On 20/08/2019 12.48, Alex Shi wrote:
Now we repeatly assign the lruvec->pgdat in memcg. Will remove the assignment in lruvec getting function after very points are protected.Signed-off-by: Alex Shi <alex....@linux.alibaba.com> Cc: Johannes Weiner <han...@cmpxchg.org> Cc: Michal Hocko <mho...@kernel.org> Cc: Vladimir Davydov <vdavydov....@gmail.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Tejun Heo <t...@kernel.org> Cc: cgro...@vger.kernel.org Cc: linux...@kvack.org Cc: linux-kernel@vger.kernel.org --- mm/memcontrol.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index e8a1b0d95ba8..19fd911e8098 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2550,12 +2550,12 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) static void lock_page_lru(struct page *page, int *isolated) { pg_data_t *pgdat = page_pgdat(page); + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat);
What protects lruvec from freeing at this point? After reading resolving lruvec page could be moved and cgroup deleted. In this old patches I've used RCU for that: https://lkml.org/lkml/2012/2/20/276 Pointer to lruvec should be resolved under disabled irq. Not sure this works these days.
- spin_lock_irq(&pgdat->lruvec.lru_lock); + spin_lock_irq(&lruvec->lru_lock); + sync_lruvec_pgdat(lruvec, pgdat); if (PageLRU(page)) { - struct lruvec *lruvec;- lruvec = mem_cgroup_page_lruvec(page, pgdat);ClearPageLRU(page); del_page_from_lru_list(page, lruvec, page_lru(page)); *isolated = 1; @@ -2566,16 +2566,14 @@ static void lock_page_lru(struct page *page, int *isolated) static void unlock_page_lru(struct page *page, int isolated) { pg_data_t *pgdat = page_pgdat(page); + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat);if (isolated) {- struct lruvec *lruvec; - - lruvec = mem_cgroup_page_lruvec(page, pgdat); VM_BUG_ON_PAGE(PageLRU(page), page); SetPageLRU(page); add_page_to_lru_list(page, lruvec, page_lru(page)); } - spin_unlock_irq(&pgdat->lruvec.lru_lock); + spin_unlock_irq(&lruvec->lru_lock); }static void commit_charge(struct page *page, struct mem_cgroup *memcg,
