static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
void *arg)
{
enum lru_list lru;
int was_unevictable = TestClearPageUnevictable(page);
VM_BUG_ON_PAGE(PageLRU(page), page);
SetPageLRU(page);
/*
* Page becomes evictable in two ways:
* 1) Within LRU lock [munlock_vma_pages() and __munlock_pagevec()].
* 2) Before acquiring LRU lock to put the page to correct LRU and then
* a) do PageLRU check with lock [check_move_unevictable_pages]
* b) do PageLRU check before lock [clear_page_mlock]
*
* (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
* following strict ordering:
*
* #0: __pagevec_lru_add_fn #1: clear_page_mlock
*
* SetPageLRU() TestClearPageMlocked()
* smp_mb() // explicit ordering // above provides strict
* // ordering
* PageMlocked() PageLRU()
*
*
* if '#1' does not observe setting of PG_lru by '#0' and fails
* isolation, the explicit barrier will make sure that page_evictable
* check will put the page in correct LRU. Without smp_mb(), SetPageLRU
* can be reordered after PageMlocked check and can make '#1' to fail
* the isolation of the page whose Mlocked bit is cleared (#0 is also
* looking at the same page) and the evictable page will be stranded
* in an unevictable LRU.
*/
smp_mb();
if (page_evictable(page)) {
lru = page_lru(page);
update_page_reclaim_stat(lruvec, page_is_file_cache(page),
PageActive(page));
if (was_unevictable)
count_vm_event(UNEVICTABLE_PGRESCUED);
} else {
lru = LRU_UNEVICTABLE;
ClearPageActive(page);
SetPageUnevictable(page);
if (!was_unevictable)
count_vm_event(UNEVICTABLE_PGCULLED);
}
add_page_to_lru_list(page, lruvec, lru);
trace_mm_lru_insertion(page, lru);
}
static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
void *arg)
{
int file = page_is_file_cache(page);
int active = PageActive(page);
enum lru_list lru = page_lru(page);
VM_BUG_ON(PageLRU(page));
SetPageLRU(page);
add_page_to_lru_list(page, lruvec, lru);
update_page_reclaim_stat(lruvec, file, active);
trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page));
}
