From: Muchun Song <songmuchun@bytedance.com> To: akpm@linux-foundation.org, hannes@cmpxchg.org, longman@redhat.com, mhocko@kernel.org, roman.gushchin@linux.dev, shakeelb@google.com Cc: cgroups@vger.kernel.org, duanxiongchun@bytedance.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song <songmuchun@bytedance.com> Subject: [PATCH v6 11/11] mm: lru: use lruvec lock to serialize memcg changes Date: Tue, 21 Jun 2022 20:56:58 +0800 [thread overview] Message-ID: <20220621125658.64935-12-songmuchun@bytedance.com> (raw) In-Reply-To: <20220621125658.64935-1-songmuchun@bytedance.com> As described by commit fc574c23558c ("mm/swap.c: serialize memcg changes in pagevec_lru_move_fn"), TestClearPageLRU() aims to serialize mem_cgroup_move_account() during pagevec_lru_move_fn(). Now folio_lruvec_lock*() has the ability to detect whether page memcg has been changed. So we can use lruvec lock to serialize mem_cgroup_move_account() during pagevec_lru_move_fn(). This change is a partial revert of the commit fc574c23558c ("mm/swap.c: serialize memcg changes in pagevec_lru_move_fn"). And pagevec_lru_move_fn() is more hot compare with mem_cgroup_move_account(), removing an atomic operation would be an optimization. Also this change would not dirty cacheline for a page which isn't on the LRU. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- mm/memcontrol.c | 34 ++++++++++++++++++++++++++++++++++ mm/swap.c | 32 +++++++++++++++----------------- mm/vmscan.c | 16 +++++++--------- 3 files changed, 56 insertions(+), 26 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 803dbdf5f233..85adc43c5a25 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1330,10 +1330,39 @@ struct lruvec *folio_lruvec_lock(struct folio *folio) lruvec = folio_lruvec(folio); spin_lock(&lruvec->lru_lock); + /* + * The memcg of the page can be changed by any the following routines: + * + * 1) mem_cgroup_move_account() or + * 2) memcg_reparent_objcgs() + * + * The possible bad scenario would like: + * + * CPU0: CPU1: CPU2: + * lruvec = folio_lruvec() + * + * if (!isolate_lru_page()) + * mem_cgroup_move_account() + * + * memcg_reparent_objcgs() + * + * spin_lock(&lruvec->lru_lock) + * ^^^^^^ + * wrong lock + * + * Either CPU1 or CPU2 can change page memcg, so we need to check + * whether page memcg is changed, if so, we should reacquire the + * new lruvec lock. + */ if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) { spin_unlock(&lruvec->lru_lock); goto retry; } + + /* + * When we reach here, it means that the folio_memcg(folio) is + * stable. + */ rcu_read_unlock(); return lruvec; @@ -1361,6 +1390,7 @@ struct lruvec *folio_lruvec_lock_irq(struct folio *folio) lruvec = folio_lruvec(folio); spin_lock_irq(&lruvec->lru_lock); + /* See the comments in folio_lruvec_lock(). */ if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) { spin_unlock_irq(&lruvec->lru_lock); goto retry; @@ -1394,6 +1424,7 @@ struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio, lruvec = folio_lruvec(folio); spin_lock_irqsave(&lruvec->lru_lock, *flags); + /* See the comments in folio_lruvec_lock(). */ if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) { spin_unlock_irqrestore(&lruvec->lru_lock, *flags); goto retry; @@ -5809,7 +5840,10 @@ static int mem_cgroup_move_account(struct page *page, obj_cgroup_put(rcu_dereference(from->objcg)); rcu_read_unlock(); + /* See the comments in folio_lruvec_lock(). */ + spin_lock(&from_vec->lru_lock); folio->memcg_data = (unsigned long)rcu_access_pointer(to->objcg); + spin_unlock(&from_vec->lru_lock); __folio_memcg_unlock(from); diff --git a/mm/swap.c b/mm/swap.c index 987dcbd93ffa..0fc59409e27d 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -196,6 +196,7 @@ static void lru_add_fn(struct lruvec *lruvec, struct folio *folio) VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); + folio_set_lru(folio); /* * Is an smp_mb__after_atomic() still required here, before * folio_evictable() tests the mlocked flag, to rule out the possibility @@ -238,14 +239,8 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) for (i = 0; i < folio_batch_count(fbatch); i++) { struct folio *folio = fbatch->folios[i]; - /* block memcg migration while the folio moves between lru */ - if (move_fn != lru_add_fn && !folio_test_clear_lru(folio)) - continue; - lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags); move_fn(lruvec, folio); - - folio_set_lru(folio); } if (lruvec) @@ -265,7 +260,7 @@ static void folio_batch_add_and_move(struct folio_batch *fbatch, static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio) { - if (!folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && !folio_test_unevictable(folio)) { lruvec_del_folio(lruvec, folio); folio_clear_active(folio); lruvec_add_folio_tail(lruvec, folio); @@ -348,7 +343,8 @@ void lru_note_cost_folio(struct folio *folio) static void folio_activate_fn(struct lruvec *lruvec, struct folio *folio) { - if (!folio_test_active(folio) && !folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && !folio_test_active(folio) && + !folio_test_unevictable(folio)) { long nr_pages = folio_nr_pages(folio); lruvec_del_folio(lruvec, folio); @@ -394,12 +390,9 @@ static void folio_activate(struct folio *folio) { struct lruvec *lruvec; - if (folio_test_clear_lru(folio)) { - lruvec = folio_lruvec_lock_irq(folio); - folio_activate_fn(lruvec, folio); - lruvec_unlock_irq(lruvec); - folio_set_lru(folio); - } + lruvec = folio_lruvec_lock_irq(folio); + folio_activate_fn(lruvec, folio); + lruvec_unlock_irq(lruvec); } #endif @@ -542,6 +535,9 @@ static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio) bool active = folio_test_active(folio); long nr_pages = folio_nr_pages(folio); + if (!folio_test_lru(folio)) + return; + if (folio_test_unevictable(folio)) return; @@ -580,7 +576,8 @@ static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio) static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio) { - if (folio_test_active(folio) && !folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && folio_test_active(folio) && + !folio_test_unevictable(folio)) { long nr_pages = folio_nr_pages(folio); lruvec_del_folio(lruvec, folio); @@ -596,8 +593,9 @@ static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio) static void lru_lazyfree_fn(struct lruvec *lruvec, struct folio *folio) { - if (folio_test_anon(folio) && folio_test_swapbacked(folio) && - !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && folio_test_anon(folio) && + folio_test_swapbacked(folio) && !folio_test_swapcache(folio) && + !folio_test_unevictable(folio)) { long nr_pages = folio_nr_pages(folio); lruvec_del_folio(lruvec, folio); diff --git a/mm/vmscan.c b/mm/vmscan.c index 51b1607c81e4..11e1f6fc5898 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4864,21 +4864,19 @@ void check_move_unevictable_pages(struct pagevec *pvec) if (PageTransTail(page)) continue; - nr_pages = thp_nr_pages(page); + nr_pages = folio_nr_pages(folio); pgscanned += nr_pages; - /* block memcg migration during page moving between lru */ - if (!TestClearPageLRU(page)) + lruvec = folio_lruvec_relock_irq(folio, lruvec); + if (!folio_test_lru(folio) || !folio_test_unevictable(folio)) continue; - lruvec = folio_lruvec_relock_irq(folio, lruvec); - if (page_evictable(page) && PageUnevictable(page)) { - del_page_from_lru_list(page, lruvec); - ClearPageUnevictable(page); - add_page_to_lru_list(page, lruvec); + if (folio_evictable(folio)) { + lruvec_del_folio(lruvec, folio); + folio_clear_unevictable(folio); + lruvec_add_folio(lruvec, folio); pgrescued += nr_pages; } - SetPageLRU(page); } if (lruvec) { -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> To: akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, roman.gushchin-fxUVXftIFDnyG1zEObXtfA@public.gmane.org, shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, duanxiongchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> Subject: [PATCH v6 11/11] mm: lru: use lruvec lock to serialize memcg changes Date: Tue, 21 Jun 2022 20:56:58 +0800 [thread overview] Message-ID: <20220621125658.64935-12-songmuchun@bytedance.com> (raw) In-Reply-To: <20220621125658.64935-1-songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> As described by commit fc574c23558c ("mm/swap.c: serialize memcg changes in pagevec_lru_move_fn"), TestClearPageLRU() aims to serialize mem_cgroup_move_account() during pagevec_lru_move_fn(). Now folio_lruvec_lock*() has the ability to detect whether page memcg has been changed. So we can use lruvec lock to serialize mem_cgroup_move_account() during pagevec_lru_move_fn(). This change is a partial revert of the commit fc574c23558c ("mm/swap.c: serialize memcg changes in pagevec_lru_move_fn"). And pagevec_lru_move_fn() is more hot compare with mem_cgroup_move_account(), removing an atomic operation would be an optimization. Also this change would not dirty cacheline for a page which isn't on the LRU. Signed-off-by: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> --- mm/memcontrol.c | 34 ++++++++++++++++++++++++++++++++++ mm/swap.c | 32 +++++++++++++++----------------- mm/vmscan.c | 16 +++++++--------- 3 files changed, 56 insertions(+), 26 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 803dbdf5f233..85adc43c5a25 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1330,10 +1330,39 @@ struct lruvec *folio_lruvec_lock(struct folio *folio) lruvec = folio_lruvec(folio); spin_lock(&lruvec->lru_lock); + /* + * The memcg of the page can be changed by any the following routines: + * + * 1) mem_cgroup_move_account() or + * 2) memcg_reparent_objcgs() + * + * The possible bad scenario would like: + * + * CPU0: CPU1: CPU2: + * lruvec = folio_lruvec() + * + * if (!isolate_lru_page()) + * mem_cgroup_move_account() + * + * memcg_reparent_objcgs() + * + * spin_lock(&lruvec->lru_lock) + * ^^^^^^ + * wrong lock + * + * Either CPU1 or CPU2 can change page memcg, so we need to check + * whether page memcg is changed, if so, we should reacquire the + * new lruvec lock. + */ if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) { spin_unlock(&lruvec->lru_lock); goto retry; } + + /* + * When we reach here, it means that the folio_memcg(folio) is + * stable. + */ rcu_read_unlock(); return lruvec; @@ -1361,6 +1390,7 @@ struct lruvec *folio_lruvec_lock_irq(struct folio *folio) lruvec = folio_lruvec(folio); spin_lock_irq(&lruvec->lru_lock); + /* See the comments in folio_lruvec_lock(). */ if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) { spin_unlock_irq(&lruvec->lru_lock); goto retry; @@ -1394,6 +1424,7 @@ struct lruvec *folio_lruvec_lock_irqsave(struct folio *folio, lruvec = folio_lruvec(folio); spin_lock_irqsave(&lruvec->lru_lock, *flags); + /* See the comments in folio_lruvec_lock(). */ if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) { spin_unlock_irqrestore(&lruvec->lru_lock, *flags); goto retry; @@ -5809,7 +5840,10 @@ static int mem_cgroup_move_account(struct page *page, obj_cgroup_put(rcu_dereference(from->objcg)); rcu_read_unlock(); + /* See the comments in folio_lruvec_lock(). */ + spin_lock(&from_vec->lru_lock); folio->memcg_data = (unsigned long)rcu_access_pointer(to->objcg); + spin_unlock(&from_vec->lru_lock); __folio_memcg_unlock(from); diff --git a/mm/swap.c b/mm/swap.c index 987dcbd93ffa..0fc59409e27d 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -196,6 +196,7 @@ static void lru_add_fn(struct lruvec *lruvec, struct folio *folio) VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); + folio_set_lru(folio); /* * Is an smp_mb__after_atomic() still required here, before * folio_evictable() tests the mlocked flag, to rule out the possibility @@ -238,14 +239,8 @@ static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) for (i = 0; i < folio_batch_count(fbatch); i++) { struct folio *folio = fbatch->folios[i]; - /* block memcg migration while the folio moves between lru */ - if (move_fn != lru_add_fn && !folio_test_clear_lru(folio)) - continue; - lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags); move_fn(lruvec, folio); - - folio_set_lru(folio); } if (lruvec) @@ -265,7 +260,7 @@ static void folio_batch_add_and_move(struct folio_batch *fbatch, static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio) { - if (!folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && !folio_test_unevictable(folio)) { lruvec_del_folio(lruvec, folio); folio_clear_active(folio); lruvec_add_folio_tail(lruvec, folio); @@ -348,7 +343,8 @@ void lru_note_cost_folio(struct folio *folio) static void folio_activate_fn(struct lruvec *lruvec, struct folio *folio) { - if (!folio_test_active(folio) && !folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && !folio_test_active(folio) && + !folio_test_unevictable(folio)) { long nr_pages = folio_nr_pages(folio); lruvec_del_folio(lruvec, folio); @@ -394,12 +390,9 @@ static void folio_activate(struct folio *folio) { struct lruvec *lruvec; - if (folio_test_clear_lru(folio)) { - lruvec = folio_lruvec_lock_irq(folio); - folio_activate_fn(lruvec, folio); - lruvec_unlock_irq(lruvec); - folio_set_lru(folio); - } + lruvec = folio_lruvec_lock_irq(folio); + folio_activate_fn(lruvec, folio); + lruvec_unlock_irq(lruvec); } #endif @@ -542,6 +535,9 @@ static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio) bool active = folio_test_active(folio); long nr_pages = folio_nr_pages(folio); + if (!folio_test_lru(folio)) + return; + if (folio_test_unevictable(folio)) return; @@ -580,7 +576,8 @@ static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio) static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio) { - if (folio_test_active(folio) && !folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && folio_test_active(folio) && + !folio_test_unevictable(folio)) { long nr_pages = folio_nr_pages(folio); lruvec_del_folio(lruvec, folio); @@ -596,8 +593,9 @@ static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio) static void lru_lazyfree_fn(struct lruvec *lruvec, struct folio *folio) { - if (folio_test_anon(folio) && folio_test_swapbacked(folio) && - !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) { + if (folio_test_lru(folio) && folio_test_anon(folio) && + folio_test_swapbacked(folio) && !folio_test_swapcache(folio) && + !folio_test_unevictable(folio)) { long nr_pages = folio_nr_pages(folio); lruvec_del_folio(lruvec, folio); diff --git a/mm/vmscan.c b/mm/vmscan.c index 51b1607c81e4..11e1f6fc5898 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4864,21 +4864,19 @@ void check_move_unevictable_pages(struct pagevec *pvec) if (PageTransTail(page)) continue; - nr_pages = thp_nr_pages(page); + nr_pages = folio_nr_pages(folio); pgscanned += nr_pages; - /* block memcg migration during page moving between lru */ - if (!TestClearPageLRU(page)) + lruvec = folio_lruvec_relock_irq(folio, lruvec); + if (!folio_test_lru(folio) || !folio_test_unevictable(folio)) continue; - lruvec = folio_lruvec_relock_irq(folio, lruvec); - if (page_evictable(page) && PageUnevictable(page)) { - del_page_from_lru_list(page, lruvec); - ClearPageUnevictable(page); - add_page_to_lru_list(page, lruvec); + if (folio_evictable(folio)) { + lruvec_del_folio(lruvec, folio); + folio_clear_unevictable(folio); + lruvec_add_folio(lruvec, folio); pgrescued += nr_pages; } - SetPageLRU(page); } if (lruvec) { -- 2.11.0
next prev parent reply other threads:[~2022-06-21 12:59 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-06-21 12:56 [PATCH v6 00/11] Use obj_cgroup APIs to charge the LRU pages Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 01/11] mm: memcontrol: remove dead code and comments Muchun Song 2022-06-21 12:56 ` [PATCH v6 02/11] mm: rename unlock_page_lruvec{_irq, _irqrestore} to lruvec_unlock{_irq, _irqrestore} Muchun Song 2022-06-21 12:56 ` [PATCH v6 03/11] mm: memcontrol: prepare objcg API for non-kmem usage Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 04/11] mm: memcontrol: make lruvec lock safe when LRU pages are reparented Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 05/11] mm: vmscan: rework move_pages_to_lru() Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 06/11] mm: thp: make split queue lock safe when LRU pages are reparented Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 07/11] mm: memcontrol: make all the callers of {folio,page}_memcg() safe Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 08/11] mm: memcontrol: introduce memcg_reparent_ops Muchun Song 2022-06-21 12:56 ` [PATCH v6 09/11] mm: memcontrol: use obj_cgroup APIs to charge the LRU pages Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` [PATCH v6 10/11] mm: lru: add VM_WARN_ON_ONCE_FOLIO to lru maintenance function Muchun Song 2022-06-21 12:56 ` Muchun Song 2022-06-21 12:56 ` Muchun Song [this message] 2022-06-21 12:56 ` [PATCH v6 11/11] mm: lru: use lruvec lock to serialize memcg changes Muchun Song 2022-06-26 10:32 ` [PATCH v6 00/11] Use obj_cgroup APIs to charge the LRU pages Yosry Ahmed 2022-06-26 10:32 ` Yosry Ahmed 2022-06-27 7:11 ` Muchun Song 2022-06-27 7:11 ` Muchun Song 2022-06-27 8:05 ` Yosry Ahmed 2022-06-27 8:05 ` Yosry Ahmed 2022-06-27 10:13 ` Muchun Song 2022-06-27 10:13 ` Muchun Song 2022-06-27 16:46 ` Yosry Ahmed 2022-06-27 16:46 ` Yosry Ahmed 2022-06-28 1:24 ` Roman Gushchin 2022-06-28 1:24 ` Roman Gushchin 2022-06-28 1:31 ` Yosry Ahmed 2022-06-28 1:31 ` Yosry Ahmed 2022-06-28 1:37 ` Roman Gushchin 2022-06-28 1:37 ` Roman Gushchin 2022-06-28 1:45 ` Yosry Ahmed 2022-06-28 1:45 ` Yosry Ahmed 2022-06-27 10:43 ` Mika Penttilä 2022-06-27 10:43 ` Mika Penttilä 2022-06-27 16:49 ` Yosry Ahmed 2022-06-27 16:49 ` Yosry Ahmed 2022-07-07 22:14 ` Yosry Ahmed 2022-07-07 22:14 ` Yosry Ahmed 2022-07-08 6:52 ` Muchun Song 2022-07-08 6:52 ` Muchun Song 2022-07-08 9:26 ` Yosry Ahmed 2022-07-08 9:26 ` Yosry Ahmed 2022-07-09 5:51 ` Muchun Song 2022-07-09 9:23 ` Yosry Ahmed 2022-07-09 9:23 ` Yosry Ahmed 2022-07-03 23:23 ` Andrew Morton 2022-07-03 23:23 ` Andrew Morton
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