330	void split_page(struct page *page, unsigned int order);
332		-#else
333		-static inline void split_page(struct page *page, unsigned int order) {}
334		-#endif
335	331
336	332	/*
337	333	* Multiple processes may "see" the same page. E.g. for untouched
...	...	@@ -15,19 +15,7 @@
15	15
16	16	static inline void set_page_refs(struct page *page, int order)
17	17	{
18		-#ifdef CONFIG_MMU
19	18	set_page_count(page, 1);
20		-#else
21		- int i;
22		-
23		- /*
24		- * We need to reference all the pages for this order, otherwise if
25		- * anyone accesses one of the pages with (get/put) it will be freed.
26		- * - eg: access_process_vm()
27		- */
28		- for (i = 0; i < (1 << order); i++)
29		- set_page_count(page + i, 1);
30		-#endif /* CONFIG_MMU */
31	19	}
32	20
33	21	static inline void __put_page(struct page *page)
...	...	@@ -159,7 +159,7 @@
159	159	/*
160	160	* kmalloc doesn't like __GFP_HIGHMEM for some reason
161	161	*/
162		- return kmalloc(size, gfp_mask & ~__GFP_HIGHMEM);
	162	+ return kmalloc(size, (gfp_mask \| __GFP_COMP) & ~__GFP_HIGHMEM);
163	163	}
164	164
165	165	struct page * vmalloc_to_page(void *addr)
...	...	@@ -623,7 +623,7 @@
623	623	* - note that this may not return a page-aligned address if the object
624	624	* we're allocating is smaller than a page
625	625	*/
626		- base = kmalloc(len, GFP_KERNEL);
	626	+ base = kmalloc(len, GFP_KERNEL\|__GFP_COMP);
627	627	if (!base)
628	628	goto enomem;
629	629
...	...	@@ -422,11 +422,6 @@
422	422	mutex_debug_check_no_locks_freed(page_address(page),
423	423	PAGE_SIZE<<order);
424	424
425		-#ifndef CONFIG_MMU
426		- for (i = 1 ; i < (1 << order) ; ++i)
427		- __put_page(page + i);
428		-#endif
429		-
430	425	for (i = 0 ; i < (1 << order) ; ++i)
431	426	reserved += free_pages_check(page + i);
432	427	if (reserved)
...	...	@@ -746,7 +741,6 @@
746	741	clear_highpage(page + i);
747	742	}
748	743
749		-#ifdef CONFIG_MMU
750	744	/*
751	745	* split_page takes a non-compound higher-order page, and splits it into
752	746	* n (1<<order) sub-pages: page[0..n]
...	...	@@ -766,7 +760,6 @@
766	760	set_page_count(page + i, 1);
767	761	}
768	762	}
769		-#endif
770	763
771	764	/*
772	765	* Really, prep_compound_page() should be called from __rmqueue_bulk(). But
...	...	@@ -590,6 +590,8 @@
590	590
591	591	static inline struct kmem_cache page_get_cache(struct page page)
592	592	{
	593	+ if (unlikely(PageCompound(page)))
	594	+ page = (struct page *)page_private(page);
593	595	return (struct kmem_cache *)page->lru.next;
594	596	}
595	597
...	...	@@ -600,6 +602,8 @@
600	602
601	603	static inline struct slab page_get_slab(struct page page)
602	604	{
	605	+ if (unlikely(PageCompound(page)))
	606	+ page = (struct page *)page_private(page);
603	607	return (struct slab *)page->lru.prev;
604	608	}
605	609
606	610
...	...	@@ -2412,8 +2416,11 @@
2412	2416	struct page *page;
2413	2417
2414	2418	/* Nasty!!!!!! I hope this is OK. */
2415		- i = 1 << cachep->gfporder;
2416	2419	page = virt_to_page(objp);
	2420	+
	2421	+ i = 1;
	2422	+ if (likely(!PageCompound(page)))
	2423	+ i <<= cachep->gfporder;
2417	2424	do {
2418	2425	page_set_cache(page, cachep);
2419	2426	page_set_slab(page, slabp);