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Message-ID: <CAKgT0Ud+Dj-Q8Sxv8eDQhjM3fFHwnU_ZFEVG54debBennUmxAg@mail.gmail.com>
Date: Fri, 17 Jul 2020 14:38:29 -0700
From: Alexander Duyck <alexander.duyck@...il.com>
To: Alex Shi <alex.shi@...ux.alibaba.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Mel Gorman <mgorman@...hsingularity.net>,
Tejun Heo <tj@...nel.org>, Hugh Dickins <hughd@...gle.com>,
Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
Daniel Jordan <daniel.m.jordan@...cle.com>,
Yang Shi <yang.shi@...ux.alibaba.com>,
Matthew Wilcox <willy@...radead.org>,
Johannes Weiner <hannes@...xchg.org>,
kbuild test robot <lkp@...el.com>,
linux-mm <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>, cgroups@...r.kernel.org,
Shakeel Butt <shakeelb@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>,
Wei Yang <richard.weiyang@...il.com>,
"Kirill A. Shutemov" <kirill@...temov.name>,
Michal Hocko <mhocko@...nel.org>,
Vladimir Davydov <vdavydov.dev@...il.com>
Subject: Re: [PATCH v16 18/22] mm/lru: replace pgdat lru_lock with lruvec lock
On Fri, Jul 10, 2020 at 6:00 PM Alex Shi <alex.shi@...ux.alibaba.com> wrote:
>
> This patch moves per node lru_lock into lruvec, thus bring a lru_lock for
> each of memcg per node. So on a large machine, each of memcg don't
> have to suffer from per node pgdat->lru_lock competition. They could go
> fast with their self lru_lock.
>
> After move memcg charge before lru inserting, page isolation could
> serialize page's memcg, then per memcg lruvec lock is stable and could
> replace per node lru lock.
>
> According to Daniel Jordan's suggestion, I run 208 'dd' with on 104
> containers on a 2s * 26cores * HT box with a modefied case:
> https://git.kernel.org/pub/scm/linux/kernel/git/wfg/vm-scalability.git/tree/case-lru-file-readtwice
>
> With this and later patches, the readtwice performance increases about
> 80% within concurrent containers.
>
> Also add a debug func in locking which may give some clues if there are
> sth out of hands.
>
> Hugh Dickins helped on patch polish, thanks!
>
> Reported-by: kernel test robot <lkp@...el.com>
> Signed-off-by: Alex Shi <alex.shi@...ux.alibaba.com>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Johannes Weiner <hannes@...xchg.org>
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Vladimir Davydov <vdavydov.dev@...il.com>
> Cc: Yang Shi <yang.shi@...ux.alibaba.com>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
> Cc: Tejun Heo <tj@...nel.org>
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-mm@...ck.org
> Cc: cgroups@...r.kernel.org
> ---
> include/linux/memcontrol.h | 98 ++++++++++++++++++++++++++++++++++++++++++++
> include/linux/mmzone.h | 2 +
> mm/compaction.c | 67 +++++++++++++++++++-----------
> mm/huge_memory.c | 11 ++---
> mm/memcontrol.c | 63 +++++++++++++++++++++++++++-
> mm/mlock.c | 32 +++++++--------
> mm/mmzone.c | 1 +
> mm/swap.c | 100 +++++++++++++++++++++------------------------
> mm/vmscan.c | 70 +++++++++++++++++--------------
> 9 files changed, 310 insertions(+), 134 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index e77197a62809..6e670f991b42 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -411,6 +411,19 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
>
> struct mem_cgroup *get_mem_cgroup_from_page(struct page *page);
>
> +struct lruvec *lock_page_lruvec(struct page *page);
> +struct lruvec *lock_page_lruvec_irq(struct page *page);
> +struct lruvec *lock_page_lruvec_irqsave(struct page *page,
> + unsigned long *flags);
> +
> +#ifdef CONFIG_DEBUG_VM
> +void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page);
> +#else
> +static inline void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page)
> +{
> +}
> +#endif
> +
> static inline
> struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css){
> return css ? container_of(css, struct mem_cgroup, css) : NULL;
> @@ -892,6 +905,31 @@ static inline void mem_cgroup_put(struct mem_cgroup *memcg)
> {
> }
>
> +static inline struct lruvec *lock_page_lruvec(struct page *page)
> +{
> + struct pglist_data *pgdat = page_pgdat(page);
> +
> + spin_lock(&pgdat->__lruvec.lru_lock);
> + return &pgdat->__lruvec;
> +}
> +
> +static inline struct lruvec *lock_page_lruvec_irq(struct page *page)
> +{
> + struct pglist_data *pgdat = page_pgdat(page);
> +
> + spin_lock_irq(&pgdat->__lruvec.lru_lock);
> + return &pgdat->__lruvec;
> +}
> +
> +static inline struct lruvec *lock_page_lruvec_irqsave(struct page *page,
> + unsigned long *flagsp)
> +{
> + struct pglist_data *pgdat = page_pgdat(page);
> +
> + spin_lock_irqsave(&pgdat->__lruvec.lru_lock, *flagsp);
> + return &pgdat->__lruvec;
> +}
> +
> static inline struct mem_cgroup *
> mem_cgroup_iter(struct mem_cgroup *root,
> struct mem_cgroup *prev,
> @@ -1126,6 +1164,10 @@ static inline void count_memcg_page_event(struct page *page,
> void count_memcg_event_mm(struct mm_struct *mm, enum vm_event_item idx)
> {
> }
> +
> +static inline void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page)
> +{
> +}
> #endif /* CONFIG_MEMCG */
>
> /* idx can be of type enum memcg_stat_item or node_stat_item */
> @@ -1255,6 +1297,62 @@ static inline struct lruvec *parent_lruvec(struct lruvec *lruvec)
> return mem_cgroup_lruvec(memcg, lruvec_pgdat(lruvec));
> }
>
> +static inline void unlock_page_lruvec(struct lruvec *lruvec)
> +{
> + spin_unlock(&lruvec->lru_lock);
> +}
> +
> +static inline void unlock_page_lruvec_irq(struct lruvec *lruvec)
> +{
> + spin_unlock_irq(&lruvec->lru_lock);
> +}
> +
> +static inline void unlock_page_lruvec_irqrestore(struct lruvec *lruvec,
> + unsigned long flags)
> +{
> + spin_unlock_irqrestore(&lruvec->lru_lock, flags);
> +}
> +
> +/* Don't lock again iff page's lruvec locked */
> +static inline struct lruvec *relock_page_lruvec_irq(struct page *page,
> + struct lruvec *locked_lruvec)
> +{
> + struct pglist_data *pgdat = page_pgdat(page);
> + bool locked;
> +
> + rcu_read_lock();
> + locked = mem_cgroup_page_lruvec(page, pgdat) == locked_lruvec;
> + rcu_read_unlock();
> +
> + if (locked)
> + return locked_lruvec;
> +
> + if (locked_lruvec)
> + unlock_page_lruvec_irq(locked_lruvec);
> +
> + return lock_page_lruvec_irq(page);
> +}
> +
> +/* Don't lock again iff page's lruvec locked */
> +static inline struct lruvec *relock_page_lruvec_irqsave(struct page *page,
> + struct lruvec *locked_lruvec, unsigned long *flags)
> +{
> + struct pglist_data *pgdat = page_pgdat(page);
> + bool locked;
> +
> + rcu_read_lock();
> + locked = mem_cgroup_page_lruvec(page, pgdat) == locked_lruvec;
> + rcu_read_unlock();
> +
> + if (locked)
> + return locked_lruvec;
> +
> + if (locked_lruvec)
> + unlock_page_lruvec_irqrestore(locked_lruvec, *flags);
> +
> + return lock_page_lruvec_irqsave(page, flags);
> +}
> +
These relock functions have no users in this patch. It might make
sense and push this code to patch 19 in your series since that is
where they are first used. In addition they don't seem very efficient
as you already had to call mem_cgroup_page_lruvec once, why do it
again when you could just store the value and lock the new lruvec if
needed?
> #ifdef CONFIG_CGROUP_WRITEBACK
>
> struct wb_domain *mem_cgroup_wb_domain(struct bdi_writeback *wb);
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 14c668b7e793..36c1680efd90 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -261,6 +261,8 @@ struct lruvec {
> atomic_long_t nonresident_age;
> /* Refaults at the time of last reclaim cycle */
> unsigned long refaults;
> + /* per lruvec lru_lock for memcg */
> + spinlock_t lru_lock;
> /* Various lruvec state flags (enum lruvec_flags) */
> unsigned long flags;
Any reason for placing this here instead of at the end of the
structure? From what I can tell it looks like lruvec is already 128B
long so placing the lock on the end would put it into the next
cacheline which may provide some performance benefit since it is
likely to be bounced quite a bit.
> #ifdef CONFIG_MEMCG
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 2da2933fe56b..88bbd2e93895 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -787,7 +787,7 @@ static bool too_many_isolated(pg_data_t *pgdat)
> unsigned long nr_scanned = 0, nr_isolated = 0;
> struct lruvec *lruvec;
> unsigned long flags = 0;
> - bool locked = false;
> + struct lruvec *locked_lruvec = NULL;
> struct page *page = NULL, *valid_page = NULL;
> unsigned long start_pfn = low_pfn;
> bool skip_on_failure = false;
> @@ -847,11 +847,21 @@ static bool too_many_isolated(pg_data_t *pgdat)
> * contention, to give chance to IRQs. Abort completely if
> * a fatal signal is pending.
> */
> - if (!(low_pfn % SWAP_CLUSTER_MAX)
> - && compact_unlock_should_abort(&pgdat->lru_lock,
> - flags, &locked, cc)) {
> - low_pfn = 0;
> - goto fatal_pending;
> + if (!(low_pfn % SWAP_CLUSTER_MAX)) {
> + if (locked_lruvec) {
> + unlock_page_lruvec_irqrestore(locked_lruvec,
> + flags);
> + locked_lruvec = NULL;
> + }
> +
> + if (fatal_signal_pending(current)) {
> + cc->contended = true;
> +
> + low_pfn = 0;
> + goto fatal_pending;
> + }
> +
> + cond_resched();
> }
>
> if (!pfn_valid_within(low_pfn))
> @@ -922,10 +932,9 @@ static bool too_many_isolated(pg_data_t *pgdat)
> */
> if (unlikely(__PageMovable(page)) &&
> !PageIsolated(page)) {
> - if (locked) {
> - spin_unlock_irqrestore(&pgdat->lru_lock,
> - flags);
> - locked = false;
> + if (locked_lruvec) {
> + unlock_page_lruvec_irqrestore(locked_lruvec, flags);
> + locked_lruvec = NULL;
> }
>
> if (!isolate_movable_page(page, isolate_mode))
> @@ -966,10 +975,20 @@ static bool too_many_isolated(pg_data_t *pgdat)
> if (!TestClearPageLRU(page))
> goto isolate_fail_put;
>
> + rcu_read_lock();
> + lruvec = mem_cgroup_page_lruvec(page, pgdat);
> +
> /* If we already hold the lock, we can skip some rechecking */
> - if (!locked) {
> - locked = compact_lock_irqsave(&pgdat->lru_lock,
> - &flags, cc);
> + if (lruvec != locked_lruvec) {
> + if (locked_lruvec)
> + unlock_page_lruvec_irqrestore(locked_lruvec,
> + flags);
> +
> + compact_lock_irqsave(&lruvec->lru_lock, &flags, cc);
> + locked_lruvec = lruvec;
> + rcu_read_unlock();
> +
> + lruvec_memcg_debug(lruvec, page);
>
> /* Try get exclusive access under lock */
> if (!skip_updated) {
> @@ -988,9 +1007,8 @@ static bool too_many_isolated(pg_data_t *pgdat)
> SetPageLRU(page);
> goto isolate_fail_put;
> }
> - }
> -
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> + } else
> + rcu_read_unlock();
>
> /* The whole page is taken off the LRU; skip the tail pages. */
> if (PageCompound(page))
> @@ -1023,9 +1041,9 @@ static bool too_many_isolated(pg_data_t *pgdat)
>
> isolate_fail_put:
> /* Avoid potential deadlock in freeing page under lru_lock */
> - if (locked) {
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> - locked = false;
> + if (locked_lruvec) {
> + unlock_page_lruvec_irqrestore(locked_lruvec, flags);
> + locked_lruvec = NULL;
> }
> put_page(page);
>
> @@ -1039,9 +1057,10 @@ static bool too_many_isolated(pg_data_t *pgdat)
> * page anyway.
> */
> if (nr_isolated) {
> - if (locked) {
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> - locked = false;
> + if (locked_lruvec) {
> + unlock_page_lruvec_irqrestore(locked_lruvec,
> + flags);
> + locked_lruvec = NULL;
> }
> putback_movable_pages(&cc->migratepages);
> cc->nr_migratepages = 0;
> @@ -1068,8 +1087,8 @@ static bool too_many_isolated(pg_data_t *pgdat)
> page = NULL;
>
> isolate_abort:
> - if (locked)
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> + if (locked_lruvec)
> + unlock_page_lruvec_irqrestore(locked_lruvec, flags);
> if (page) {
> SetPageLRU(page);
> put_page(page);
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4fe7b92c9330..1ff0c1ff6a52 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2346,7 +2346,7 @@ static void lru_add_page_tail(struct page *head, struct page *page_tail,
> VM_BUG_ON_PAGE(!PageHead(head), head);
> VM_BUG_ON_PAGE(PageCompound(page_tail), head);
> VM_BUG_ON_PAGE(PageLRU(page_tail), head);
> - lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
> + lockdep_assert_held(&lruvec->lru_lock);
>
> if (list) {
> /* page reclaim is reclaiming a huge page */
> @@ -2429,7 +2429,6 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> pgoff_t end)
> {
> struct page *head = compound_head(page);
> - pg_data_t *pgdat = page_pgdat(head);
> struct lruvec *lruvec;
> struct address_space *swap_cache = NULL;
> unsigned long offset = 0;
> @@ -2446,10 +2445,8 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> xa_lock(&swap_cache->i_pages);
> }
>
> - /* prevent PageLRU to go away from under us, and freeze lru stats */
> - spin_lock(&pgdat->lru_lock);
> -
> - lruvec = mem_cgroup_page_lruvec(head, pgdat);
> + /* lock lru list/PageCompound, ref freezed by page_ref_freeze */
> + lruvec = lock_page_lruvec(head);
>
> for (i = HPAGE_PMD_NR - 1; i >= 1; i--) {
> __split_huge_page_tail(head, i, lruvec, list);
> @@ -2470,7 +2467,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
> }
>
> ClearPageCompound(head);
> - spin_unlock(&pgdat->lru_lock);
> + unlock_page_lruvec(lruvec);
> /* Caller disabled irqs, so they are still disabled here */
>
> split_page_owner(head, HPAGE_PMD_ORDER);
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index fde47272b13c..d5e56be42f21 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1196,6 +1196,19 @@ int mem_cgroup_scan_tasks(struct mem_cgroup *memcg,
> return ret;
> }
>
> +#ifdef CONFIG_DEBUG_VM
> +void lruvec_memcg_debug(struct lruvec *lruvec, struct page *page)
> +{
> + if (mem_cgroup_disabled())
> + return;
> +
> + if (!page->mem_cgroup)
> + VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != root_mem_cgroup, page);
> + else
> + VM_BUG_ON_PAGE(lruvec_memcg(lruvec) != page->mem_cgroup, page);
> +}
> +#endif
> +
> /**
> * mem_cgroup_page_lruvec - return lruvec for isolating/putting an LRU page
> * @page: the page
> @@ -1215,7 +1228,8 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd
> goto out;
> }
>
> - memcg = page->mem_cgroup;
> + VM_BUG_ON_PAGE(PageTail(page), page);
> + memcg = READ_ONCE(page->mem_cgroup);
> /*
> * Swapcache readahead pages are added to the LRU - and
> * possibly migrated - before they are charged.
> @@ -1236,6 +1250,51 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd
> return lruvec;
> }
>
> +struct lruvec *lock_page_lruvec(struct page *page)
> +{
> + struct lruvec *lruvec;
> + struct pglist_data *pgdat = page_pgdat(page);
> +
> + rcu_read_lock();
> + lruvec = mem_cgroup_page_lruvec(page, pgdat);
> + spin_lock(&lruvec->lru_lock);
> + rcu_read_unlock();
> +
> + lruvec_memcg_debug(lruvec, page);
> +
> + return lruvec;
> +}
> +
> +struct lruvec *lock_page_lruvec_irq(struct page *page)
> +{
> + struct lruvec *lruvec;
> + struct pglist_data *pgdat = page_pgdat(page);
> +
> + rcu_read_lock();
> + lruvec = mem_cgroup_page_lruvec(page, pgdat);
> + spin_lock_irq(&lruvec->lru_lock);
> + rcu_read_unlock();
> +
> + lruvec_memcg_debug(lruvec, page);
> +
> + return lruvec;
> +}
> +
> +struct lruvec *lock_page_lruvec_irqsave(struct page *page, unsigned long *flags)
> +{
> + struct lruvec *lruvec;
> + struct pglist_data *pgdat = page_pgdat(page);
> +
> + rcu_read_lock();
> + lruvec = mem_cgroup_page_lruvec(page, pgdat);
> + spin_lock_irqsave(&lruvec->lru_lock, *flags);
> + rcu_read_unlock();
> +
> + lruvec_memcg_debug(lruvec, page);
> +
> + return lruvec;
> +}
> +
> /**
> * mem_cgroup_update_lru_size - account for adding or removing an lru page
> * @lruvec: mem_cgroup per zone lru vector
> @@ -2999,7 +3058,7 @@ void __memcg_kmem_uncharge_page(struct page *page, int order)
>
> /*
> * Because tail pages are not marked as "used", set it. We're under
> - * pgdat->lru_lock and migration entries setup in all page mappings.
> + * lruvec->lru_lock and migration entries setup in all page mappings.
> */
> void mem_cgroup_split_huge_fixup(struct page *head)
> {
> diff --git a/mm/mlock.c b/mm/mlock.c
> index 0bdde88b4438..cb23a0c2cfbf 100644
> --- a/mm/mlock.c
> +++ b/mm/mlock.c
> @@ -163,7 +163,7 @@ unsigned int munlock_vma_page(struct page *page)
> {
> int nr_pages;
> bool clearlru = false;
> - pg_data_t *pgdat = page_pgdat(page);
> + struct lruvec *lruvec;
>
> /* For try_to_munlock() and to serialize with page migration */
> BUG_ON(!PageLocked(page));
> @@ -177,7 +177,7 @@ unsigned int munlock_vma_page(struct page *page)
> */
> get_page(page);
> clearlru = TestClearPageLRU(page);
> - spin_lock_irq(&pgdat->lru_lock);
> + lruvec = lock_page_lruvec_irq(page);
>
> if (!TestClearPageMlocked(page)) {
> if (clearlru)
> @@ -186,7 +186,7 @@ unsigned int munlock_vma_page(struct page *page)
> * Potentially, PTE-mapped THP: do not skip the rest PTEs
> * Reuse lock as memory barrier for release_pages racing.
> */
> - spin_unlock_irq(&pgdat->lru_lock);
> + unlock_page_lruvec_irq(lruvec);
> put_page(page);
> return 0;
> }
> @@ -195,14 +195,11 @@ unsigned int munlock_vma_page(struct page *page)
> __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
>
> if (clearlru) {
> - struct lruvec *lruvec;
> -
> - lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> del_page_from_lru_list(page, lruvec, page_lru(page));
> - spin_unlock_irq(&pgdat->lru_lock);
> + unlock_page_lruvec_irq(lruvec);
> __munlock_isolated_page(page);
> } else {
> - spin_unlock_irq(&pgdat->lru_lock);
> + unlock_page_lruvec_irq(lruvec);
> put_page(page);
> __munlock_isolation_failed(page);
> }
> @@ -284,6 +281,7 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
> int nr = pagevec_count(pvec);
> int delta_munlocked = -nr;
> struct pagevec pvec_putback;
> + struct lruvec *lruvec = NULL;
> int pgrescued = 0;
>
> pagevec_init(&pvec_putback);
> @@ -291,11 +289,17 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
> /* Phase 1: page isolation */
> for (i = 0; i < nr; i++) {
> struct page *page = pvec->pages[i];
> - struct lruvec *lruvec;
> + struct lruvec *new_lruvec;
> bool clearlru;
>
> clearlru = TestClearPageLRU(page);
> - spin_lock_irq(&zone->zone_pgdat->lru_lock);
> +
> + new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> + if (new_lruvec != lruvec) {
> + if (lruvec)
> + unlock_page_lruvec_irq(lruvec);
> + lruvec = lock_page_lruvec_irq(page);
> + }
So instead of trying to optimize things here you should go for parity.
If you are taking the old lru_lock once per pass you should do that
here too. You can come back through and optimize with the relock
approach later.
> if (!TestClearPageMlocked(page)) {
> delta_munlocked++;
> @@ -314,9 +318,7 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
> * We already have pin from follow_page_mask()
> * so we can spare the get_page() here.
> */
> - lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> del_page_from_lru_list(page, lruvec, page_lru(page));
> - spin_unlock_irq(&zone->zone_pgdat->lru_lock);
> continue;
>
> /*
> @@ -326,14 +328,12 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone)
> * the last pin, __page_cache_release() would deadlock.
> */
> putback:
> - spin_unlock_irq(&zone->zone_pgdat->lru_lock);
> pagevec_add(&pvec_putback, pvec->pages[i]);
> pvec->pages[i] = NULL;
> }
> - /* tempary disable irq, will remove later */
> - local_irq_disable();
> __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked);
> - local_irq_enable();
> + if (lruvec)
> + unlock_page_lruvec_irq(lruvec);
So I am not a fan of this change. You went to all the trouble of
reducing the lock scope just to bring it back out here again. In
addition it implies there is a path where you might try to update the
page state without disabling interrupts.
> /* Now we can release pins of pages that we are not munlocking */
> pagevec_release(&pvec_putback);
> diff --git a/mm/mmzone.c b/mm/mmzone.c
> index 4686fdc23bb9..3750a90ed4a0 100644
> --- a/mm/mmzone.c
> +++ b/mm/mmzone.c
> @@ -91,6 +91,7 @@ void lruvec_init(struct lruvec *lruvec)
> enum lru_list lru;
>
> memset(lruvec, 0, sizeof(struct lruvec));
> + spin_lock_init(&lruvec->lru_lock);
>
> for_each_lru(lru)
> INIT_LIST_HEAD(&lruvec->lists[lru]);
> diff --git a/mm/swap.c b/mm/swap.c
> index 8488b9b25730..129c532357a4 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -79,15 +79,13 @@ static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
> static void __page_cache_release(struct page *page)
> {
> if (PageLRU(page)) {
> - pg_data_t *pgdat = page_pgdat(page);
> struct lruvec *lruvec;
> unsigned long flags;
>
> __ClearPageLRU(page);
> - spin_lock_irqsave(&pgdat->lru_lock, flags);
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> + lruvec = lock_page_lruvec_irqsave(page, &flags);
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> }
> __ClearPageWaiters(page);
> }
> @@ -206,32 +204,30 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
> void (*move_fn)(struct page *page, struct lruvec *lruvec))
> {
> int i;
> - struct pglist_data *pgdat = NULL;
> - struct lruvec *lruvec;
> + struct lruvec *lruvec = NULL;
> unsigned long flags = 0;
>
> for (i = 0; i < pagevec_count(pvec); i++) {
> struct page *page = pvec->pages[i];
> - struct pglist_data *pagepgdat = page_pgdat(page);
> + struct lruvec *new_lruvec;
>
> - if (pagepgdat != pgdat) {
> - if (pgdat)
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> - pgdat = pagepgdat;
> - spin_lock_irqsave(&pgdat->lru_lock, flags);
> + new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> + if (lruvec != new_lruvec) {
> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> + lruvec = lock_page_lruvec_irqsave(page, &flags);
> }
>
> /* block memcg migration during page moving between lru */
> if (!TestClearPageLRU(page))
> continue;
>
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> (*move_fn)(page, lruvec);
>
> SetPageLRU(page);
> }
> - if (pgdat)
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> release_pages(pvec->pages, pvec->nr);
> pagevec_reinit(pvec);
> }
> @@ -274,9 +270,8 @@ void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
> {
> do {
> unsigned long lrusize;
> - struct pglist_data *pgdat = lruvec_pgdat(lruvec);
>
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
> /* Record cost event */
> if (file)
> lruvec->file_cost += nr_pages;
> @@ -300,7 +295,7 @@ void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
> lruvec->file_cost /= 2;
> lruvec->anon_cost /= 2;
> }
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
> } while ((lruvec = parent_lruvec(lruvec)));
> }
>
> @@ -365,11 +360,12 @@ static inline void activate_page_drain(int cpu)
> void activate_page(struct page *page)
> {
> pg_data_t *pgdat = page_pgdat(page);
> + struct lruvec *lruvec;
>
> page = compound_head(page);
> - spin_lock_irq(&pgdat->lru_lock);
> - __activate_page(page, mem_cgroup_page_lruvec(page, pgdat));
> - spin_unlock_irq(&pgdat->lru_lock);
> + lruvec = lock_page_lruvec_irq(page);
> + __activate_page(page, lruvec);
> + unlock_page_lruvec_irq(lruvec);
> }
> #endif
>
> @@ -819,8 +815,7 @@ void release_pages(struct page **pages, int nr)
> {
> int i;
> LIST_HEAD(pages_to_free);
> - struct pglist_data *locked_pgdat = NULL;
> - struct lruvec *lruvec;
> + struct lruvec *lruvec = NULL;
> unsigned long uninitialized_var(flags);
> unsigned int uninitialized_var(lock_batch);
>
> @@ -830,21 +825,20 @@ void release_pages(struct page **pages, int nr)
> /*
> * Make sure the IRQ-safe lock-holding time does not get
> * excessive with a continuous string of pages from the
> - * same pgdat. The lock is held only if pgdat != NULL.
> + * same lruvec. The lock is held only if lruvec != NULL.
> */
> - if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
> - spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
> - locked_pgdat = NULL;
> + if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> + lruvec = NULL;
> }
>
> if (is_huge_zero_page(page))
> continue;
>
> if (is_zone_device_page(page)) {
> - if (locked_pgdat) {
> - spin_unlock_irqrestore(&locked_pgdat->lru_lock,
> - flags);
> - locked_pgdat = NULL;
> + if (lruvec) {
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> + lruvec = NULL;
> }
> /*
> * ZONE_DEVICE pages that return 'false' from
> @@ -863,28 +857,28 @@ void release_pages(struct page **pages, int nr)
> continue;
>
> if (PageCompound(page)) {
> - if (locked_pgdat) {
> - spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
> - locked_pgdat = NULL;
> + if (lruvec) {
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> + lruvec = NULL;
> }
> __put_compound_page(page);
> continue;
> }
>
> if (PageLRU(page)) {
> - struct pglist_data *pgdat = page_pgdat(page);
> + struct lruvec *new_lruvec;
>
> - if (pgdat != locked_pgdat) {
> - if (locked_pgdat)
> - spin_unlock_irqrestore(&locked_pgdat->lru_lock,
> + new_lruvec = mem_cgroup_page_lruvec(page,
> + page_pgdat(page));
> + if (new_lruvec != lruvec) {
> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec,
> flags);
> lock_batch = 0;
> - locked_pgdat = pgdat;
> - spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
> + lruvec = lock_page_lruvec_irqsave(page, &flags);
> }
This just kind of seems ugly to me. I am not a fan of having to fetch
the lruvec twice when you already have it in new_lruvec. I suppose it
is fine though since you are just going to be replacing it later
anyway.
>
> __ClearPageLRU(page);
> - lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
> }
>
> @@ -894,8 +888,8 @@ void release_pages(struct page **pages, int nr)
>
> list_add(&page->lru, &pages_to_free);
> }
> - if (locked_pgdat)
> - spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec, flags);
>
> mem_cgroup_uncharge_list(&pages_to_free);
> free_unref_page_list(&pages_to_free);
> @@ -983,26 +977,24 @@ static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec)
> void __pagevec_lru_add(struct pagevec *pvec)
> {
> int i;
> - struct pglist_data *pgdat = NULL;
> - struct lruvec *lruvec;
> + struct lruvec *lruvec = NULL;
> unsigned long flags = 0;
>
> for (i = 0; i < pagevec_count(pvec); i++) {
> struct page *page = pvec->pages[i];
> - struct pglist_data *pagepgdat = page_pgdat(page);
> + struct lruvec *new_lruvec;
>
> - if (pagepgdat != pgdat) {
> - if (pgdat)
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> - pgdat = pagepgdat;
> - spin_lock_irqsave(&pgdat->lru_lock, flags);
> + new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> + if (lruvec != new_lruvec) {
> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> + lruvec = lock_page_lruvec_irqsave(page, &flags);
> }
>
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> __pagevec_lru_add_fn(page, lruvec);
> }
> - if (pgdat)
> - spin_unlock_irqrestore(&pgdat->lru_lock, flags);
> + if (lruvec)
> + unlock_page_lruvec_irqrestore(lruvec, flags);
> release_pages(pvec->pages, pvec->nr);
> pagevec_reinit(pvec);
> }
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index f77748adc340..168c1659e430 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1774,15 +1774,13 @@ int isolate_lru_page(struct page *page)
> WARN_RATELIMIT(PageTail(page), "trying to isolate tail page");
>
> if (TestClearPageLRU(page)) {
> - pg_data_t *pgdat = page_pgdat(page);
> struct lruvec *lruvec;
> int lru = page_lru(page);
>
> get_page(page);
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> - spin_lock_irq(&pgdat->lru_lock);
> + lruvec = lock_page_lruvec_irq(page);
> del_page_from_lru_list(page, lruvec, lru);
> - spin_unlock_irq(&pgdat->lru_lock);
> + unlock_page_lruvec_irq(lruvec);
> ret = 0;
> }
>
> @@ -1849,20 +1847,22 @@ static int too_many_isolated(struct pglist_data *pgdat, int file,
> static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
> struct list_head *list)
> {
> - struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> int nr_pages, nr_moved = 0;
> LIST_HEAD(pages_to_free);
> struct page *page;
> + struct lruvec *orig_lruvec = lruvec;
> enum lru_list lru;
>
> while (!list_empty(list)) {
> + struct lruvec *new_lruvec = NULL;
> +
> page = lru_to_page(list);
> VM_BUG_ON_PAGE(PageLRU(page), page);
> list_del(&page->lru);
> if (unlikely(!page_evictable(page))) {
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
> putback_lru_page(page);
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
> continue;
> }
>
> @@ -1876,6 +1876,12 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
> * list_add(&page->lru,)
> * list_add(&page->lru,) //corrupt
> */
> + new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> + if (new_lruvec != lruvec) {
> + if (lruvec)
> + spin_unlock_irq(&lruvec->lru_lock);
> + lruvec = lock_page_lruvec_irq(page);
> + }
> SetPageLRU(page);
>
> if (unlikely(put_page_testzero(page))) {
> @@ -1883,16 +1889,15 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
> __ClearPageActive(page);
>
> if (unlikely(PageCompound(page))) {
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
> destroy_compound_page(page);
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
> } else
> list_add(&page->lru, &pages_to_free);
>
> continue;
> }
>
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
> lru = page_lru(page);
> nr_pages = hpage_nr_pages(page);
>
> @@ -1902,6 +1907,11 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec,
> if (PageActive(page))
> workingset_age_nonresident(lruvec, nr_pages);
> }
> + if (orig_lruvec != lruvec) {
> + if (lruvec)
> + spin_unlock_irq(&lruvec->lru_lock);
> + spin_lock_irq(&orig_lruvec->lru_lock);
> + }
>
> /*
> * To save our caller's stack, now use input list for pages to free.
Something like this seems much more readable than the block you had
above. It is what I would expect the relock code to look like.
> @@ -1957,7 +1967,7 @@ static int current_may_throttle(void)
>
> lru_add_drain();
>
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
>
> nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &page_list,
> &nr_scanned, sc, lru);
> @@ -1969,7 +1979,7 @@ static int current_may_throttle(void)
> __count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned);
> __count_vm_events(PGSCAN_ANON + file, nr_scanned);
>
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
>
> if (nr_taken == 0)
> return 0;
> @@ -1977,7 +1987,7 @@ static int current_may_throttle(void)
> nr_reclaimed = shrink_page_list(&page_list, pgdat, sc, 0,
> &stat, false);
>
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
> move_pages_to_lru(lruvec, &page_list);
>
> __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
> @@ -1986,7 +1996,7 @@ static int current_may_throttle(void)
> __count_vm_events(item, nr_reclaimed);
> __count_memcg_events(lruvec_memcg(lruvec), item, nr_reclaimed);
> __count_vm_events(PGSTEAL_ANON + file, nr_reclaimed);
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
>
> lru_note_cost(lruvec, file, stat.nr_pageout);
> mem_cgroup_uncharge_list(&page_list);
> @@ -2039,7 +2049,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>
> lru_add_drain();
>
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
>
> nr_taken = isolate_lru_pages(nr_to_scan, lruvec, &l_hold,
> &nr_scanned, sc, lru);
> @@ -2049,7 +2059,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
> __count_vm_events(PGREFILL, nr_scanned);
> __count_memcg_events(lruvec_memcg(lruvec), PGREFILL, nr_scanned);
>
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
>
> while (!list_empty(&l_hold)) {
> cond_resched();
> @@ -2095,7 +2105,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
> /*
> * Move pages back to the lru list.
> */
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&lruvec->lru_lock);
>
> nr_activate = move_pages_to_lru(lruvec, &l_active);
> nr_deactivate = move_pages_to_lru(lruvec, &l_inactive);
> @@ -2106,7 +2116,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
> __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, nr_deactivate);
>
> __mod_node_page_state(pgdat, NR_ISOLATED_ANON + file, -nr_taken);
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&lruvec->lru_lock);
>
> mem_cgroup_uncharge_list(&l_active);
> free_unref_page_list(&l_active);
> @@ -2696,10 +2706,10 @@ static void shrink_node(pg_data_t *pgdat, struct scan_control *sc)
> /*
> * Determine the scan balance between anon and file LRUs.
> */
> - spin_lock_irq(&pgdat->lru_lock);
> + spin_lock_irq(&target_lruvec->lru_lock);
> sc->anon_cost = target_lruvec->anon_cost;
> sc->file_cost = target_lruvec->file_cost;
> - spin_unlock_irq(&pgdat->lru_lock);
> + spin_unlock_irq(&target_lruvec->lru_lock);
>
> /*
> * Target desirable inactive:active list ratios for the anon
> @@ -4275,24 +4285,22 @@ int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
> */
> void check_move_unevictable_pages(struct pagevec *pvec)
> {
> - struct lruvec *lruvec;
> - struct pglist_data *pgdat = NULL;
> + struct lruvec *lruvec = NULL;
> int pgscanned = 0;
> int pgrescued = 0;
> int i;
>
> for (i = 0; i < pvec->nr; i++) {
> struct page *page = pvec->pages[i];
> - struct pglist_data *pagepgdat = page_pgdat(page);
> + struct lruvec *new_lruvec;
>
> pgscanned++;
> - if (pagepgdat != pgdat) {
> - if (pgdat)
> - spin_unlock_irq(&pgdat->lru_lock);
> - pgdat = pagepgdat;
> - spin_lock_irq(&pgdat->lru_lock);
> + new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page));
> + if (lruvec != new_lruvec) {
> + if (lruvec)
> + unlock_page_lruvec_irq(lruvec);
> + lruvec = lock_page_lruvec_irq(page);
> }
> - lruvec = mem_cgroup_page_lruvec(page, pgdat);
>
> if (!PageLRU(page) || !PageUnevictable(page))
> continue;
> @@ -4308,10 +4316,10 @@ void check_move_unevictable_pages(struct pagevec *pvec)
> }
> }
>
> - if (pgdat) {
> + if (lruvec) {
> __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
> __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
> - spin_unlock_irq(&pgdat->lru_lock);
> + unlock_page_lruvec_irq(lruvec);
> }
> }
> EXPORT_SYMBOL_GPL(check_move_unevictable_pages);
> --
> 1.8.3.1
>
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