diff options
Diffstat (limited to 'include/linux/rmap.h')
| -rw-r--r-- | include/linux/rmap.h | 63 |
1 files changed, 62 insertions, 1 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 620987fa9607..e3148341f476 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -2,18 +2,75 @@ #define _LINUX_RMAP_H /* * Declarations for Reverse Mapping functions in mm/rmap.c - * Its structures are declared within that file. */ #include <linux/config.h> +#include <linux/list.h> +#include <linux/slab.h> +#include <linux/spinlock.h> #define page_map_lock(page) \ bit_spin_lock(PG_maplock, (unsigned long *)&(page)->flags) #define page_map_unlock(page) \ bit_spin_unlock(PG_maplock, (unsigned long *)&(page)->flags) +/* + * The anon_vma heads a list of private "related" vmas, to scan if + * an anonymous page pointing to this anon_vma needs to be unmapped: + * the vmas on the list will be related by forking, or by splitting. + * + * Since vmas come and go as they are split and merged (particularly + * in mprotect), the mapping field of an anonymous page cannot point + * directly to a vma: instead it points to an anon_vma, on whose list + * the related vmas can be easily linked or unlinked. + * + * After unlinking the last vma on the list, we must garbage collect + * the anon_vma object itself: we're guaranteed no page can be + * pointing to this anon_vma once its vma list is empty. + */ +struct anon_vma { + spinlock_t lock; /* Serialize access to vma list */ + struct list_head head; /* List of private "related" vmas */ +}; + #ifdef CONFIG_MMU +extern kmem_cache_t *anon_vma_cachep; + +static inline struct anon_vma *anon_vma_alloc(void) +{ + return kmem_cache_alloc(anon_vma_cachep, SLAB_KERNEL); +} + +static inline void anon_vma_free(struct anon_vma *anon_vma) +{ + kmem_cache_free(anon_vma_cachep, anon_vma); +} + +static inline void anon_vma_lock(struct vm_area_struct *vma) +{ + struct anon_vma *anon_vma = vma->anon_vma; + if (anon_vma) + spin_lock(&anon_vma->lock); +} + +static inline void anon_vma_unlock(struct vm_area_struct *vma) +{ + struct anon_vma *anon_vma = vma->anon_vma; + if (anon_vma) + spin_unlock(&anon_vma->lock); +} + +/* + * anon_vma helper functions. + */ +void anon_vma_init(void); /* create anon_vma_cachep */ +int anon_vma_prepare(struct vm_area_struct *); +void __anon_vma_merge(struct vm_area_struct *, struct vm_area_struct *); +void anon_vma_unlink(struct vm_area_struct *); +void anon_vma_link(struct vm_area_struct *); +void __anon_vma_link(struct vm_area_struct *); + /* * rmap interfaces called when adding or removing pte of page */ @@ -43,6 +100,10 @@ int try_to_unmap(struct page *); #else /* !CONFIG_MMU */ +#define anon_vma_init() do {} while (0) +#define anon_vma_prepare(vma) (0) +#define anon_vma_link(vma) do {} while (0) + #define page_referenced(page) TestClearPageReferenced(page) #define try_to_unmap(page) SWAP_FAIL |