static int unuse_mm(struct mm_struct *mm,
swp_entry_t entry, struct page *page)
{
struct vm_area_struct *vma;
if (!down_read_trylock(&mm->mmap_sem)) {
/*
* Activate page so shrink_cache is unlikely to unmap its
* ptes while lock is dropped, so swapoff can make progress.
*/
activate_page(page);
unlock_page(page);
down_read(&mm->mmap_sem);
lock_page(page);
}
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->anon_vma && unuse_vma(vma, entry, page))
break;
}
up_read(&mm->mmap_sem);
/*
* Currently unuse_mm cannot fail, but leave error handling
* at call sites for now, since we change it from time to time.
*/
return 0;
}
/*
* Mark a page as having seen activity.
*
* inactive,unreferenced -> inactive,referenced
* inactive,referenced -> active,unreferenced
* active,unreferenced -> active,referenced
*
* When a newly allocated page is not yet visible, so safe for non-atomic ops,
* __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
*/
void mark_page_accessed(struct page *page)
{
page = compound_head(page);
if (!PageActive(page) && !PageUnevictable(page) &&
PageReferenced(page)) {
/*
* If the page is on the LRU, queue it for activation via
* activate_page_pvecs. Otherwise, assume the page is on a
* pagevec, mark it active and it'll be moved to the active
* LRU on the next drain.
*/
if (PageLRU(page))
activate_page(page);
else
__lru_cache_activate_page(page);
ClearPageReferenced(page);
if (page_is_file_cache(page))
workingset_activation(page);
} else if (!PageReferenced(page)) {
SetPageReferenced(page);
}
if (page_is_idle(page))
clear_page_idle(page);
}
/*
* No need to decide whether this PTE shares the swap entry with others,
* just let do_wp_page work it out if a write is requested later - to
* force COW, vm_page_prot omits write permission from any private vma.
*/
static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, swp_entry_t entry, struct page *page)
{
spinlock_t *ptl;
pte_t *pte;
int ret = 1;
if (mem_cgroup_charge(page, vma->vm_mm, GFP_KERNEL))
ret = -ENOMEM;
pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
if (unlikely(!pte_same(*pte, swp_entry_to_pte(entry)))) {
if (ret > 0)
mem_cgroup_uncharge_page(page);
ret = 0;
goto out;
}
inc_mm_counter(vma->vm_mm, anon_rss);
get_page(page);
set_pte_at(vma->vm_mm, addr, pte,
pte_mkold(mk_pte(page, vma->vm_page_prot)));
page_add_anon_rmap(page, vma, addr);
swap_free(entry);
/*
* Move the page to the active list so it is not
* immediately swapped out again after swapon.
*/
activate_page(page);
out:
pte_unmap_unlock(pte, ptl);
return ret;
}
/*
* Mark a page as having seen activity.
*
* inactive,unreferenced -> inactive,referenced
* inactive,referenced -> active,unreferenced
* active,unreferenced -> active,referenced
*/
void fastcall mark_page_accessed(struct page *page)
{
if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
activate_page(page);
ClearPageReferenced(page);
} else if (!PageReferenced(page)) {
SetPageReferenced(page);
}
}
/*
* Mark a page as having seen activity.
*
* inactive,unreferenced -> inactive,referenced
* inactive,referenced -> active,unreferenced
* active,unreferenced -> active,referenced
*/
void mark_page_accessed(struct page *page)
{
if (!PageActive(page) && !PageUnevictable(page) &&
PageReferenced(page) && PageLRU(page)) {
activate_page(page);
ClearPageReferenced(page);
} else if (!PageReferenced(page)) {
SetPageReferenced(page);
}
}
/*
* mark_page_accessed：页访问的状态变化
* 非活动页的第一次访问状态变化: inactive,unreferenced -> inactive,referenced
* 非活动页的第二次访问状态变化: inactive,referenced -> active,unreferenced
* 活动页的第一次访问状态变化: active,unreferenced -> active,referenced
*/
void mark_page_accessed(struct page *page)
{
if (!PageActive(page) && !PageUnevictable(page) &&
PageReferenced(page) && PageLRU(page)) {
/* 非活动页的第二次访问:
* 将会使页从非活动链表移动到
* 活动链表,并且设置unreference*/
activate_page(page);
ClearPageReferenced(page);
} else if (!PageReferenced(page)) {
/*第一次访问非活动page或者访问活动页时只设置PG_reference*/
SetPageReferenced(page);
}
}
/*
* No need to decide whether this PTE shares the swap entry with others,
* just let do_wp_page work it out if a write is requested later - to
* force COW, vm_page_prot omits write permission from any private vma.
*/
static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
unsigned long addr, swp_entry_t entry, struct page *page)
{
inc_mm_counter(vma->vm_mm, anon_rss);
get_page(page);
set_pte_at(vma->vm_mm, addr, pte,
pte_mkold(mk_pte(page, vma->vm_page_prot)));
page_add_anon_rmap(page, vma, addr);
swap_free(entry);
/*
* Move the page to the active list so it is not
* immediately swapped out again after swapon.
*/
activate_page(page);
}
/*
* Mark a page as having seen activity.
*
* inactive,unreferenced -> inactive,referenced
* inactive,referenced -> active,unreferenced
* active,unreferenced -> active,referenced
*/
void mark_page_accessed(struct page *page)
{
if (!PageActive(page) && !PageUnevictable(page) &&
PageReferenced(page)) {
if (PageLRU(page))
activate_page(page);
else if (PageIONBacked(page))
SetPageActive(page);
else
return;
ClearPageReferenced(page);
} else if (!PageReferenced(page)) {
SetPageReferenced(page);
if (PageIONBacked(page) && PageActive(page))
ion_activate_page(page);
}
}
static int unuse_mm(struct mm_struct *mm,
swp_entry_t entry, struct page *page)
{
struct vm_area_struct *vma;
int ret = 0;
if (!down_read_trylock(&mm->mmap_sem)) {
/*
* Activate page so shrink_inactive_list is unlikely to unmap
* its ptes while lock is dropped, so swapoff can make progress.
*/
activate_page(page);
unlock_page(page);
down_read(&mm->mmap_sem);
lock_page(page);
}
for (vma = mm->mmap; vma; vma = vma->vm_next) {
if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
break;
}
up_read(&mm->mmap_sem);
return (ret < 0)? ret: 0;
}
