Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
862
mm/rmap.c
Normal file
862
mm/rmap.c
Normal file
@@ -0,0 +1,862 @@
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/*
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* mm/rmap.c - physical to virtual reverse mappings
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*
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* Copyright 2001, Rik van Riel <riel@conectiva.com.br>
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* Released under the General Public License (GPL).
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*
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* Simple, low overhead reverse mapping scheme.
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* Please try to keep this thing as modular as possible.
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*
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* Provides methods for unmapping each kind of mapped page:
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* the anon methods track anonymous pages, and
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* the file methods track pages belonging to an inode.
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*
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* Original design by Rik van Riel <riel@conectiva.com.br> 2001
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* File methods by Dave McCracken <dmccr@us.ibm.com> 2003, 2004
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* Anonymous methods by Andrea Arcangeli <andrea@suse.de> 2004
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* Contributions by Hugh Dickins <hugh@veritas.com> 2003, 2004
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*/
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/*
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* Lock ordering in mm:
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*
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* inode->i_sem (while writing or truncating, not reading or faulting)
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* inode->i_alloc_sem
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*
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* When a page fault occurs in writing from user to file, down_read
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* of mmap_sem nests within i_sem; in sys_msync, i_sem nests within
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* down_read of mmap_sem; i_sem and down_write of mmap_sem are never
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* taken together; in truncation, i_sem is taken outermost.
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*
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* mm->mmap_sem
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* page->flags PG_locked (lock_page)
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* mapping->i_mmap_lock
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* anon_vma->lock
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* mm->page_table_lock
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* zone->lru_lock (in mark_page_accessed)
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* swap_list_lock (in swap_free etc's swap_info_get)
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* mmlist_lock (in mmput, drain_mmlist and others)
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* swap_device_lock (in swap_duplicate, swap_info_get)
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* mapping->private_lock (in __set_page_dirty_buffers)
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* inode_lock (in set_page_dirty's __mark_inode_dirty)
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* sb_lock (within inode_lock in fs/fs-writeback.c)
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* mapping->tree_lock (widely used, in set_page_dirty,
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* in arch-dependent flush_dcache_mmap_lock,
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* within inode_lock in __sync_single_inode)
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*/
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#include <linux/mm.h>
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#include <linux/pagemap.h>
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#include <linux/swap.h>
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#include <linux/swapops.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/rmap.h>
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#include <linux/rcupdate.h>
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#include <asm/tlbflush.h>
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//#define RMAP_DEBUG /* can be enabled only for debugging */
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kmem_cache_t *anon_vma_cachep;
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static inline void validate_anon_vma(struct vm_area_struct *find_vma)
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{
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#ifdef RMAP_DEBUG
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struct anon_vma *anon_vma = find_vma->anon_vma;
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struct vm_area_struct *vma;
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unsigned int mapcount = 0;
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int found = 0;
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list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
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mapcount++;
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BUG_ON(mapcount > 100000);
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if (vma == find_vma)
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found = 1;
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}
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BUG_ON(!found);
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#endif
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}
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/* This must be called under the mmap_sem. */
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int anon_vma_prepare(struct vm_area_struct *vma)
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{
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struct anon_vma *anon_vma = vma->anon_vma;
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might_sleep();
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if (unlikely(!anon_vma)) {
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struct mm_struct *mm = vma->vm_mm;
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struct anon_vma *allocated, *locked;
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anon_vma = find_mergeable_anon_vma(vma);
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if (anon_vma) {
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allocated = NULL;
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locked = anon_vma;
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spin_lock(&locked->lock);
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} else {
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anon_vma = anon_vma_alloc();
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if (unlikely(!anon_vma))
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return -ENOMEM;
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allocated = anon_vma;
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locked = NULL;
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}
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/* page_table_lock to protect against threads */
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spin_lock(&mm->page_table_lock);
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if (likely(!vma->anon_vma)) {
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vma->anon_vma = anon_vma;
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list_add(&vma->anon_vma_node, &anon_vma->head);
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allocated = NULL;
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}
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spin_unlock(&mm->page_table_lock);
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if (locked)
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spin_unlock(&locked->lock);
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if (unlikely(allocated))
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anon_vma_free(allocated);
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}
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return 0;
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}
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void __anon_vma_merge(struct vm_area_struct *vma, struct vm_area_struct *next)
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{
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BUG_ON(vma->anon_vma != next->anon_vma);
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list_del(&next->anon_vma_node);
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}
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void __anon_vma_link(struct vm_area_struct *vma)
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{
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struct anon_vma *anon_vma = vma->anon_vma;
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if (anon_vma) {
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list_add(&vma->anon_vma_node, &anon_vma->head);
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validate_anon_vma(vma);
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}
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}
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void anon_vma_link(struct vm_area_struct *vma)
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{
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struct anon_vma *anon_vma = vma->anon_vma;
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if (anon_vma) {
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spin_lock(&anon_vma->lock);
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list_add(&vma->anon_vma_node, &anon_vma->head);
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validate_anon_vma(vma);
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spin_unlock(&anon_vma->lock);
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}
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}
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void anon_vma_unlink(struct vm_area_struct *vma)
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{
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struct anon_vma *anon_vma = vma->anon_vma;
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int empty;
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if (!anon_vma)
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return;
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spin_lock(&anon_vma->lock);
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validate_anon_vma(vma);
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list_del(&vma->anon_vma_node);
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/* We must garbage collect the anon_vma if it's empty */
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empty = list_empty(&anon_vma->head);
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spin_unlock(&anon_vma->lock);
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if (empty)
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anon_vma_free(anon_vma);
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}
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static void anon_vma_ctor(void *data, kmem_cache_t *cachep, unsigned long flags)
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{
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if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
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SLAB_CTOR_CONSTRUCTOR) {
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struct anon_vma *anon_vma = data;
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spin_lock_init(&anon_vma->lock);
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INIT_LIST_HEAD(&anon_vma->head);
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}
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}
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void __init anon_vma_init(void)
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{
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anon_vma_cachep = kmem_cache_create("anon_vma", sizeof(struct anon_vma),
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0, SLAB_DESTROY_BY_RCU|SLAB_PANIC, anon_vma_ctor, NULL);
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}
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/*
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* Getting a lock on a stable anon_vma from a page off the LRU is
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* tricky: page_lock_anon_vma rely on RCU to guard against the races.
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*/
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static struct anon_vma *page_lock_anon_vma(struct page *page)
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{
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struct anon_vma *anon_vma = NULL;
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unsigned long anon_mapping;
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rcu_read_lock();
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anon_mapping = (unsigned long) page->mapping;
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if (!(anon_mapping & PAGE_MAPPING_ANON))
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goto out;
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if (!page_mapped(page))
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goto out;
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anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
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spin_lock(&anon_vma->lock);
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out:
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rcu_read_unlock();
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return anon_vma;
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}
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/*
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* At what user virtual address is page expected in vma?
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*/
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static inline unsigned long
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vma_address(struct page *page, struct vm_area_struct *vma)
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{
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pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
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unsigned long address;
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address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);
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if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {
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/* page should be within any vma from prio_tree_next */
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BUG_ON(!PageAnon(page));
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return -EFAULT;
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}
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return address;
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}
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/*
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* At what user virtual address is page expected in vma? checking that the
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* page matches the vma: currently only used by unuse_process, on anon pages.
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*/
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unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
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{
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if (PageAnon(page)) {
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if ((void *)vma->anon_vma !=
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(void *)page->mapping - PAGE_MAPPING_ANON)
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return -EFAULT;
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} else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
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if (vma->vm_file->f_mapping != page->mapping)
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return -EFAULT;
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} else
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return -EFAULT;
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return vma_address(page, vma);
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}
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/*
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* Subfunctions of page_referenced: page_referenced_one called
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* repeatedly from either page_referenced_anon or page_referenced_file.
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*/
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static int page_referenced_one(struct page *page,
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struct vm_area_struct *vma, unsigned int *mapcount, int ignore_token)
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{
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struct mm_struct *mm = vma->vm_mm;
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unsigned long address;
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pgd_t *pgd;
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pud_t *pud;
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pmd_t *pmd;
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pte_t *pte;
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int referenced = 0;
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if (!get_mm_counter(mm, rss))
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goto out;
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address = vma_address(page, vma);
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if (address == -EFAULT)
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goto out;
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spin_lock(&mm->page_table_lock);
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pgd = pgd_offset(mm, address);
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if (!pgd_present(*pgd))
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goto out_unlock;
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pud = pud_offset(pgd, address);
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if (!pud_present(*pud))
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goto out_unlock;
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pmd = pmd_offset(pud, address);
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if (!pmd_present(*pmd))
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goto out_unlock;
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pte = pte_offset_map(pmd, address);
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if (!pte_present(*pte))
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goto out_unmap;
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if (page_to_pfn(page) != pte_pfn(*pte))
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goto out_unmap;
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if (ptep_clear_flush_young(vma, address, pte))
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referenced++;
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if (mm != current->mm && !ignore_token && has_swap_token(mm))
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referenced++;
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(*mapcount)--;
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out_unmap:
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pte_unmap(pte);
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out_unlock:
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spin_unlock(&mm->page_table_lock);
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out:
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return referenced;
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}
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static int page_referenced_anon(struct page *page, int ignore_token)
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||||
{
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unsigned int mapcount;
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struct anon_vma *anon_vma;
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struct vm_area_struct *vma;
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int referenced = 0;
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||||
anon_vma = page_lock_anon_vma(page);
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if (!anon_vma)
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return referenced;
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mapcount = page_mapcount(page);
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list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
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referenced += page_referenced_one(page, vma, &mapcount,
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||||
ignore_token);
|
||||
if (!mapcount)
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||||
break;
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||||
}
|
||||
spin_unlock(&anon_vma->lock);
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||||
return referenced;
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||||
}
|
||||
|
||||
/**
|
||||
* page_referenced_file - referenced check for object-based rmap
|
||||
* @page: the page we're checking references on.
|
||||
*
|
||||
* For an object-based mapped page, find all the places it is mapped and
|
||||
* check/clear the referenced flag. This is done by following the page->mapping
|
||||
* pointer, then walking the chain of vmas it holds. It returns the number
|
||||
* of references it found.
|
||||
*
|
||||
* This function is only called from page_referenced for object-based pages.
|
||||
*/
|
||||
static int page_referenced_file(struct page *page, int ignore_token)
|
||||
{
|
||||
unsigned int mapcount;
|
||||
struct address_space *mapping = page->mapping;
|
||||
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
|
||||
struct vm_area_struct *vma;
|
||||
struct prio_tree_iter iter;
|
||||
int referenced = 0;
|
||||
|
||||
/*
|
||||
* The caller's checks on page->mapping and !PageAnon have made
|
||||
* sure that this is a file page: the check for page->mapping
|
||||
* excludes the case just before it gets set on an anon page.
|
||||
*/
|
||||
BUG_ON(PageAnon(page));
|
||||
|
||||
/*
|
||||
* The page lock not only makes sure that page->mapping cannot
|
||||
* suddenly be NULLified by truncation, it makes sure that the
|
||||
* structure at mapping cannot be freed and reused yet,
|
||||
* so we can safely take mapping->i_mmap_lock.
|
||||
*/
|
||||
BUG_ON(!PageLocked(page));
|
||||
|
||||
spin_lock(&mapping->i_mmap_lock);
|
||||
|
||||
/*
|
||||
* i_mmap_lock does not stabilize mapcount at all, but mapcount
|
||||
* is more likely to be accurate if we note it after spinning.
|
||||
*/
|
||||
mapcount = page_mapcount(page);
|
||||
|
||||
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
|
||||
if ((vma->vm_flags & (VM_LOCKED|VM_MAYSHARE))
|
||||
== (VM_LOCKED|VM_MAYSHARE)) {
|
||||
referenced++;
|
||||
break;
|
||||
}
|
||||
referenced += page_referenced_one(page, vma, &mapcount,
|
||||
ignore_token);
|
||||
if (!mapcount)
|
||||
break;
|
||||
}
|
||||
|
||||
spin_unlock(&mapping->i_mmap_lock);
|
||||
return referenced;
|
||||
}
|
||||
|
||||
/**
|
||||
* page_referenced - test if the page was referenced
|
||||
* @page: the page to test
|
||||
* @is_locked: caller holds lock on the page
|
||||
*
|
||||
* Quick test_and_clear_referenced for all mappings to a page,
|
||||
* returns the number of ptes which referenced the page.
|
||||
*/
|
||||
int page_referenced(struct page *page, int is_locked, int ignore_token)
|
||||
{
|
||||
int referenced = 0;
|
||||
|
||||
if (!swap_token_default_timeout)
|
||||
ignore_token = 1;
|
||||
|
||||
if (page_test_and_clear_young(page))
|
||||
referenced++;
|
||||
|
||||
if (TestClearPageReferenced(page))
|
||||
referenced++;
|
||||
|
||||
if (page_mapped(page) && page->mapping) {
|
||||
if (PageAnon(page))
|
||||
referenced += page_referenced_anon(page, ignore_token);
|
||||
else if (is_locked)
|
||||
referenced += page_referenced_file(page, ignore_token);
|
||||
else if (TestSetPageLocked(page))
|
||||
referenced++;
|
||||
else {
|
||||
if (page->mapping)
|
||||
referenced += page_referenced_file(page,
|
||||
ignore_token);
|
||||
unlock_page(page);
|
||||
}
|
||||
}
|
||||
return referenced;
|
||||
}
|
||||
|
||||
/**
|
||||
* page_add_anon_rmap - add pte mapping to an anonymous page
|
||||
* @page: the page to add the mapping to
|
||||
* @vma: the vm area in which the mapping is added
|
||||
* @address: the user virtual address mapped
|
||||
*
|
||||
* The caller needs to hold the mm->page_table_lock.
|
||||
*/
|
||||
void page_add_anon_rmap(struct page *page,
|
||||
struct vm_area_struct *vma, unsigned long address)
|
||||
{
|
||||
struct anon_vma *anon_vma = vma->anon_vma;
|
||||
pgoff_t index;
|
||||
|
||||
BUG_ON(PageReserved(page));
|
||||
BUG_ON(!anon_vma);
|
||||
|
||||
inc_mm_counter(vma->vm_mm, anon_rss);
|
||||
|
||||
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
||||
index = (address - vma->vm_start) >> PAGE_SHIFT;
|
||||
index += vma->vm_pgoff;
|
||||
index >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
|
||||
|
||||
if (atomic_inc_and_test(&page->_mapcount)) {
|
||||
page->index = index;
|
||||
page->mapping = (struct address_space *) anon_vma;
|
||||
inc_page_state(nr_mapped);
|
||||
}
|
||||
/* else checking page index and mapping is racy */
|
||||
}
|
||||
|
||||
/**
|
||||
* page_add_file_rmap - add pte mapping to a file page
|
||||
* @page: the page to add the mapping to
|
||||
*
|
||||
* The caller needs to hold the mm->page_table_lock.
|
||||
*/
|
||||
void page_add_file_rmap(struct page *page)
|
||||
{
|
||||
BUG_ON(PageAnon(page));
|
||||
if (!pfn_valid(page_to_pfn(page)) || PageReserved(page))
|
||||
return;
|
||||
|
||||
if (atomic_inc_and_test(&page->_mapcount))
|
||||
inc_page_state(nr_mapped);
|
||||
}
|
||||
|
||||
/**
|
||||
* page_remove_rmap - take down pte mapping from a page
|
||||
* @page: page to remove mapping from
|
||||
*
|
||||
* Caller needs to hold the mm->page_table_lock.
|
||||
*/
|
||||
void page_remove_rmap(struct page *page)
|
||||
{
|
||||
BUG_ON(PageReserved(page));
|
||||
|
||||
if (atomic_add_negative(-1, &page->_mapcount)) {
|
||||
BUG_ON(page_mapcount(page) < 0);
|
||||
/*
|
||||
* It would be tidy to reset the PageAnon mapping here,
|
||||
* but that might overwrite a racing page_add_anon_rmap
|
||||
* which increments mapcount after us but sets mapping
|
||||
* before us: so leave the reset to free_hot_cold_page,
|
||||
* and remember that it's only reliable while mapped.
|
||||
* Leaving it set also helps swapoff to reinstate ptes
|
||||
* faster for those pages still in swapcache.
|
||||
*/
|
||||
if (page_test_and_clear_dirty(page))
|
||||
set_page_dirty(page);
|
||||
dec_page_state(nr_mapped);
|
||||
}
|
||||
}
|
||||
|
||||
/*
|
||||
* Subfunctions of try_to_unmap: try_to_unmap_one called
|
||||
* repeatedly from either try_to_unmap_anon or try_to_unmap_file.
|
||||
*/
|
||||
static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma)
|
||||
{
|
||||
struct mm_struct *mm = vma->vm_mm;
|
||||
unsigned long address;
|
||||
pgd_t *pgd;
|
||||
pud_t *pud;
|
||||
pmd_t *pmd;
|
||||
pte_t *pte;
|
||||
pte_t pteval;
|
||||
int ret = SWAP_AGAIN;
|
||||
|
||||
if (!get_mm_counter(mm, rss))
|
||||
goto out;
|
||||
address = vma_address(page, vma);
|
||||
if (address == -EFAULT)
|
||||
goto out;
|
||||
|
||||
/*
|
||||
* We need the page_table_lock to protect us from page faults,
|
||||
* munmap, fork, etc...
|
||||
*/
|
||||
spin_lock(&mm->page_table_lock);
|
||||
|
||||
pgd = pgd_offset(mm, address);
|
||||
if (!pgd_present(*pgd))
|
||||
goto out_unlock;
|
||||
|
||||
pud = pud_offset(pgd, address);
|
||||
if (!pud_present(*pud))
|
||||
goto out_unlock;
|
||||
|
||||
pmd = pmd_offset(pud, address);
|
||||
if (!pmd_present(*pmd))
|
||||
goto out_unlock;
|
||||
|
||||
pte = pte_offset_map(pmd, address);
|
||||
if (!pte_present(*pte))
|
||||
goto out_unmap;
|
||||
|
||||
if (page_to_pfn(page) != pte_pfn(*pte))
|
||||
goto out_unmap;
|
||||
|
||||
/*
|
||||
* If the page is mlock()d, we cannot swap it out.
|
||||
* If it's recently referenced (perhaps page_referenced
|
||||
* skipped over this mm) then we should reactivate it.
|
||||
*/
|
||||
if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) ||
|
||||
ptep_clear_flush_young(vma, address, pte)) {
|
||||
ret = SWAP_FAIL;
|
||||
goto out_unmap;
|
||||
}
|
||||
|
||||
/*
|
||||
* Don't pull an anonymous page out from under get_user_pages.
|
||||
* GUP carefully breaks COW and raises page count (while holding
|
||||
* page_table_lock, as we have here) to make sure that the page
|
||||
* cannot be freed. If we unmap that page here, a user write
|
||||
* access to the virtual address will bring back the page, but
|
||||
* its raised count will (ironically) be taken to mean it's not
|
||||
* an exclusive swap page, do_wp_page will replace it by a copy
|
||||
* page, and the user never get to see the data GUP was holding
|
||||
* the original page for.
|
||||
*
|
||||
* This test is also useful for when swapoff (unuse_process) has
|
||||
* to drop page lock: its reference to the page stops existing
|
||||
* ptes from being unmapped, so swapoff can make progress.
|
||||
*/
|
||||
if (PageSwapCache(page) &&
|
||||
page_count(page) != page_mapcount(page) + 2) {
|
||||
ret = SWAP_FAIL;
|
||||
goto out_unmap;
|
||||
}
|
||||
|
||||
/* Nuke the page table entry. */
|
||||
flush_cache_page(vma, address, page_to_pfn(page));
|
||||
pteval = ptep_clear_flush(vma, address, pte);
|
||||
|
||||
/* Move the dirty bit to the physical page now the pte is gone. */
|
||||
if (pte_dirty(pteval))
|
||||
set_page_dirty(page);
|
||||
|
||||
if (PageAnon(page)) {
|
||||
swp_entry_t entry = { .val = page->private };
|
||||
/*
|
||||
* Store the swap location in the pte.
|
||||
* See handle_pte_fault() ...
|
||||
*/
|
||||
BUG_ON(!PageSwapCache(page));
|
||||
swap_duplicate(entry);
|
||||
if (list_empty(&mm->mmlist)) {
|
||||
spin_lock(&mmlist_lock);
|
||||
list_add(&mm->mmlist, &init_mm.mmlist);
|
||||
spin_unlock(&mmlist_lock);
|
||||
}
|
||||
set_pte_at(mm, address, pte, swp_entry_to_pte(entry));
|
||||
BUG_ON(pte_file(*pte));
|
||||
dec_mm_counter(mm, anon_rss);
|
||||
}
|
||||
|
||||
inc_mm_counter(mm, rss);
|
||||
page_remove_rmap(page);
|
||||
page_cache_release(page);
|
||||
|
||||
out_unmap:
|
||||
pte_unmap(pte);
|
||||
out_unlock:
|
||||
spin_unlock(&mm->page_table_lock);
|
||||
out:
|
||||
return ret;
|
||||
}
|
||||
|
||||
/*
|
||||
* objrmap doesn't work for nonlinear VMAs because the assumption that
|
||||
* offset-into-file correlates with offset-into-virtual-addresses does not hold.
|
||||
* Consequently, given a particular page and its ->index, we cannot locate the
|
||||
* ptes which are mapping that page without an exhaustive linear search.
|
||||
*
|
||||
* So what this code does is a mini "virtual scan" of each nonlinear VMA which
|
||||
* maps the file to which the target page belongs. The ->vm_private_data field
|
||||
* holds the current cursor into that scan. Successive searches will circulate
|
||||
* around the vma's virtual address space.
|
||||
*
|
||||
* So as more replacement pressure is applied to the pages in a nonlinear VMA,
|
||||
* more scanning pressure is placed against them as well. Eventually pages
|
||||
* will become fully unmapped and are eligible for eviction.
|
||||
*
|
||||
* For very sparsely populated VMAs this is a little inefficient - chances are
|
||||
* there there won't be many ptes located within the scan cluster. In this case
|
||||
* maybe we could scan further - to the end of the pte page, perhaps.
|
||||
*/
|
||||
#define CLUSTER_SIZE min(32*PAGE_SIZE, PMD_SIZE)
|
||||
#define CLUSTER_MASK (~(CLUSTER_SIZE - 1))
|
||||
|
||||
static void try_to_unmap_cluster(unsigned long cursor,
|
||||
unsigned int *mapcount, struct vm_area_struct *vma)
|
||||
{
|
||||
struct mm_struct *mm = vma->vm_mm;
|
||||
pgd_t *pgd;
|
||||
pud_t *pud;
|
||||
pmd_t *pmd;
|
||||
pte_t *pte;
|
||||
pte_t pteval;
|
||||
struct page *page;
|
||||
unsigned long address;
|
||||
unsigned long end;
|
||||
unsigned long pfn;
|
||||
|
||||
/*
|
||||
* We need the page_table_lock to protect us from page faults,
|
||||
* munmap, fork, etc...
|
||||
*/
|
||||
spin_lock(&mm->page_table_lock);
|
||||
|
||||
address = (vma->vm_start + cursor) & CLUSTER_MASK;
|
||||
end = address + CLUSTER_SIZE;
|
||||
if (address < vma->vm_start)
|
||||
address = vma->vm_start;
|
||||
if (end > vma->vm_end)
|
||||
end = vma->vm_end;
|
||||
|
||||
pgd = pgd_offset(mm, address);
|
||||
if (!pgd_present(*pgd))
|
||||
goto out_unlock;
|
||||
|
||||
pud = pud_offset(pgd, address);
|
||||
if (!pud_present(*pud))
|
||||
goto out_unlock;
|
||||
|
||||
pmd = pmd_offset(pud, address);
|
||||
if (!pmd_present(*pmd))
|
||||
goto out_unlock;
|
||||
|
||||
for (pte = pte_offset_map(pmd, address);
|
||||
address < end; pte++, address += PAGE_SIZE) {
|
||||
|
||||
if (!pte_present(*pte))
|
||||
continue;
|
||||
|
||||
pfn = pte_pfn(*pte);
|
||||
if (!pfn_valid(pfn))
|
||||
continue;
|
||||
|
||||
page = pfn_to_page(pfn);
|
||||
BUG_ON(PageAnon(page));
|
||||
if (PageReserved(page))
|
||||
continue;
|
||||
|
||||
if (ptep_clear_flush_young(vma, address, pte))
|
||||
continue;
|
||||
|
||||
/* Nuke the page table entry. */
|
||||
flush_cache_page(vma, address, pfn);
|
||||
pteval = ptep_clear_flush(vma, address, pte);
|
||||
|
||||
/* If nonlinear, store the file page offset in the pte. */
|
||||
if (page->index != linear_page_index(vma, address))
|
||||
set_pte_at(mm, address, pte, pgoff_to_pte(page->index));
|
||||
|
||||
/* Move the dirty bit to the physical page now the pte is gone. */
|
||||
if (pte_dirty(pteval))
|
||||
set_page_dirty(page);
|
||||
|
||||
page_remove_rmap(page);
|
||||
page_cache_release(page);
|
||||
dec_mm_counter(mm, rss);
|
||||
(*mapcount)--;
|
||||
}
|
||||
|
||||
pte_unmap(pte);
|
||||
|
||||
out_unlock:
|
||||
spin_unlock(&mm->page_table_lock);
|
||||
}
|
||||
|
||||
static int try_to_unmap_anon(struct page *page)
|
||||
{
|
||||
struct anon_vma *anon_vma;
|
||||
struct vm_area_struct *vma;
|
||||
int ret = SWAP_AGAIN;
|
||||
|
||||
anon_vma = page_lock_anon_vma(page);
|
||||
if (!anon_vma)
|
||||
return ret;
|
||||
|
||||
list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
|
||||
ret = try_to_unmap_one(page, vma);
|
||||
if (ret == SWAP_FAIL || !page_mapped(page))
|
||||
break;
|
||||
}
|
||||
spin_unlock(&anon_vma->lock);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/**
|
||||
* try_to_unmap_file - unmap file page using the object-based rmap method
|
||||
* @page: the page to unmap
|
||||
*
|
||||
* Find all the mappings of a page using the mapping pointer and the vma chains
|
||||
* contained in the address_space struct it points to.
|
||||
*
|
||||
* This function is only called from try_to_unmap for object-based pages.
|
||||
*/
|
||||
static int try_to_unmap_file(struct page *page)
|
||||
{
|
||||
struct address_space *mapping = page->mapping;
|
||||
pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
|
||||
struct vm_area_struct *vma;
|
||||
struct prio_tree_iter iter;
|
||||
int ret = SWAP_AGAIN;
|
||||
unsigned long cursor;
|
||||
unsigned long max_nl_cursor = 0;
|
||||
unsigned long max_nl_size = 0;
|
||||
unsigned int mapcount;
|
||||
|
||||
spin_lock(&mapping->i_mmap_lock);
|
||||
vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
|
||||
ret = try_to_unmap_one(page, vma);
|
||||
if (ret == SWAP_FAIL || !page_mapped(page))
|
||||
goto out;
|
||||
}
|
||||
|
||||
if (list_empty(&mapping->i_mmap_nonlinear))
|
||||
goto out;
|
||||
|
||||
list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
|
||||
shared.vm_set.list) {
|
||||
if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
|
||||
continue;
|
||||
cursor = (unsigned long) vma->vm_private_data;
|
||||
if (cursor > max_nl_cursor)
|
||||
max_nl_cursor = cursor;
|
||||
cursor = vma->vm_end - vma->vm_start;
|
||||
if (cursor > max_nl_size)
|
||||
max_nl_size = cursor;
|
||||
}
|
||||
|
||||
if (max_nl_size == 0) { /* any nonlinears locked or reserved */
|
||||
ret = SWAP_FAIL;
|
||||
goto out;
|
||||
}
|
||||
|
||||
/*
|
||||
* We don't try to search for this page in the nonlinear vmas,
|
||||
* and page_referenced wouldn't have found it anyway. Instead
|
||||
* just walk the nonlinear vmas trying to age and unmap some.
|
||||
* The mapcount of the page we came in with is irrelevant,
|
||||
* but even so use it as a guide to how hard we should try?
|
||||
*/
|
||||
mapcount = page_mapcount(page);
|
||||
if (!mapcount)
|
||||
goto out;
|
||||
cond_resched_lock(&mapping->i_mmap_lock);
|
||||
|
||||
max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
|
||||
if (max_nl_cursor == 0)
|
||||
max_nl_cursor = CLUSTER_SIZE;
|
||||
|
||||
do {
|
||||
list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
|
||||
shared.vm_set.list) {
|
||||
if (vma->vm_flags & (VM_LOCKED|VM_RESERVED))
|
||||
continue;
|
||||
cursor = (unsigned long) vma->vm_private_data;
|
||||
while (get_mm_counter(vma->vm_mm, rss) &&
|
||||
cursor < max_nl_cursor &&
|
||||
cursor < vma->vm_end - vma->vm_start) {
|
||||
try_to_unmap_cluster(cursor, &mapcount, vma);
|
||||
cursor += CLUSTER_SIZE;
|
||||
vma->vm_private_data = (void *) cursor;
|
||||
if ((int)mapcount <= 0)
|
||||
goto out;
|
||||
}
|
||||
vma->vm_private_data = (void *) max_nl_cursor;
|
||||
}
|
||||
cond_resched_lock(&mapping->i_mmap_lock);
|
||||
max_nl_cursor += CLUSTER_SIZE;
|
||||
} while (max_nl_cursor <= max_nl_size);
|
||||
|
||||
/*
|
||||
* Don't loop forever (perhaps all the remaining pages are
|
||||
* in locked vmas). Reset cursor on all unreserved nonlinear
|
||||
* vmas, now forgetting on which ones it had fallen behind.
|
||||
*/
|
||||
list_for_each_entry(vma, &mapping->i_mmap_nonlinear,
|
||||
shared.vm_set.list) {
|
||||
if (!(vma->vm_flags & VM_RESERVED))
|
||||
vma->vm_private_data = NULL;
|
||||
}
|
||||
out:
|
||||
spin_unlock(&mapping->i_mmap_lock);
|
||||
return ret;
|
||||
}
|
||||
|
||||
/**
|
||||
* try_to_unmap - try to remove all page table mappings to a page
|
||||
* @page: the page to get unmapped
|
||||
*
|
||||
* Tries to remove all the page table entries which are mapping this
|
||||
* page, used in the pageout path. Caller must hold the page lock.
|
||||
* Return values are:
|
||||
*
|
||||
* SWAP_SUCCESS - we succeeded in removing all mappings
|
||||
* SWAP_AGAIN - we missed a mapping, try again later
|
||||
* SWAP_FAIL - the page is unswappable
|
||||
*/
|
||||
int try_to_unmap(struct page *page)
|
||||
{
|
||||
int ret;
|
||||
|
||||
BUG_ON(PageReserved(page));
|
||||
BUG_ON(!PageLocked(page));
|
||||
|
||||
if (PageAnon(page))
|
||||
ret = try_to_unmap_anon(page);
|
||||
else
|
||||
ret = try_to_unmap_file(page);
|
||||
|
||||
if (!page_mapped(page))
|
||||
ret = SWAP_SUCCESS;
|
||||
return ret;
|
||||
}
|
||||
Reference in New Issue
Block a user