2005-04-16 22:20:36 +00:00
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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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[PATCH] swap: swap_lock replace list+device
The idea of a swap_device_lock per device, and a swap_list_lock over them all,
is appealing; but in practice almost every holder of swap_device_lock must
already hold swap_list_lock, which defeats the purpose of the split.
The only exceptions have been swap_duplicate, valid_swaphandles and an
untrodden path in try_to_unuse (plus a few places added in this series).
valid_swaphandles doesn't show up high in profiles, but swap_duplicate does
demand attention. However, with the hold time in get_swap_pages so much
reduced, I've not yet found a load and set of swap device priorities to show
even swap_duplicate benefitting from the split. Certainly the split is mere
overhead in the common case of a single swap device.
So, replace swap_list_lock and swap_device_lock by spinlock_t swap_lock
(generally we seem to prefer an _ in the name, and not hide in a macro).
If someone can show a regression in swap_duplicate, then probably we should
add a hashlock for the swap_map entries alone (shorts being anatomic), so as
to help the case of the single swap device too.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-03 22:54:41 +00:00
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* swap_lock (in swap_duplicate, swap_info_get)
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2005-04-16 22:20:36 +00:00
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* mmlist_lock (in mmput, drain_mmlist and others)
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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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|
2005-05-01 15:58:36 +00:00
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/*
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* Check that @page is mapped at @address into @mm.
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*
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* On success returns with mapped pte and locked mm->page_table_lock.
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*/
|
2005-06-24 05:05:25 +00:00
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pte_t *page_check_address(struct page *page, struct mm_struct *mm,
|
2005-10-30 01:16:31 +00:00
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unsigned long address, spinlock_t **ptlp)
|
2005-05-01 15:58:36 +00:00
|
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{
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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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|
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pte_t *pte;
|
2005-10-30 01:16:31 +00:00
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spinlock_t *ptl;
|
2005-05-01 15:58:36 +00:00
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pgd = pgd_offset(mm, address);
|
2005-10-30 01:16:31 +00:00
|
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if (!pgd_present(*pgd))
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return NULL;
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|
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pud = pud_offset(pgd, address);
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|
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if (!pud_present(*pud))
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return NULL;
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|
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|
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pmd = pmd_offset(pud, address);
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|
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if (!pmd_present(*pmd))
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return NULL;
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|
|
|
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|
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pte = pte_offset_map(pmd, address);
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|
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/* Make a quick check before getting the lock */
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|
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if (!pte_present(*pte)) {
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|
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pte_unmap(pte);
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return NULL;
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}
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|
|
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ptl = &mm->page_table_lock;
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|
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spin_lock(ptl);
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|
|
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if (pte_present(*pte) && page_to_pfn(page) == pte_pfn(*pte)) {
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|
|
*ptlp = ptl;
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return pte;
|
2005-05-01 15:58:36 +00:00
|
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|
}
|
2005-10-30 01:16:31 +00:00
|
|
|
pte_unmap_unlock(pte, ptl);
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|
|
return NULL;
|
2005-05-01 15:58:36 +00:00
|
|
|
}
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
/*
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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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|
|
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struct vm_area_struct *vma, unsigned int *mapcount, int ignore_token)
|
|
|
|
{
|
|
|
|
struct mm_struct *mm = vma->vm_mm;
|
|
|
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unsigned long address;
|
|
|
|
pte_t *pte;
|
2005-10-30 01:16:31 +00:00
|
|
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spinlock_t *ptl;
|
2005-04-16 22:20:36 +00:00
|
|
|
int referenced = 0;
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|
|
|
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|
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address = vma_address(page, vma);
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|
|
if (address == -EFAULT)
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|
|
goto out;
|
|
|
|
|
2005-10-30 01:16:31 +00:00
|
|
|
pte = page_check_address(page, mm, address, &ptl);
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|
|
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if (!pte)
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goto out;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
2005-10-30 01:16:31 +00:00
|
|
|
if (ptep_clear_flush_young(vma, address, pte))
|
|
|
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referenced++;
|
2005-04-16 22:20:36 +00:00
|
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|
2005-10-30 01:16:31 +00:00
|
|
|
/* Pretend the page is referenced if the task has the
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|
|
|
swap token and is in the middle of a page fault. */
|
|
|
|
if (mm != current->mm && !ignore_token && has_swap_token(mm) &&
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|
|
|
rwsem_is_locked(&mm->mmap_sem))
|
|
|
|
referenced++;
|
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|
|
|
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|
|
(*mapcount)--;
|
|
|
|
pte_unmap_unlock(pte, ptl);
|
2005-04-16 22:20:36 +00:00
|
|
|
out:
|
|
|
|
return referenced;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int page_referenced_anon(struct page *page, int ignore_token)
|
|
|
|
{
|
|
|
|
unsigned int mapcount;
|
|
|
|
struct anon_vma *anon_vma;
|
|
|
|
struct vm_area_struct *vma;
|
|
|
|
int referenced = 0;
|
|
|
|
|
|
|
|
anon_vma = page_lock_anon_vma(page);
|
|
|
|
if (!anon_vma)
|
|
|
|
return referenced;
|
|
|
|
|
|
|
|
mapcount = page_mapcount(page);
|
|
|
|
list_for_each_entry(vma, &anon_vma->head, anon_vma_node) {
|
|
|
|
referenced += page_referenced_one(page, vma, &mapcount,
|
|
|
|
ignore_token);
|
|
|
|
if (!mapcount)
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
spin_unlock(&anon_vma->lock);
|
|
|
|
return referenced;
|
|
|
|
}
|
|
|
|
|
|
|
|
/**
|
|
|
|
* 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)
|
|
|
|
{
|
|
|
|
if (atomic_inc_and_test(&page->_mapcount)) {
|
2005-09-03 22:54:47 +00:00
|
|
|
struct anon_vma *anon_vma = vma->anon_vma;
|
|
|
|
|
|
|
|
BUG_ON(!anon_vma);
|
|
|
|
anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
|
2005-04-16 22:20:36 +00:00
|
|
|
page->mapping = (struct address_space *) anon_vma;
|
2005-09-03 22:54:47 +00:00
|
|
|
|
2005-09-03 22:54:48 +00:00
|
|
|
page->index = linear_page_index(vma, address);
|
2005-09-03 22:54:47 +00:00
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
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));
|
2005-10-30 01:16:12 +00:00
|
|
|
BUG_ON(!pfn_valid(page_to_pfn(page)));
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
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)
|
|
|
|
{
|
|
|
|
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;
|
|
|
|
pte_t *pte;
|
|
|
|
pte_t pteval;
|
2005-10-30 01:16:31 +00:00
|
|
|
spinlock_t *ptl;
|
2005-04-16 22:20:36 +00:00
|
|
|
int ret = SWAP_AGAIN;
|
|
|
|
|
|
|
|
address = vma_address(page, vma);
|
|
|
|
if (address == -EFAULT)
|
|
|
|
goto out;
|
|
|
|
|
2005-10-30 01:16:31 +00:00
|
|
|
pte = page_check_address(page, mm, address, &ptl);
|
|
|
|
if (!pte)
|
2005-05-01 15:58:36 +00:00
|
|
|
goto out;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
/*
|
|
|
|
* 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.
|
2005-09-03 22:54:46 +00:00
|
|
|
*
|
|
|
|
* Pages belonging to VM_RESERVED regions should not happen here.
|
2005-04-16 22:20:36 +00:00
|
|
|
*/
|
|
|
|
if ((vma->vm_flags & (VM_LOCKED|VM_RESERVED)) ||
|
|
|
|
ptep_clear_flush_young(vma, address, pte)) {
|
|
|
|
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);
|
|
|
|
|
[PATCH] mm: update_hiwaters just in time
update_mem_hiwater has attracted various criticisms, in particular from those
concerned with mm scalability. Originally it was called whenever rss or
total_vm got raised. Then many of those callsites were replaced by a timer
tick call from account_system_time. Now Frank van Maarseveen reports that to
be found inadequate. How about this? Works for Frank.
Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros
update_hiwater_rss and update_hiwater_vm. Don't attempt to keep
mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually
by 1): those are hot paths. Do the opposite, update only when about to lower
rss (usually by many), or just before final accounting in do_exit. Handle
mm->hiwater_vm in the same way, though it's much less of an issue. Demand
that whoever collects these hiwater statistics do the work of taking the
maximum with rss or total_vm.
And there has been no collector of these hiwater statistics in the tree. The
new convention needs an example, so match Frank's usage by adding a VmPeak
line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS
(High-Water-Mark or High-Water-Memory).
There was a particular anomaly during mremap move, that hiwater_vm might be
captured too high. A fleeting such anomaly remains, but it's quickly
corrected now, whereas before it would stick.
What locking? None: if the app is racy then these statistics will be racy,
it's not worth any overhead to make them exact. But whenever it suits,
hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under
page_table_lock (for now) or with preemption disabled (later on): without
going to any trouble, minimize the time between reading current values and
updating, to minimize those occasions when a racing thread bumps a count up
and back down in between.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 01:16:18 +00:00
|
|
|
/* Update high watermark before we lower rss */
|
|
|
|
update_hiwater_rss(mm);
|
|
|
|
|
2005-04-16 22:20:36 +00:00
|
|
|
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);
|
2005-10-30 01:16:05 +00:00
|
|
|
} else
|
|
|
|
dec_mm_counter(mm, file_rss);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
page_remove_rmap(page);
|
|
|
|
page_cache_release(page);
|
|
|
|
|
|
|
|
out_unmap:
|
2005-10-30 01:16:31 +00:00
|
|
|
pte_unmap_unlock(pte, ptl);
|
2005-04-16 22:20:36 +00:00
|
|
|
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;
|
2005-10-30 01:16:31 +00:00
|
|
|
pte_t *pte;
|
2005-04-16 22:20:36 +00:00
|
|
|
pte_t pteval;
|
2005-10-30 01:16:31 +00:00
|
|
|
spinlock_t *ptl;
|
2005-04-16 22:20:36 +00:00
|
|
|
struct page *page;
|
|
|
|
unsigned long address;
|
|
|
|
unsigned long end;
|
|
|
|
unsigned long pfn;
|
|
|
|
|
|
|
|
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))
|
2005-10-30 01:16:31 +00:00
|
|
|
return;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
pud = pud_offset(pgd, address);
|
|
|
|
if (!pud_present(*pud))
|
2005-10-30 01:16:31 +00:00
|
|
|
return;
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
pmd = pmd_offset(pud, address);
|
|
|
|
if (!pmd_present(*pmd))
|
2005-10-30 01:16:31 +00:00
|
|
|
return;
|
|
|
|
|
|
|
|
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
|
2005-04-16 22:20:36 +00:00
|
|
|
|
[PATCH] mm: update_hiwaters just in time
update_mem_hiwater has attracted various criticisms, in particular from those
concerned with mm scalability. Originally it was called whenever rss or
total_vm got raised. Then many of those callsites were replaced by a timer
tick call from account_system_time. Now Frank van Maarseveen reports that to
be found inadequate. How about this? Works for Frank.
Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros
update_hiwater_rss and update_hiwater_vm. Don't attempt to keep
mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually
by 1): those are hot paths. Do the opposite, update only when about to lower
rss (usually by many), or just before final accounting in do_exit. Handle
mm->hiwater_vm in the same way, though it's much less of an issue. Demand
that whoever collects these hiwater statistics do the work of taking the
maximum with rss or total_vm.
And there has been no collector of these hiwater statistics in the tree. The
new convention needs an example, so match Frank's usage by adding a VmPeak
line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS
(High-Water-Mark or High-Water-Memory).
There was a particular anomaly during mremap move, that hiwater_vm might be
captured too high. A fleeting such anomaly remains, but it's quickly
corrected now, whereas before it would stick.
What locking? None: if the app is racy then these statistics will be racy,
it's not worth any overhead to make them exact. But whenever it suits,
hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under
page_table_lock (for now) or with preemption disabled (later on): without
going to any trouble, minimize the time between reading current values and
updating, to minimize those occasions when a racing thread bumps a count up
and back down in between.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 01:16:18 +00:00
|
|
|
/* Update high watermark before we lower rss */
|
|
|
|
update_hiwater_rss(mm);
|
|
|
|
|
2005-10-30 01:16:31 +00:00
|
|
|
for (; address < end; pte++, address += PAGE_SIZE) {
|
2005-04-16 22:20:36 +00:00
|
|
|
if (!pte_present(*pte))
|
|
|
|
continue;
|
|
|
|
|
|
|
|
pfn = pte_pfn(*pte);
|
2005-10-30 01:16:12 +00:00
|
|
|
if (unlikely(!pfn_valid(pfn))) {
|
|
|
|
print_bad_pte(vma, *pte, address);
|
2005-04-16 22:20:36 +00:00
|
|
|
continue;
|
2005-10-30 01:16:12 +00:00
|
|
|
}
|
2005-04-16 22:20:36 +00:00
|
|
|
|
|
|
|
page = pfn_to_page(pfn);
|
|
|
|
BUG_ON(PageAnon(page));
|
|
|
|
|
|
|
|
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);
|
2005-10-30 01:16:05 +00:00
|
|
|
dec_mm_counter(mm, file_rss);
|
2005-04-16 22:20:36 +00:00
|
|
|
(*mapcount)--;
|
|
|
|
}
|
2005-10-30 01:16:31 +00:00
|
|
|
pte_unmap_unlock(pte - 1, ptl);
|
2005-04-16 22:20:36 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
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;
|
2005-09-03 22:54:43 +00:00
|
|
|
while ( cursor < max_nl_cursor &&
|
2005-04-16 22:20:36 +00:00
|
|
|
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(!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;
|
|
|
|
}
|
2005-05-01 15:58:36 +00:00
|
|
|
|