@@ -326,6 +326,7 @@ static inline void page_init_poison(struct page *page, size_t size)
PAGEFLAG(Dirty, dirty, PF_HEAD) TESTSCFLAG(Dirty, dirty, PF_HEAD)
__CLEARPAGEFLAG(Dirty, dirty, PF_HEAD)
PAGEFLAG(LRU, lru, PF_HEAD) __CLEARPAGEFLAG(LRU, lru, PF_HEAD)
+ TESTCLEARFLAG(LRU, lru, PF_HEAD)
PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD)
TESTCLEARFLAG(Active, active, PF_HEAD)
PAGEFLAG(Workingset, workingset, PF_HEAD)
@@ -108,13 +108,12 @@ void mlock_vma_page(struct page *page)
*/
static bool __munlock_isolate_lru_page(struct page *page, bool getpage)
{
- if (PageLRU(page)) {
+ if (TestClearPageLRU(page)) {
struct lruvec *lruvec;
lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
if (getpage)
get_page(page);
- ClearPageLRU(page);
del_page_from_lru_list(page, lruvec, page_lru(page));
return true;
}
@@ -83,10 +83,9 @@ static void __page_cache_release(struct page *page)
struct lruvec *lruvec;
unsigned long flags;
+ __ClearPageLRU(page);
spin_lock_irqsave(&pgdat->lru_lock, flags);
lruvec = mem_cgroup_page_lruvec(page, pgdat);
- VM_BUG_ON_PAGE(!PageLRU(page), page);
- __ClearPageLRU(page);
del_page_from_lru_list(page, lruvec, page_off_lru(page));
spin_unlock_irqrestore(&pgdat->lru_lock, flags);
}
@@ -877,9 +876,8 @@ void release_pages(struct page **pages, int nr)
spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
}
- lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
- VM_BUG_ON_PAGE(!PageLRU(page), page);
__ClearPageLRU(page);
+ lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
del_page_from_lru_list(page, lruvec, page_off_lru(page));
}
@@ -1547,16 +1547,16 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode)
{
int ret = -EINVAL;
- /* Only take pages on the LRU. */
- if (!PageLRU(page))
- return ret;
-
/* Compaction should not handle unevictable pages but CMA can do so */
if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))
return ret;
ret = -EBUSY;
+ /* Only take pages on the LRU. */
+ if (!PageLRU(page))
+ return ret;
+
/*
* To minimise LRU disruption, the caller can indicate that it only
* wants to isolate pages it will be able to operate on without
@@ -1670,8 +1670,6 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
page = lru_to_page(src);
prefetchw_prev_lru_page(page, src, flags);
- VM_BUG_ON_PAGE(!PageLRU(page), page);
-
nr_pages = compound_nr(page);
total_scan += nr_pages;
@@ -1768,21 +1766,19 @@ int isolate_lru_page(struct page *page)
VM_BUG_ON_PAGE(!page_count(page), page);
WARN_RATELIMIT(PageTail(page), "trying to isolate tail page");
- if (PageLRU(page)) {
+ if (TestClearPageLRU(page)) {
pg_data_t *pgdat = page_pgdat(page);
struct lruvec *lruvec;
+ int lru = page_lru(page);
- spin_lock_irq(&pgdat->lru_lock);
+ get_page(page);
lruvec = mem_cgroup_page_lruvec(page, pgdat);
- if (PageLRU(page)) {
- int lru = page_lru(page);
- get_page(page);
- ClearPageLRU(page);
- del_page_from_lru_list(page, lruvec, lru);
- ret = 0;
- }
+ spin_lock_irq(&pgdat->lru_lock);
+ del_page_from_lru_list(page, lruvec, lru);
spin_unlock_irq(&pgdat->lru_lock);
+ ret = 0;
}
+
return ret;
}
Combine PageLRU check and ClearPageLRU into a function by new introduced func TestClearPageLRU. This function will be used as page isolation precondition to prevent other isolations some where else. Then there are may non PageLRU page on lru list, need to remove BUG checking accordingly. Hugh Dickins pointed that __page_cache_release and release_pages has no need to do atomic clear bit since no user on the page at that moment. and no need get_page() before lru bit clear in isolate_lru_page, since it '(1) Must be called with an elevated refcount on the page'. As Andrew Morton mentioned this change would dirty cacheline for page isn't on LRU. But the lost would be acceptable with Rong Chen <rong.a.chen@intel.com> report: https://lkml.org/lkml/2020/3/4/173 Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-kernel@vger.kernel.org Cc: cgroups@vger.kernel.org Cc: linux-mm@kvack.org --- include/linux/page-flags.h | 1 + mm/mlock.c | 3 +-- mm/swap.c | 6 ++---- mm/vmscan.c | 26 +++++++++++--------------- 4 files changed, 15 insertions(+), 21 deletions(-)