From 0f8053a509ceba4a077a50ea7b77039b5559b428 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 22 Mar 2006 00:08:33 -0800 Subject: [PATCH] mm: make __put_page internal Remove __put_page from outside the core mm/. It is dangerous because it does not handle compound pages nicely, and misses 1->0 transitions. If a user later appears that really needs the extra speed we can reevaluate. Signed-off-by: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index 17256bb2f4ef..e3042db2a2d6 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -8,6 +8,10 @@ * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ +#ifndef __MM_INTERNAL_H +#define __MM_INTERNAL_H + +#include static inline void set_page_refs(struct page *page, int order) { @@ -26,5 +30,12 @@ static inline void set_page_refs(struct page *page, int order) #endif /* CONFIG_MMU */ } +static inline void __put_page(struct page *page) +{ + atomic_dec(&page->_count); +} + extern void fastcall __init __free_pages_bootmem(struct page *page, unsigned int order); + +#endif -- cgit v1.2.3 From 84097518d1ecd2330f9488e4c2d09953a3340e74 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 22 Mar 2006 00:08:34 -0800 Subject: [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 Cc: David Howells (Needs testing, please). Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 12 ------------ 1 file changed, 12 deletions(-) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index e3042db2a2d6..7bb339779818 100644 --- 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) -- cgit v1.2.3 From 7835e98b2e3c66dba79cb0ff8ebb90a2fe030c29 Mon Sep 17 00:00:00 2001 From: Nick Piggin Date: Wed, 22 Mar 2006 00:08:40 -0800 Subject: [PATCH] remove set_page_count() outside mm/ set_page_count usage outside mm/ is limited to setting the refcount to 1. Remove set_page_count from outside mm/, and replace those users with init_page_count() and set_page_refcounted(). This allows more debug checking, and tighter control on how code is allowed to play around with page->_count. Signed-off-by: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/internal.h | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) (limited to 'mm/internal.h') diff --git a/mm/internal.h b/mm/internal.h index 7bb339779818..d20e3cc4aef0 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -13,8 +13,19 @@ #include -static inline void set_page_refs(struct page *page, int order) +static inline void set_page_count(struct page *page, int v) { + atomic_set(&page->_count, v); +} + +/* + * Turn a non-refcounted page (->_count == 0) into refcounted with + * a count of one. + */ +static inline void set_page_refcounted(struct page *page) +{ + BUG_ON(PageCompound(page) && page_private(page) != (unsigned long)page); + BUG_ON(atomic_read(&page->_count)); set_page_count(page, 1); } -- cgit v1.2.3