mm: add __clear_page_lru_flags() to replace page_off_lru()
Similar to page_off_lru(), the new function does non-atomic clearing
of PageLRU() in addition to PageActive() and PageUnevictable(), on a
page that has no references left.
If PageActive() and PageUnevictable() are both set, refuse to clear
either and leave them to bad_page(). This is a behavior change that
is meant to help debug.
Link: https://lore.kernel.org/linux-mm/20201207220949.830352-7-yuzhao@google.com/
Link: https://lkml.kernel.org/r/20210122220600.906146-7-yuzhao@google.com
Signed-off-by: Yu Zhao <yuzhao@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/mm_inline.h b/include/linux/mm_inline.h
index ffacc62..ef3fd79 100644
--- a/include/linux/mm_inline.h
+++ b/include/linux/mm_inline.h
@@ -61,27 +61,19 @@
}
/**
- * page_off_lru - which LRU list was page on? clearing its lru flags.
- * @page: the page to test
- *
- * Returns the LRU list a page was on, as an index into the array of LRU
- * lists; and clears its Unevictable or Active flags, ready for freeing.
+ * __clear_page_lru_flags - clear page lru flags before releasing a page
+ * @page: the page that was on lru and now has a zero reference
*/
-static __always_inline enum lru_list page_off_lru(struct page *page)
+static __always_inline void __clear_page_lru_flags(struct page *page)
{
- enum lru_list lru;
+ __ClearPageLRU(page);
- if (PageUnevictable(page)) {
- __ClearPageUnevictable(page);
- lru = LRU_UNEVICTABLE;
- } else {
- lru = page_lru_base_type(page);
- if (PageActive(page)) {
- __ClearPageActive(page);
- lru += LRU_ACTIVE;
- }
- }
- return lru;
+ /* this shouldn't happen, so leave the flags to bad_page() */
+ if (PageActive(page) && PageUnevictable(page))
+ return;
+
+ __ClearPageActive(page);
+ __ClearPageUnevictable(page);
}
/**
diff --git a/mm/swap.c b/mm/swap.c
index ff910f6..1455fa5 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -84,9 +84,8 @@
lruvec = lock_page_lruvec_irqsave(page, &flags);
VM_BUG_ON_PAGE(!PageLRU(page), page);
- __ClearPageLRU(page);
del_page_from_lru_list(page, lruvec);
- page_off_lru(page);
+ __clear_page_lru_flags(page);
unlock_page_lruvec_irqrestore(lruvec, flags);
}
__ClearPageWaiters(page);
@@ -911,9 +910,8 @@
lock_batch = 0;
VM_BUG_ON_PAGE(!PageLRU(page), page);
- __ClearPageLRU(page);
del_page_from_lru_list(page, lruvec);
- page_off_lru(page);
+ __clear_page_lru_flags(page);
}
__ClearPageWaiters(page);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 7c65d47..452dd38 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1849,8 +1849,7 @@
SetPageLRU(page);
if (unlikely(put_page_testzero(page))) {
- __ClearPageLRU(page);
- __ClearPageActive(page);
+ __clear_page_lru_flags(page);
if (unlikely(PageCompound(page))) {
spin_unlock_irq(&lruvec->lru_lock);
