| Message ID | 1573874106-23802-4-git-send-email-alex.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | per lruvec lru_lock for memcg | expand |
On Sat, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: > This is the main patch to replace per node lru_lock with per memcg > lruvec lock. It also fold the irqsave flags into lruvec. I have to say, I don't love the part where we fold the irqsave flags into the lruvec. I know it saves us an argument, but it opens up the possibility of mismatched expectations. eg we currently have: static void __split_huge_page(struct page *page, struct list_head *list, struct lruvec *lruvec, pgoff_t end) { ... spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); so if we introduce a new caller, we have to be certain that this caller is also using lock_page_lruvec_irqsave() and not lock_page_lruvec_irq(). I can't think of a way to make the compiler enforce that, and if we don't, then we can get some odd crashes with interrupts being unexpectedly enabled or disabled, depending on how ->irqflags was used last. So it makes the code more subtle. And that's not a good thing. > +static inline struct lruvec *lock_page_lruvec_irq(struct page *page, > + struct pglist_data *pgdat) > +{ > + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); > + > + spin_lock_irq(&lruvec->lru_lock); > + > + return lruvec; > +} ... > +static struct lruvec *lock_page_lru(struct page *page, int *isolated) > { > pg_data_t *pgdat = page_pgdat(page); > + struct lruvec *lruvec = lock_page_lruvec_irq(page, pgdat); > > - spin_lock_irq(&pgdat->lru_lock); > 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; > } else > *isolated = 0; > + > + return lruvec; > } But what if the page is !PageLRU? What lruvec did we just lock? According to the comments on mem_cgroup_page_lruvec(), * This function is only safe when following the LRU page isolation * and putback protocol: the LRU lock must be held, and the page must * either be PageLRU() or the caller must have isolated/allocated it. and now it's being called in order to find out which LRU lock to take. So this comment needs to be updated, if it's wrong, or this patch has a race.
On Fri, Nov 15, 2019 at 7:15 PM Alex Shi <alex.shi@linux.alibaba.com> wrote: > > This patchset move lru_lock into lruvec, give a lru_lock for each of > lruvec, thus bring a lru_lock for each of memcg per node. > > This is the main patch to replace per node lru_lock with per memcg > lruvec lock. It also fold the irqsave flags into lruvec. > > We introduce function lock_page_lruvec, it's same as vanilla pgdat lock > when memory cgroup unset, w/o memcg, the function will keep repin the > lruvec's lock to guard from page->mem_cgroup changes in page > migrations between memcgs. (Thanks Hugh Dickins and Konstantin > Khlebnikov reminder on this. Than the core logical is same as their > previous patchs) > > According to Daniel Jordan's suggestion, I run 64 'dd' with on 32 > containers on my 2s* 8 core * HT box with the 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 dd performance is 144MB/s, the vanilla > kernel performance is 123MB/s. 17% performance increased. > > Signed-off-by: Alex Shi <alex.shi@linux.alibaba.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: Roman Gushchin <guro@fb.com> > Cc: Shakeel Butt <shakeelb@google.com> > Cc: Chris Down <chris@chrisdown.name> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Qian Cai <cai@lca.pw> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> > Cc: "Jérôme Glisse" <jglisse@redhat.com> > Cc: Andrea Arcangeli <aarcange@redhat.com> > Cc: Yang Shi <yang.shi@linux.alibaba.com> > Cc: David Rientjes <rientjes@google.com> > Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> > Cc: swkhack <swkhack@gmail.com> > Cc: "Potyra, Stefan" <Stefan.Potyra@elektrobit.com> > Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> > Cc: Stephen Rothwell <sfr@canb.auug.org.au> > Cc: Colin Ian King <colin.king@canonical.com> > Cc: Jason Gunthorpe <jgg@ziepe.ca> > Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Peng Fan <peng.fan@nxp.com> > Cc: Nikolay Borisov <nborisov@suse.com> > Cc: Ira Weiny <ira.weiny@intel.com> > Cc: Kirill Tkhai <ktkhai@virtuozzo.com> > Cc: Yafang Shao <laoar.shao@gmail.com> > Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> > Cc: Hugh Dickins <hughd@google.com> > Cc: Tejun Heo <tj@kernel.org> > Cc: linux-kernel@vger.kernel.org > Cc: linux-mm@kvack.org > Cc: cgroups@vger.kernel.org > --- > include/linux/memcontrol.h | 23 ++++++++++++++ > mm/compaction.c | 62 ++++++++++++++++++++++++------------ > mm/huge_memory.c | 16 ++++------ > mm/memcontrol.c | 64 +++++++++++++++++++++++++++++-------- > mm/mlock.c | 31 +++++++++--------- > mm/page_idle.c | 5 +-- > mm/swap.c | 79 +++++++++++++++++++--------------------------- > mm/vmscan.c | 58 ++++++++++++++++------------------ > 8 files changed, 201 insertions(+), 137 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index 5b86287fa069..0b32eadd0eda 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -418,6 +418,9 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg, > > struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *); > > +struct lruvec *lock_page_lruvec_irq(struct page *, struct pglist_data *); > +struct lruvec *lock_page_lruvec_irqsave(struct page *, struct pglist_data *); > + > struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); > > struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm); > @@ -901,6 +904,26 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page, > return &pgdat->__lruvec; > } > > +static inline struct lruvec *lock_page_lruvec_irq(struct page *page, > + struct pglist_data *pgdat) > +{ > + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); > + > + spin_lock_irq(&lruvec->lru_lock); > + > + return lruvec; > +} > + > +static inline struct lruvec *lock_page_lruvec_irqsave(struct page *page, > + struct pglist_data *pgdat) > +{ > + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); > + > + spin_lock_irqsave(&lruvec->lru_lock, lruvec->irqflags); > + > + return lruvec; > +} > + > static inline bool mm_match_cgroup(struct mm_struct *mm, > struct mem_cgroup *memcg) > { > diff --git a/mm/compaction.c b/mm/compaction.c > index d20816b21b55..eb1ad30c1bef 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -786,8 +786,7 @@ static bool too_many_isolated(pg_data_t *pgdat) > pg_data_t *pgdat = cc->zone->zone_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 +846,21 @@ 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) { > + spin_unlock_irqrestore(&locked_lruvec->lru_lock, > + locked_lruvec->irqflags); > + 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)) > @@ -920,10 +929,10 @@ 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) { > + spin_unlock_irqrestore(&locked_lruvec->lru_lock, > + locked_lruvec->irqflags); > + locked_lruvec = NULL; > } > > if (!isolate_movable_page(page, isolate_mode)) > @@ -949,10 +958,22 @@ static bool too_many_isolated(pg_data_t *pgdat) > if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page)) > goto isolate_fail; > > +reget_lruvec: > + 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) { > + spin_unlock_irqrestore(&locked_lruvec->lru_lock, > + locked_lruvec->irqflags); > + locked_lruvec = NULL; > + } What guarantees the lifetime of lruvec? You should read the comment on mem_cgroup_page_lruvec(). Have you seen the patches Hugh had shared? Please look at the trylock_page_lruvec(). BTW have you tested Hugh's patches? > + if (compact_lock_irqsave(&lruvec->lru_lock, > + &lruvec->irqflags, cc)) > + locked_lruvec = lruvec; > + > + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) > + goto reget_lruvec; > > /* Try get exclusive access under lock */ > if (!skip_updated) { > @@ -976,7 +997,6 @@ static bool too_many_isolated(pg_data_t *pgdat) > } > } > > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > > /* Try isolate the page */ > if (__isolate_lru_page(page, isolate_mode) != 0) > @@ -1017,9 +1037,10 @@ 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) { > + spin_unlock_irqrestore(&locked_lruvec->lru_lock, > + locked_lruvec->irqflags); > + locked_lruvec = NULL; > } > putback_movable_pages(&cc->migratepages); > cc->nr_migratepages = 0; > @@ -1044,8 +1065,9 @@ static bool too_many_isolated(pg_data_t *pgdat) > low_pfn = end_pfn; > > isolate_abort: > - if (locked) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > + if (locked_lruvec) > + spin_unlock_irqrestore(&locked_lruvec->lru_lock, > + locked_lruvec->irqflags); > > /* > * Updated the cached scanner pfn once the pageblock has been scanned > diff --git a/mm/huge_memory.c b/mm/huge_memory.c > index 13cc93785006..7e8bd6c700d2 100644 > --- a/mm/huge_memory.c > +++ b/mm/huge_memory.c > @@ -2495,17 +2495,13 @@ static void __split_huge_page_tail(struct page *head, int tail, > } > > static void __split_huge_page(struct page *page, struct list_head *list, > - pgoff_t end, unsigned long flags) > + struct lruvec *lruvec, 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; > int i; > > - lruvec = mem_cgroup_page_lruvec(head, pgdat); > - > /* complete memcg works before add pages to LRU */ > mem_cgroup_split_huge_fixup(head); > > @@ -2554,7 +2550,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, > xa_unlock(&head->mapping->i_pages); > } > > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > > remap_page(head); > > @@ -2697,9 +2693,9 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > struct deferred_split *ds_queue = get_deferred_split_queue(page); > struct anon_vma *anon_vma = NULL; > struct address_space *mapping = NULL; > + struct lruvec *lruvec; > int count, mapcount, extra_pins, ret; > bool mlocked; > - unsigned long flags; > pgoff_t end; > > VM_BUG_ON_PAGE(is_huge_zero_page(page), page); > @@ -2766,7 +2762,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > lru_add_drain(); > > /* prevent PageLRU to go away from under us, and freeze lru stats */ > - spin_lock_irqsave(&pgdata->lru_lock, flags); > + lruvec = lock_page_lruvec_irqsave(head, pgdata); > > if (mapping) { > XA_STATE(xas, &mapping->i_pages, page_index(head)); > @@ -2797,7 +2793,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > } > > spin_unlock(&ds_queue->split_queue_lock); > - __split_huge_page(page, list, end, flags); > + __split_huge_page(page, list, lruvec, end); > if (PageSwapCache(head)) { > swp_entry_t entry = { .val = page_private(head) }; > > @@ -2816,7 +2812,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) > spin_unlock(&ds_queue->split_queue_lock); > fail: if (mapping) > xa_unlock(&mapping->i_pages); > - spin_unlock_irqrestore(&pgdata->lru_lock, flags); > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > remap_page(head); > ret = -EBUSY; > } > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 62470325f9bc..cf274739e619 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1246,6 +1246,42 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd > return lruvec; > } > > +struct lruvec *lock_page_lruvec_irq(struct page *page, > + struct pglist_data *pgdat) > +{ > + struct lruvec *lruvec; > + > +again: > + lruvec = mem_cgroup_page_lruvec(page, pgdat); > + spin_lock_irq(&lruvec->lru_lock); > + > + /* lruvec may changed in commit_charge() */ > + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) { > + spin_unlock_irq(&lruvec->lru_lock); > + goto again; > + } > + > + return lruvec; > +} > + > +struct lruvec *lock_page_lruvec_irqsave(struct page *page, > + struct pglist_data *pgdat) > +{ > + struct lruvec *lruvec; > + > +again: > + lruvec = mem_cgroup_page_lruvec(page, pgdat); > + spin_lock_irqsave(&lruvec->lru_lock, lruvec->irqflags); > + > + /* lruvec may changed in commit_charge() */ > + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) { > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > + goto again; > + } > + > + return lruvec; > +} > + > /** > * mem_cgroup_update_lru_size - account for adding or removing an lru page > * @lruvec: mem_cgroup per zone lru vector > @@ -2571,41 +2607,43 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) > css_put_many(&memcg->css, nr_pages); > } > > -static void lock_page_lru(struct page *page, int *isolated) > +static struct lruvec *lock_page_lru(struct page *page, int *isolated) > { > pg_data_t *pgdat = page_pgdat(page); > + struct lruvec *lruvec = lock_page_lruvec_irq(page, pgdat); > > - spin_lock_irq(&pgdat->lru_lock); > 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; > } else > *isolated = 0; > + > + return lruvec; > } > > -static void unlock_page_lru(struct page *page, int isolated) > +static void unlock_page_lru(struct page *page, int isolated, > + struct lruvec *locked_lruvec) > { > - pg_data_t *pgdat = page_pgdat(page); > + struct lruvec *lruvec; > > - if (isolated) { > - struct lruvec *lruvec; > + spin_unlock_irq(&locked_lruvec->lru_lock); > + lruvec = lock_page_lruvec_irq(page, page_pgdat(page)); > > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > + if (isolated) { > VM_BUG_ON_PAGE(PageLRU(page), page); > SetPageLRU(page); > add_page_to_lru_list(page, lruvec, page_lru(page)); > } > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > } > > static void commit_charge(struct page *page, struct mem_cgroup *memcg, > bool lrucare) > { > int isolated; > + struct lruvec *lruvec; > > VM_BUG_ON_PAGE(page->mem_cgroup, page); > > @@ -2614,7 +2652,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg, > * may already be on some other mem_cgroup's LRU. Take care of it. > */ > if (lrucare) > - lock_page_lru(page, &isolated); > + lruvec = lock_page_lru(page, &isolated); > > /* > * Nobody should be changing or seriously looking at > @@ -2633,7 +2671,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg, > page->mem_cgroup = memcg; > > if (lrucare) > - unlock_page_lru(page, isolated); > + unlock_page_lru(page, isolated, lruvec); > } > > #ifdef CONFIG_MEMCG_KMEM > @@ -2929,7 +2967,7 @@ void __memcg_kmem_uncharge(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. > + * pgdat->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 a72c1eeded77..b509b80b8513 100644 > --- a/mm/mlock.c > +++ b/mm/mlock.c > @@ -106,12 +106,10 @@ void mlock_vma_page(struct page *page) > * Isolate a page from LRU with optional get_page() pin. > * Assumes lru_lock already held and page already pinned. > */ > -static bool __munlock_isolate_lru_page(struct page *page, bool getpage) > +static bool __munlock_isolate_lru_page(struct page *page, > + struct lruvec *lruvec, bool getpage) > { > if (PageLRU(page)) { > - struct lruvec *lruvec; > - > - lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); > if (getpage) > get_page(page); > ClearPageLRU(page); > @@ -183,6 +181,7 @@ unsigned int munlock_vma_page(struct page *page) > { > int nr_pages; > pg_data_t *pgdat = page_pgdat(page); > + struct lruvec *lruvec; > > /* For try_to_munlock() and to serialize with page migration */ > BUG_ON(!PageLocked(page)); > @@ -194,7 +193,7 @@ unsigned int munlock_vma_page(struct page *page) > * might otherwise copy PageMlocked to part of the tail pages before > * we clear it in the head page. It also stabilizes hpage_nr_pages(). > */ > - spin_lock_irq(&pgdat->lru_lock); > + lruvec = lock_page_lruvec_irq(page, pgdat); > > if (!TestClearPageMlocked(page)) { > /* Potentially, PTE-mapped THP: do not skip the rest PTEs */ > @@ -205,15 +204,15 @@ unsigned int munlock_vma_page(struct page *page) > nr_pages = hpage_nr_pages(page); > __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); > > - if (__munlock_isolate_lru_page(page, true)) { > - spin_unlock_irq(&pgdat->lru_lock); > + if (__munlock_isolate_lru_page(page, lruvec, true)) { > + spin_unlock_irq(&lruvec->lru_lock); > __munlock_isolated_page(page); > goto out; > } > __munlock_isolation_failed(page); > > unlock_out: > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > > out: > return nr_pages - 1; > @@ -291,28 +290,29 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) > { > int i; > int nr = pagevec_count(pvec); > - int delta_munlocked = -nr; > struct pagevec pvec_putback; > + struct lruvec *lruvec = NULL; > int pgrescued = 0; > > pagevec_init(&pvec_putback); > > /* Phase 1: page isolation */ > - spin_lock_irq(&zone->zone_pgdat->lru_lock); > for (i = 0; i < nr; i++) { > struct page *page = pvec->pages[i]; > > + lruvec = lock_page_lruvec_irq(page, page_pgdat(page)); > + > if (TestClearPageMlocked(page)) { > /* > * We already have pin from follow_page_mask() > * so we can spare the get_page() here. > */ > - if (__munlock_isolate_lru_page(page, false)) > + if (__munlock_isolate_lru_page(page, lruvec, false)) { > + __mod_zone_page_state(zone, NR_MLOCK, -1); > + spin_unlock_irq(&lruvec->lru_lock); > continue; > - else > + } else > __munlock_isolation_failed(page); > - } else { > - delta_munlocked++; > } > > /* > @@ -323,9 +323,8 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) > */ > pagevec_add(&pvec_putback, pvec->pages[i]); > pvec->pages[i] = NULL; > + spin_unlock_irq(&lruvec->lru_lock); > } > - __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); > - spin_unlock_irq(&zone->zone_pgdat->lru_lock); > > /* Now we can release pins of pages that we are not munlocking */ > pagevec_release(&pvec_putback); > diff --git a/mm/page_idle.c b/mm/page_idle.c > index 295512465065..25f4b1cf3e0f 100644 > --- a/mm/page_idle.c > +++ b/mm/page_idle.c > @@ -32,6 +32,7 @@ static struct page *page_idle_get_page(unsigned long pfn) > { > struct page *page; > pg_data_t *pgdat; > + struct lruvec *lruvec; > > if (!pfn_valid(pfn)) > return NULL; > @@ -42,12 +43,12 @@ static struct page *page_idle_get_page(unsigned long pfn) > return NULL; > > pgdat = page_pgdat(page); > - spin_lock_irq(&pgdat->lru_lock); > + lruvec = lock_page_lruvec_irq(page, pgdat); > if (unlikely(!PageLRU(page))) { > put_page(page); > page = NULL; > } > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > return page; > } > > diff --git a/mm/swap.c b/mm/swap.c > index 5341ae93861f..60f04cb2b49e 100644 > --- a/mm/swap.c > +++ b/mm/swap.c > @@ -62,14 +62,12 @@ static void __page_cache_release(struct page *page) > if (PageLRU(page)) { > pg_data_t *pgdat = page_pgdat(page); > struct lruvec *lruvec; > - unsigned long flags; > > - spin_lock_irqsave(&pgdat->lru_lock, flags); > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > + lruvec = lock_page_lruvec_irqsave(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); > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > } > __ClearPageWaiters(page); > } > @@ -192,26 +190,17 @@ static void pagevec_lru_move_fn(struct pagevec *pvec, > void *arg) > { > int i; > - struct pglist_data *pgdat = NULL; > - struct lruvec *lruvec; > - unsigned long flags = 0; > + struct lruvec *lruvec = NULL; > > for (i = 0; i < pagevec_count(pvec); i++) { > struct page *page = pvec->pages[i]; > - struct pglist_data *pagepgdat = page_pgdat(page); > > - if (pagepgdat != pgdat) { > - if (pgdat) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > - pgdat = pagepgdat; > - spin_lock_irqsave(&pgdat->lru_lock, flags); > - } > + lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page)); > > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > (*move_fn)(page, lruvec, arg); > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > } > - if (pgdat) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > + > release_pages(pvec->pages, pvec->nr); > pagevec_reinit(pvec); > } > @@ -325,11 +314,12 @@ 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), NULL); > - spin_unlock_irq(&pgdat->lru_lock); > + lruvec = lock_page_lruvec_irq(page, pgdat); > + __activate_page(page, lruvec, NULL); > + spin_unlock_irq(&lruvec->lru_lock); > } > #endif > > @@ -780,9 +770,7 @@ void release_pages(struct page **pages, int nr) > { > int i; > LIST_HEAD(pages_to_free); > - struct pglist_data *locked_pgdat = NULL; > - struct lruvec *lruvec; > - unsigned long uninitialized_var(flags); > + struct lruvec *lruvec = NULL; > unsigned int uninitialized_var(lock_batch); > > for (i = 0; i < nr; i++) { > @@ -791,21 +779,22 @@ 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) { > + spin_unlock_irqrestore(&lruvec->lru_lock, > + lruvec->irqflags); > + 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) { > + spin_unlock_irqrestore(&lruvec->lru_lock, > + lruvec->irqflags); > + lruvec = NULL; > } > /* > * ZONE_DEVICE pages that return 'false' from > @@ -822,27 +811,25 @@ 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) { > + spin_unlock_irqrestore(&lruvec->lru_lock, > + lruvec->irqflags); > + lruvec = NULL; > } > __put_compound_page(page); > continue; > } > > if (PageLRU(page)) { > - struct pglist_data *pgdat = page_pgdat(page); > + struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); > > - if (pgdat != locked_pgdat) { > - if (locked_pgdat) > - spin_unlock_irqrestore(&locked_pgdat->lru_lock, > - flags); > + if (new_lruvec != lruvec) { > + if (lruvec) > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > lock_batch = 0; > - locked_pgdat = pgdat; > - spin_lock_irqsave(&locked_pgdat->lru_lock, flags); > - } > + lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page)); > > - lruvec = mem_cgroup_page_lruvec(page, locked_pgdat); > + } > VM_BUG_ON_PAGE(!PageLRU(page), page); > __ClearPageLRU(page); > del_page_from_lru_list(page, lruvec, page_off_lru(page)); > @@ -854,8 +841,8 @@ 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) > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > > mem_cgroup_uncharge_list(&pages_to_free); > free_unref_page_list(&pages_to_free); > @@ -893,7 +880,7 @@ void lru_add_page_tail(struct page *page, struct page *page_tail, > VM_BUG_ON_PAGE(!PageHead(page), page); > VM_BUG_ON_PAGE(PageCompound(page_tail), page); > VM_BUG_ON_PAGE(PageLRU(page_tail), page); > - lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); > + lockdep_assert_held(&lruvec->lru_lock); > > if (!list) > SetPageLRU(page_tail); > diff --git a/mm/vmscan.c b/mm/vmscan.c > index d97985262dda..3cdf343e7a27 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1755,8 +1755,7 @@ int isolate_lru_page(struct page *page) > pg_data_t *pgdat = page_pgdat(page); > struct lruvec *lruvec; > > - spin_lock_irq(&pgdat->lru_lock); > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > + lruvec = lock_page_lruvec_irq(page, pgdat); > if (PageLRU(page)) { > int lru = page_lru(page); > get_page(page); > @@ -1764,7 +1763,7 @@ int isolate_lru_page(struct page *page) > del_page_from_lru_list(page, lruvec, lru); > ret = 0; > } > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > } > return ret; > } > @@ -1829,7 +1828,6 @@ 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; > @@ -1840,12 +1838,11 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, > VM_BUG_ON_PAGE(PageLRU(page), page); > if (unlikely(!page_evictable(page))) { > list_del(&page->lru); > - 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; > } > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > > SetPageLRU(page); > lru = page_lru(page); > @@ -1860,9 +1857,9 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, > del_page_from_lru_list(page, lruvec, lru); > > if (unlikely(PageCompound(page))) { > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > (*get_compound_page_dtor(page))(page); > - spin_lock_irq(&pgdat->lru_lock); > + spin_lock_irq(&lruvec->lru_lock); > } else > list_add(&page->lru, &pages_to_free); > } else { > @@ -1925,7 +1922,7 @@ 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); > @@ -1937,7 +1934,7 @@ static int current_may_throttle(void) > if (!cgroup_reclaim(sc)) > __count_vm_events(item, nr_scanned); > __count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned); > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > > if (nr_taken == 0) > return 0; > @@ -1945,7 +1942,7 @@ 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); > > item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT; > if (!cgroup_reclaim(sc)) > @@ -1958,7 +1955,7 @@ static int current_may_throttle(void) > > __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(&page_list); > free_unref_page_list(&page_list); > @@ -2011,7 +2008,7 @@ 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); > @@ -2022,7 +2019,7 @@ 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(); > @@ -2068,7 +2065,7 @@ 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); > /* > * Count referenced pages from currently used mappings as rotated, > * even though only some of them are actually re-activated. This > @@ -2086,7 +2083,7 @@ 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); > @@ -2371,7 +2368,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, > file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + > lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); > > - spin_lock_irq(&pgdat->lru_lock); > + spin_lock_irq(&lruvec->lru_lock); > if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { > reclaim_stat->recent_scanned[0] /= 2; > reclaim_stat->recent_rotated[0] /= 2; > @@ -2392,7 +2389,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, > > fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); > fp /= reclaim_stat->recent_rotated[1] + 1; > - spin_unlock_irq(&pgdat->lru_lock); > + spin_unlock_irq(&lruvec->lru_lock); > > fraction[0] = ap; > fraction[1] = fp; > @@ -4285,24 +4282,25 @@ int page_evictable(struct page *page) > */ > 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 pglist_data *pgdat = page_pgdat(page); > + struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, pgdat); > + > > pgscanned++; > - if (pagepgdat != pgdat) { > - if (pgdat) > - spin_unlock_irq(&pgdat->lru_lock); > - pgdat = pagepgdat; > - spin_lock_irq(&pgdat->lru_lock); > + > + if (lruvec != new_lruvec) { > + if (lruvec) > + spin_unlock_irq(&lruvec->lru_lock); > + lruvec = new_lruvec; > + spin_lock_irq(&lruvec->lru_lock); > } > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > > if (!PageLRU(page) || !PageUnevictable(page)) > continue; > @@ -4318,10 +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); > + spin_unlock_irq(&lruvec->lru_lock); > } > } > EXPORT_SYMBOL_GPL(check_move_unevictable_pages); > -- > 1.8.3.1 >
在 2019/11/16 下午12:38, Matthew Wilcox 写道: > On Sat, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: >> This is the main patch to replace per node lru_lock with per memcg >> lruvec lock. It also fold the irqsave flags into lruvec. > > I have to say, I don't love the part where we fold the irqsave flags > into the lruvec. I know it saves us an argument, but it opens up the > possibility of mismatched expectations. eg we currently have: > > static void __split_huge_page(struct page *page, struct list_head *list, > struct lruvec *lruvec, pgoff_t end) > { > ... > spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > > so if we introduce a new caller, we have to be certain that this caller > is also using lock_page_lruvec_irqsave() and not lock_page_lruvec_irq(). > I can't think of a way to make the compiler enforce that, and if we don't, > then we can get some odd crashes with interrupts being unexpectedly > enabled or disabled, depending on how ->irqflags was used last. > > So it makes the code more subtle. And that's not a good thing. Hi Matthew, Thanks for comments! Here, the irqflags is bound, and belong to lruvec, merging them into together helps us to take them as whole, and thus reduce a unnecessary code clues. The only thing maybe bad that it may take move place in pg_data_t.lruvec, but there are PADDINGs to remove this concern. As your concern for a 'new' caller, since __split_huge_page is a static helper here, no distub for anyothers. Do you agree on that? > >> +static inline struct lruvec *lock_page_lruvec_irq(struct page *page, >> + struct pglist_data *pgdat) >> +{ >> + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); >> + >> + spin_lock_irq(&lruvec->lru_lock); >> + >> + return lruvec; >> +} > > ... > >> +static struct lruvec *lock_page_lru(struct page *page, int *isolated) >> { >> pg_data_t *pgdat = page_pgdat(page); >> + struct lruvec *lruvec = lock_page_lruvec_irq(page, pgdat); >> >> - spin_lock_irq(&pgdat->lru_lock); >> 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; >> } else >> *isolated = 0; >> + >> + return lruvec; >> } > > But what if the page is !PageLRU? What lruvec did we just lock? like original pgdat->lru_lock, we need the lock from PageLRU racing. And it the lruvec which the page should be. > According to the comments on mem_cgroup_page_lruvec(), > > * This function is only safe when following the LRU page isolation > * and putback protocol: the LRU lock must be held, and the page must > * either be PageLRU() or the caller must have isolated/allocated it. > > and now it's being called in order to find out which LRU lock to take. > So this comment needs to be updated, if it's wrong, or this patch has > a race. Yes, the function reminder is a bit misunderstanding with new patch, How about the following changes: - * This function is only safe when following the LRU page isolation - * and putback protocol: the LRU lock must be held, and the page must - * either be PageLRU() or the caller must have isolated/allocated it. + * The caller needs to grantee the page's mem_cgroup is undisturbed during + * using. That could be done by lock_page_memcg or lock_page_lruvec. Thanks Alex
On Mon, Nov 18, 2019 at 07:55:43PM +0800, Alex Shi wrote: > 在 2019/11/16 下午12:38, Matthew Wilcox 写道: > > On Sat, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: > >> This is the main patch to replace per node lru_lock with per memcg > >> lruvec lock. It also fold the irqsave flags into lruvec. > > > > I have to say, I don't love the part where we fold the irqsave flags > > into the lruvec. I know it saves us an argument, but it opens up the > > possibility of mismatched expectations. eg we currently have: > > > > static void __split_huge_page(struct page *page, struct list_head *list, > > struct lruvec *lruvec, pgoff_t end) > > { > > ... > > spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > > > > so if we introduce a new caller, we have to be certain that this caller > > is also using lock_page_lruvec_irqsave() and not lock_page_lruvec_irq(). > > I can't think of a way to make the compiler enforce that, and if we don't, > > then we can get some odd crashes with interrupts being unexpectedly > > enabled or disabled, depending on how ->irqflags was used last. > > > > So it makes the code more subtle. And that's not a good thing. > > Hi Matthew, > > Thanks for comments! > > Here, the irqflags is bound, and belong to lruvec, merging them into together helps us to take them as whole, and thus reduce a unnecessary code clues. It's not bound to the lruvec, though. Call chain A uses it and call chain B doesn't. If it was always used by every call chain, I'd see your point, but we have call chains which don't use it, and so it adds complexity. > As your concern for a 'new' caller, since __split_huge_page is a static helper here, no distub for anyothers. Even though it's static, there may be other callers within the same file. Or somebody may decide to make it non-static in the future. I think it's actually clearer to keep the irqflags as a separate parameter. > >> +static inline struct lruvec *lock_page_lruvec_irq(struct page *page, > >> + struct pglist_data *pgdat) > >> +{ > >> + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); > >> + > >> + spin_lock_irq(&lruvec->lru_lock); > >> + > >> + return lruvec; > >> +} > > > > ... > > > >> +static struct lruvec *lock_page_lru(struct page *page, int *isolated) > >> { > >> pg_data_t *pgdat = page_pgdat(page); > >> + struct lruvec *lruvec = lock_page_lruvec_irq(page, pgdat); > >> > >> - spin_lock_irq(&pgdat->lru_lock); > >> 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; > >> } else > >> *isolated = 0; > >> + > >> + return lruvec; > >> } > > > > But what if the page is !PageLRU? What lruvec did we just lock? > > like original pgdat->lru_lock, we need the lock from PageLRU racing. And it the lruvec which the page should be. > > > > According to the comments on mem_cgroup_page_lruvec(), > > > > * This function is only safe when following the LRU page isolation > > * and putback protocol: the LRU lock must be held, and the page must > > * either be PageLRU() or the caller must have isolated/allocated it. > > > > and now it's being called in order to find out which LRU lock to take. > > So this comment needs to be updated, if it's wrong, or this patch has > > a race. > > > Yes, the function reminder is a bit misunderstanding with new patch, How about the following changes: > > - * This function is only safe when following the LRU page isolation > - * and putback protocol: the LRU lock must be held, and the page must > - * either be PageLRU() or the caller must have isolated/allocated it. > + * The caller needs to grantee the page's mem_cgroup is undisturbed during > + * using. That could be done by lock_page_memcg or lock_page_lruvec. I don't understand how lock_page_lruvec makes this guarantee. I'll look at the code again and see if I can understand that.
在 2019/11/16 下午3:03, Shakeel Butt 写道: >> +reget_lruvec: >> + 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) { >> + spin_unlock_irqrestore(&locked_lruvec->lru_lock, >> + locked_lruvec->irqflags); >> + locked_lruvec = NULL; >> + } > What guarantees the lifetime of lruvec? You should read the comment on > mem_cgroup_page_lruvec(). Have you seen the patches Hugh had shared? > Please look at the trylock_page_lruvec(). > Thanks for comments, Shakeel. lruvec lifetime is same as memcg, which allocted in mem_cgroup_alloc()->alloc_mem_cgroup_per_node_info() I have read Hugh's patchset, even not every lines. But what's point of you here? > BTW have you tested Hugh's patches? > yes, I have tried the case-lru-file-readtwice on my machine w/o containers, it show a bit more regression. Thanks Alex
On Mon, Nov 18, 2019 at 08:23:12PM +0800, Alex Shi wrote: > 在 2019/11/16 下午3:03, Shakeel Butt 写道: > >> +reget_lruvec: > >> + 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) { > >> + spin_unlock_irqrestore(&locked_lruvec->lru_lock, > >> + locked_lruvec->irqflags); > >> + locked_lruvec = NULL; > >> + } > > What guarantees the lifetime of lruvec? You should read the comment on > > mem_cgroup_page_lruvec(). Have you seen the patches Hugh had shared? > > Please look at the trylock_page_lruvec(). > > > > Thanks for comments, Shakeel. > > lruvec lifetime is same as memcg, which allocted in mem_cgroup_alloc()->alloc_mem_cgroup_per_node_info() > I have read Hugh's patchset, even not every lines. But what's point of you here? I believe Shakeel's point is that here: struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat) { ... memcg = page->mem_cgroup; there is nothing pinning the memcg, and it could be freed before dereferencing memcg->nodeinfo in mem_cgroup_page_nodeinfo().
在 2019/11/18 下午8:14, Matthew Wilcox 写道: >> Hi Matthew, >> >> Thanks for comments! >> >> Here, the irqflags is bound, and belong to lruvec, merging them into together helps us to take them as whole, and thus reduce a unnecessary code clues. > It's not bound to the lruvec, though. Call chain A uses it and call chain > B doesn't. If it was always used by every call chain, I'd see your point, > but we have call chains which don't use it, and so it adds complexity. Where is the call chain B, please? > >> As your concern for a 'new' caller, since __split_huge_page is a static helper here, no distub for anyothers. > Even though it's static, there may be other callers within the same file. > Or somebody may decide to make it non-static in the future. I think it's > actually clearer to keep the irqflags as a separate parameter. > But it's no one else using this function now. and no one get disturb, right? It's non sense to consider a 'possibility' issue.
On Mon, Nov 18, 2019 at 08:31:50PM +0800, Alex Shi wrote: > > > 在 2019/11/18 下午8:14, Matthew Wilcox 写道: > >> Hi Matthew, > >> > >> Thanks for comments! > >> > >> Here, the irqflags is bound, and belong to lruvec, merging them into together helps us to take them as whole, and thus reduce a unnecessary code clues. > > It's not bound to the lruvec, though. Call chain A uses it and call chain > > B doesn't. If it was always used by every call chain, I'd see your point, > > but we have call chains which don't use it, and so it adds complexity. > > Where is the call chain B, please? Every call chain that uses lock_page_lruvec_irq(). > >> As your concern for a 'new' caller, since __split_huge_page is a static helper here, no distub for anyothers. > > Even though it's static, there may be other callers within the same file. > > Or somebody may decide to make it non-static in the future. I think it's > > actually clearer to keep the irqflags as a separate parameter. > > > > But it's no one else using this function now. and no one get disturb, right? It's non sense to consider a 'possibility' issue. It is not nonsense to consider the complexity of the mm! Your patch makes it harder to understand unnecessarily. Please be considerate of the other programmers who must build on what you have created.
On Sat, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 62470325f9bc..cf274739e619 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -1246,6 +1246,42 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd > return lruvec; > } > > +struct lruvec *lock_page_lruvec_irq(struct page *page, > + struct pglist_data *pgdat) > +{ > + struct lruvec *lruvec; > + > +again: > + lruvec = mem_cgroup_page_lruvec(page, pgdat); > + spin_lock_irq(&lruvec->lru_lock); This isn't safe. Nothing prevents the page from being moved to a different memcg in between these two operations, and the lruvec having been freed by the time you try to acquire the spinlock. You need to use the rcu lock to dereference page->mem_cgroup and its lruvec when coming from the page like this. You also need to use page_memcg_rcu() to insert the appropriate lockless access barriers, which mem_cgroup_page_lruvec() does not do since it's designed for use with pgdat->lru_lock.
On Sat, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: > @@ -192,26 +190,17 @@ static void pagevec_lru_move_fn(struct pagevec *pvec, > void *arg) > { > int i; > - struct pglist_data *pgdat = NULL; > - struct lruvec *lruvec; > - unsigned long flags = 0; > + struct lruvec *lruvec = NULL; > > for (i = 0; i < pagevec_count(pvec); i++) { > struct page *page = pvec->pages[i]; > - struct pglist_data *pagepgdat = page_pgdat(page); > > - if (pagepgdat != pgdat) { > - if (pgdat) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > - pgdat = pagepgdat; > - spin_lock_irqsave(&pgdat->lru_lock, flags); > - } > + lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page)); > > - lruvec = mem_cgroup_page_lruvec(page, pgdat); > (*move_fn)(page, lruvec, arg); > + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); > } > - if (pgdat) > - spin_unlock_irqrestore(&pgdat->lru_lock, flags); > + > release_pages(pvec->pages, pvec->nr); > pagevec_reinit(pvec); > } Why can't you keep the locking pattern where we only drop and reacquire if the lruvec changes? It'd save a lot of locks and unlocks if most pages were from the same memcg and node, or the memory controller were unused. Thanks for running the -readtwice benchmark, by the way.
在 2019/11/19 上午12:11, Johannes Weiner 写道: > On Sat, Nov 16, 2019 at 11:15:02AM +0800, Alex Shi wrote: >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 62470325f9bc..cf274739e619 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -1246,6 +1246,42 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd >> return lruvec; >> } >> >> +struct lruvec *lock_page_lruvec_irq(struct page *page, >> + struct pglist_data *pgdat) >> +{ >> + struct lruvec *lruvec; >> + >> +again: >> + lruvec = mem_cgroup_page_lruvec(page, pgdat); >> + spin_lock_irq(&lruvec->lru_lock); > > This isn't safe. Nothing prevents the page from being moved to a > different memcg in between these two operations, and the lruvec having > been freed by the time you try to acquire the spinlock. > > You need to use the rcu lock to dereference page->mem_cgroup and its > lruvec when coming from the page like this. Hi Johannes, Yes, you are right. Thank a lot to point out this! Could we use rcu lock to guard the lruvec till lruvec->lru_lock getten? +struct lruvec *lock_page_lruvec_irq(struct page *page, + struct pglist_data *pgdat) +{ + struct lruvec *lruvec; + +again: + rcu_read_lock(); + lruvec = mem_cgroup_page_lruvec(page, pgdat); + spin_lock_irq(&lruvec->lru_lock); + rcu_read_unlock(); + + /* lruvec may changed in commit_charge() */ + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) { + spin_unlock_irq(&lruvec->lru_lock); + goto again; + } + + return lruvec; +} > > You also need to use page_memcg_rcu() to insert the appropriate > lockless access barriers, which mem_cgroup_page_lruvec() does not do > since it's designed for use with pgdat->lru_lock. > Since the page_memcg_rcu can not know it under a spin_lock, guess the following enhance is fine: @@ -1225,7 +1224,7 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd goto out; } - memcg = page->mem_cgroup; + memcg = READ_ONCE(page->mem_cgroup); /* Millions thanks! Alex
在 2019/11/18 下午8:31, Matthew Wilcox 写道: >> Thanks for comments, Shakeel. >> >> lruvec lifetime is same as memcg, which allocted in mem_cgroup_alloc()->alloc_mem_cgroup_per_node_info() >> I have read Hugh's patchset, even not every lines. But what's point of you here? > I believe Shakeel's point is that here: > > struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgdat) > { > ... > memcg = page->mem_cgroup; > > there is nothing pinning the memcg, and it could be freed before > dereferencing memcg->nodeinfo in mem_cgroup_page_nodeinfo(). That's right! I will send the fix patches for review. Thanks a lot!
在 2019/11/19 上午10:10, Daniel Jordan 写道: >> - if (pgdat) >> - spin_unlock_irqrestore(&pgdat->lru_lock, flags); >> + >> release_pages(pvec->pages, pvec->nr); >> pagevec_reinit(pvec); >> } > Why can't you keep the locking pattern where we only drop and reacquire if the > lruvec changes? It'd save a lot of locks and unlocks if most pages were from > the same memcg and node, or the memory controller were unused. > Good catching! This issue will be fixed in the next patch which introduce relock_ function. Thanks!
> >>>> As your concern for a 'new' caller, since __split_huge_page is a static helper here, no distub for anyothers. >>> Even though it's static, there may be other callers within the same file. >>> Or somebody may decide to make it non-static in the future. I think it's >>> actually clearer to keep the irqflags as a separate parameter. >>> >> >> But it's no one else using this function now. and no one get disturb, right? It's non sense to consider a 'possibility' issue. > > It is not nonsense to consider the complexity of the mm! Your patch makes > it harder to understand unnecessarily. Please be considerate of the other > programmers who must build on what you have created. > I believe the 'flags' parameter are using __split_huge_page is just for irqsave/restore of lru_lock, so move it into lruvec should be reduce the parameter jumping in caller/callee. But in another side, the flags opitimze isn't close related with lru_lock change, and better to be split out. So thanks for your comments, I will remove this part for this patchset. Thanks! Alex
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 5b86287fa069..0b32eadd0eda 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -418,6 +418,9 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg, struct lruvec *mem_cgroup_page_lruvec(struct page *, struct pglist_data *); +struct lruvec *lock_page_lruvec_irq(struct page *, struct pglist_data *); +struct lruvec *lock_page_lruvec_irqsave(struct page *, struct pglist_data *); + struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p); struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm); @@ -901,6 +904,26 @@ static inline struct lruvec *mem_cgroup_page_lruvec(struct page *page, return &pgdat->__lruvec; } +static inline struct lruvec *lock_page_lruvec_irq(struct page *page, + struct pglist_data *pgdat) +{ + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); + + spin_lock_irq(&lruvec->lru_lock); + + return lruvec; +} + +static inline struct lruvec *lock_page_lruvec_irqsave(struct page *page, + struct pglist_data *pgdat) +{ + struct lruvec *lruvec = mem_cgroup_page_lruvec(page, pgdat); + + spin_lock_irqsave(&lruvec->lru_lock, lruvec->irqflags); + + return lruvec; +} + static inline bool mm_match_cgroup(struct mm_struct *mm, struct mem_cgroup *memcg) { diff --git a/mm/compaction.c b/mm/compaction.c index d20816b21b55..eb1ad30c1bef 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -786,8 +786,7 @@ static bool too_many_isolated(pg_data_t *pgdat) pg_data_t *pgdat = cc->zone->zone_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 +846,21 @@ 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) { + spin_unlock_irqrestore(&locked_lruvec->lru_lock, + locked_lruvec->irqflags); + 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)) @@ -920,10 +929,10 @@ 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) { + spin_unlock_irqrestore(&locked_lruvec->lru_lock, + locked_lruvec->irqflags); + locked_lruvec = NULL; } if (!isolate_movable_page(page, isolate_mode)) @@ -949,10 +958,22 @@ static bool too_many_isolated(pg_data_t *pgdat) if (!(cc->gfp_mask & __GFP_FS) && page_mapping(page)) goto isolate_fail; +reget_lruvec: + 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) { + spin_unlock_irqrestore(&locked_lruvec->lru_lock, + locked_lruvec->irqflags); + locked_lruvec = NULL; + } + if (compact_lock_irqsave(&lruvec->lru_lock, + &lruvec->irqflags, cc)) + locked_lruvec = lruvec; + + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) + goto reget_lruvec; /* Try get exclusive access under lock */ if (!skip_updated) { @@ -976,7 +997,6 @@ static bool too_many_isolated(pg_data_t *pgdat) } } - lruvec = mem_cgroup_page_lruvec(page, pgdat); /* Try isolate the page */ if (__isolate_lru_page(page, isolate_mode) != 0) @@ -1017,9 +1037,10 @@ 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) { + spin_unlock_irqrestore(&locked_lruvec->lru_lock, + locked_lruvec->irqflags); + locked_lruvec = NULL; } putback_movable_pages(&cc->migratepages); cc->nr_migratepages = 0; @@ -1044,8 +1065,9 @@ static bool too_many_isolated(pg_data_t *pgdat) low_pfn = end_pfn; isolate_abort: - if (locked) - spin_unlock_irqrestore(&pgdat->lru_lock, flags); + if (locked_lruvec) + spin_unlock_irqrestore(&locked_lruvec->lru_lock, + locked_lruvec->irqflags); /* * Updated the cached scanner pfn once the pageblock has been scanned diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 13cc93785006..7e8bd6c700d2 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2495,17 +2495,13 @@ static void __split_huge_page_tail(struct page *head, int tail, } static void __split_huge_page(struct page *page, struct list_head *list, - pgoff_t end, unsigned long flags) + struct lruvec *lruvec, 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; int i; - lruvec = mem_cgroup_page_lruvec(head, pgdat); - /* complete memcg works before add pages to LRU */ mem_cgroup_split_huge_fixup(head); @@ -2554,7 +2550,7 @@ static void __split_huge_page(struct page *page, struct list_head *list, xa_unlock(&head->mapping->i_pages); } - spin_unlock_irqrestore(&pgdat->lru_lock, flags); + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); remap_page(head); @@ -2697,9 +2693,9 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) struct deferred_split *ds_queue = get_deferred_split_queue(page); struct anon_vma *anon_vma = NULL; struct address_space *mapping = NULL; + struct lruvec *lruvec; int count, mapcount, extra_pins, ret; bool mlocked; - unsigned long flags; pgoff_t end; VM_BUG_ON_PAGE(is_huge_zero_page(page), page); @@ -2766,7 +2762,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) lru_add_drain(); /* prevent PageLRU to go away from under us, and freeze lru stats */ - spin_lock_irqsave(&pgdata->lru_lock, flags); + lruvec = lock_page_lruvec_irqsave(head, pgdata); if (mapping) { XA_STATE(xas, &mapping->i_pages, page_index(head)); @@ -2797,7 +2793,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) } spin_unlock(&ds_queue->split_queue_lock); - __split_huge_page(page, list, end, flags); + __split_huge_page(page, list, lruvec, end); if (PageSwapCache(head)) { swp_entry_t entry = { .val = page_private(head) }; @@ -2816,7 +2812,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) spin_unlock(&ds_queue->split_queue_lock); fail: if (mapping) xa_unlock(&mapping->i_pages); - spin_unlock_irqrestore(&pgdata->lru_lock, flags); + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); remap_page(head); ret = -EBUSY; } diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 62470325f9bc..cf274739e619 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1246,6 +1246,42 @@ struct lruvec *mem_cgroup_page_lruvec(struct page *page, struct pglist_data *pgd return lruvec; } +struct lruvec *lock_page_lruvec_irq(struct page *page, + struct pglist_data *pgdat) +{ + struct lruvec *lruvec; + +again: + lruvec = mem_cgroup_page_lruvec(page, pgdat); + spin_lock_irq(&lruvec->lru_lock); + + /* lruvec may changed in commit_charge() */ + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) { + spin_unlock_irq(&lruvec->lru_lock); + goto again; + } + + return lruvec; +} + +struct lruvec *lock_page_lruvec_irqsave(struct page *page, + struct pglist_data *pgdat) +{ + struct lruvec *lruvec; + +again: + lruvec = mem_cgroup_page_lruvec(page, pgdat); + spin_lock_irqsave(&lruvec->lru_lock, lruvec->irqflags); + + /* lruvec may changed in commit_charge() */ + if (lruvec != mem_cgroup_page_lruvec(page, pgdat)) { + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); + goto again; + } + + return lruvec; +} + /** * mem_cgroup_update_lru_size - account for adding or removing an lru page * @lruvec: mem_cgroup per zone lru vector @@ -2571,41 +2607,43 @@ static void cancel_charge(struct mem_cgroup *memcg, unsigned int nr_pages) css_put_many(&memcg->css, nr_pages); } -static void lock_page_lru(struct page *page, int *isolated) +static struct lruvec *lock_page_lru(struct page *page, int *isolated) { pg_data_t *pgdat = page_pgdat(page); + struct lruvec *lruvec = lock_page_lruvec_irq(page, pgdat); - spin_lock_irq(&pgdat->lru_lock); 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; } else *isolated = 0; + + return lruvec; } -static void unlock_page_lru(struct page *page, int isolated) +static void unlock_page_lru(struct page *page, int isolated, + struct lruvec *locked_lruvec) { - pg_data_t *pgdat = page_pgdat(page); + struct lruvec *lruvec; - if (isolated) { - struct lruvec *lruvec; + spin_unlock_irq(&locked_lruvec->lru_lock); + lruvec = lock_page_lruvec_irq(page, page_pgdat(page)); - lruvec = mem_cgroup_page_lruvec(page, pgdat); + if (isolated) { VM_BUG_ON_PAGE(PageLRU(page), page); SetPageLRU(page); add_page_to_lru_list(page, lruvec, page_lru(page)); } - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); } static void commit_charge(struct page *page, struct mem_cgroup *memcg, bool lrucare) { int isolated; + struct lruvec *lruvec; VM_BUG_ON_PAGE(page->mem_cgroup, page); @@ -2614,7 +2652,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg, * may already be on some other mem_cgroup's LRU. Take care of it. */ if (lrucare) - lock_page_lru(page, &isolated); + lruvec = lock_page_lru(page, &isolated); /* * Nobody should be changing or seriously looking at @@ -2633,7 +2671,7 @@ static void commit_charge(struct page *page, struct mem_cgroup *memcg, page->mem_cgroup = memcg; if (lrucare) - unlock_page_lru(page, isolated); + unlock_page_lru(page, isolated, lruvec); } #ifdef CONFIG_MEMCG_KMEM @@ -2929,7 +2967,7 @@ void __memcg_kmem_uncharge(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. + * pgdat->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 a72c1eeded77..b509b80b8513 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -106,12 +106,10 @@ void mlock_vma_page(struct page *page) * Isolate a page from LRU with optional get_page() pin. * Assumes lru_lock already held and page already pinned. */ -static bool __munlock_isolate_lru_page(struct page *page, bool getpage) +static bool __munlock_isolate_lru_page(struct page *page, + struct lruvec *lruvec, bool getpage) { if (PageLRU(page)) { - struct lruvec *lruvec; - - lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); if (getpage) get_page(page); ClearPageLRU(page); @@ -183,6 +181,7 @@ unsigned int munlock_vma_page(struct page *page) { int nr_pages; pg_data_t *pgdat = page_pgdat(page); + struct lruvec *lruvec; /* For try_to_munlock() and to serialize with page migration */ BUG_ON(!PageLocked(page)); @@ -194,7 +193,7 @@ unsigned int munlock_vma_page(struct page *page) * might otherwise copy PageMlocked to part of the tail pages before * we clear it in the head page. It also stabilizes hpage_nr_pages(). */ - spin_lock_irq(&pgdat->lru_lock); + lruvec = lock_page_lruvec_irq(page, pgdat); if (!TestClearPageMlocked(page)) { /* Potentially, PTE-mapped THP: do not skip the rest PTEs */ @@ -205,15 +204,15 @@ unsigned int munlock_vma_page(struct page *page) nr_pages = hpage_nr_pages(page); __mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages); - if (__munlock_isolate_lru_page(page, true)) { - spin_unlock_irq(&pgdat->lru_lock); + if (__munlock_isolate_lru_page(page, lruvec, true)) { + spin_unlock_irq(&lruvec->lru_lock); __munlock_isolated_page(page); goto out; } __munlock_isolation_failed(page); unlock_out: - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); out: return nr_pages - 1; @@ -291,28 +290,29 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) { int i; int nr = pagevec_count(pvec); - int delta_munlocked = -nr; struct pagevec pvec_putback; + struct lruvec *lruvec = NULL; int pgrescued = 0; pagevec_init(&pvec_putback); /* Phase 1: page isolation */ - spin_lock_irq(&zone->zone_pgdat->lru_lock); for (i = 0; i < nr; i++) { struct page *page = pvec->pages[i]; + lruvec = lock_page_lruvec_irq(page, page_pgdat(page)); + if (TestClearPageMlocked(page)) { /* * We already have pin from follow_page_mask() * so we can spare the get_page() here. */ - if (__munlock_isolate_lru_page(page, false)) + if (__munlock_isolate_lru_page(page, lruvec, false)) { + __mod_zone_page_state(zone, NR_MLOCK, -1); + spin_unlock_irq(&lruvec->lru_lock); continue; - else + } else __munlock_isolation_failed(page); - } else { - delta_munlocked++; } /* @@ -323,9 +323,8 @@ static void __munlock_pagevec(struct pagevec *pvec, struct zone *zone) */ pagevec_add(&pvec_putback, pvec->pages[i]); pvec->pages[i] = NULL; + spin_unlock_irq(&lruvec->lru_lock); } - __mod_zone_page_state(zone, NR_MLOCK, delta_munlocked); - spin_unlock_irq(&zone->zone_pgdat->lru_lock); /* Now we can release pins of pages that we are not munlocking */ pagevec_release(&pvec_putback); diff --git a/mm/page_idle.c b/mm/page_idle.c index 295512465065..25f4b1cf3e0f 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -32,6 +32,7 @@ static struct page *page_idle_get_page(unsigned long pfn) { struct page *page; pg_data_t *pgdat; + struct lruvec *lruvec; if (!pfn_valid(pfn)) return NULL; @@ -42,12 +43,12 @@ static struct page *page_idle_get_page(unsigned long pfn) return NULL; pgdat = page_pgdat(page); - spin_lock_irq(&pgdat->lru_lock); + lruvec = lock_page_lruvec_irq(page, pgdat); if (unlikely(!PageLRU(page))) { put_page(page); page = NULL; } - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); return page; } diff --git a/mm/swap.c b/mm/swap.c index 5341ae93861f..60f04cb2b49e 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -62,14 +62,12 @@ static void __page_cache_release(struct page *page) if (PageLRU(page)) { pg_data_t *pgdat = page_pgdat(page); struct lruvec *lruvec; - unsigned long flags; - spin_lock_irqsave(&pgdat->lru_lock, flags); - lruvec = mem_cgroup_page_lruvec(page, pgdat); + lruvec = lock_page_lruvec_irqsave(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); + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); } __ClearPageWaiters(page); } @@ -192,26 +190,17 @@ static void pagevec_lru_move_fn(struct pagevec *pvec, void *arg) { int i; - struct pglist_data *pgdat = NULL; - struct lruvec *lruvec; - unsigned long flags = 0; + struct lruvec *lruvec = NULL; for (i = 0; i < pagevec_count(pvec); i++) { struct page *page = pvec->pages[i]; - struct pglist_data *pagepgdat = page_pgdat(page); - if (pagepgdat != pgdat) { - if (pgdat) - spin_unlock_irqrestore(&pgdat->lru_lock, flags); - pgdat = pagepgdat; - spin_lock_irqsave(&pgdat->lru_lock, flags); - } + lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page)); - lruvec = mem_cgroup_page_lruvec(page, pgdat); (*move_fn)(page, lruvec, arg); + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); } - if (pgdat) - spin_unlock_irqrestore(&pgdat->lru_lock, flags); + release_pages(pvec->pages, pvec->nr); pagevec_reinit(pvec); } @@ -325,11 +314,12 @@ 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), NULL); - spin_unlock_irq(&pgdat->lru_lock); + lruvec = lock_page_lruvec_irq(page, pgdat); + __activate_page(page, lruvec, NULL); + spin_unlock_irq(&lruvec->lru_lock); } #endif @@ -780,9 +770,7 @@ void release_pages(struct page **pages, int nr) { int i; LIST_HEAD(pages_to_free); - struct pglist_data *locked_pgdat = NULL; - struct lruvec *lruvec; - unsigned long uninitialized_var(flags); + struct lruvec *lruvec = NULL; unsigned int uninitialized_var(lock_batch); for (i = 0; i < nr; i++) { @@ -791,21 +779,22 @@ 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) { + spin_unlock_irqrestore(&lruvec->lru_lock, + lruvec->irqflags); + 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) { + spin_unlock_irqrestore(&lruvec->lru_lock, + lruvec->irqflags); + lruvec = NULL; } /* * ZONE_DEVICE pages that return 'false' from @@ -822,27 +811,25 @@ 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) { + spin_unlock_irqrestore(&lruvec->lru_lock, + lruvec->irqflags); + lruvec = NULL; } __put_compound_page(page); continue; } if (PageLRU(page)) { - struct pglist_data *pgdat = page_pgdat(page); + struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, page_pgdat(page)); - if (pgdat != locked_pgdat) { - if (locked_pgdat) - spin_unlock_irqrestore(&locked_pgdat->lru_lock, - flags); + if (new_lruvec != lruvec) { + if (lruvec) + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); lock_batch = 0; - locked_pgdat = pgdat; - spin_lock_irqsave(&locked_pgdat->lru_lock, flags); - } + lruvec = lock_page_lruvec_irqsave(page, page_pgdat(page)); - lruvec = mem_cgroup_page_lruvec(page, locked_pgdat); + } VM_BUG_ON_PAGE(!PageLRU(page), page); __ClearPageLRU(page); del_page_from_lru_list(page, lruvec, page_off_lru(page)); @@ -854,8 +841,8 @@ 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) + spin_unlock_irqrestore(&lruvec->lru_lock, lruvec->irqflags); mem_cgroup_uncharge_list(&pages_to_free); free_unref_page_list(&pages_to_free); @@ -893,7 +880,7 @@ void lru_add_page_tail(struct page *page, struct page *page_tail, VM_BUG_ON_PAGE(!PageHead(page), page); VM_BUG_ON_PAGE(PageCompound(page_tail), page); VM_BUG_ON_PAGE(PageLRU(page_tail), page); - lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); + lockdep_assert_held(&lruvec->lru_lock); if (!list) SetPageLRU(page_tail); diff --git a/mm/vmscan.c b/mm/vmscan.c index d97985262dda..3cdf343e7a27 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1755,8 +1755,7 @@ int isolate_lru_page(struct page *page) pg_data_t *pgdat = page_pgdat(page); struct lruvec *lruvec; - spin_lock_irq(&pgdat->lru_lock); - lruvec = mem_cgroup_page_lruvec(page, pgdat); + lruvec = lock_page_lruvec_irq(page, pgdat); if (PageLRU(page)) { int lru = page_lru(page); get_page(page); @@ -1764,7 +1763,7 @@ int isolate_lru_page(struct page *page) del_page_from_lru_list(page, lruvec, lru); ret = 0; } - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); } return ret; } @@ -1829,7 +1828,6 @@ 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; @@ -1840,12 +1838,11 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, VM_BUG_ON_PAGE(PageLRU(page), page); if (unlikely(!page_evictable(page))) { list_del(&page->lru); - 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; } - lruvec = mem_cgroup_page_lruvec(page, pgdat); SetPageLRU(page); lru = page_lru(page); @@ -1860,9 +1857,9 @@ static unsigned noinline_for_stack move_pages_to_lru(struct lruvec *lruvec, del_page_from_lru_list(page, lruvec, lru); if (unlikely(PageCompound(page))) { - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); (*get_compound_page_dtor(page))(page); - spin_lock_irq(&pgdat->lru_lock); + spin_lock_irq(&lruvec->lru_lock); } else list_add(&page->lru, &pages_to_free); } else { @@ -1925,7 +1922,7 @@ 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); @@ -1937,7 +1934,7 @@ static int current_may_throttle(void) if (!cgroup_reclaim(sc)) __count_vm_events(item, nr_scanned); __count_memcg_events(lruvec_memcg(lruvec), item, nr_scanned); - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); if (nr_taken == 0) return 0; @@ -1945,7 +1942,7 @@ 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); item = current_is_kswapd() ? PGSTEAL_KSWAPD : PGSTEAL_DIRECT; if (!cgroup_reclaim(sc)) @@ -1958,7 +1955,7 @@ static int current_may_throttle(void) __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(&page_list); free_unref_page_list(&page_list); @@ -2011,7 +2008,7 @@ 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); @@ -2022,7 +2019,7 @@ 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(); @@ -2068,7 +2065,7 @@ 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); /* * Count referenced pages from currently used mappings as rotated, * even though only some of them are actually re-activated. This @@ -2086,7 +2083,7 @@ 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); @@ -2371,7 +2368,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) + lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES); - spin_lock_irq(&pgdat->lru_lock); + spin_lock_irq(&lruvec->lru_lock); if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) { reclaim_stat->recent_scanned[0] /= 2; reclaim_stat->recent_rotated[0] /= 2; @@ -2392,7 +2389,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, fp = file_prio * (reclaim_stat->recent_scanned[1] + 1); fp /= reclaim_stat->recent_rotated[1] + 1; - spin_unlock_irq(&pgdat->lru_lock); + spin_unlock_irq(&lruvec->lru_lock); fraction[0] = ap; fraction[1] = fp; @@ -4285,24 +4282,25 @@ int page_evictable(struct page *page) */ 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 pglist_data *pgdat = page_pgdat(page); + struct lruvec *new_lruvec = mem_cgroup_page_lruvec(page, pgdat); + pgscanned++; - if (pagepgdat != pgdat) { - if (pgdat) - spin_unlock_irq(&pgdat->lru_lock); - pgdat = pagepgdat; - spin_lock_irq(&pgdat->lru_lock); + + if (lruvec != new_lruvec) { + if (lruvec) + spin_unlock_irq(&lruvec->lru_lock); + lruvec = new_lruvec; + spin_lock_irq(&lruvec->lru_lock); } - lruvec = mem_cgroup_page_lruvec(page, pgdat); if (!PageLRU(page) || !PageUnevictable(page)) continue; @@ -4318,10 +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); + spin_unlock_irq(&lruvec->lru_lock); } } EXPORT_SYMBOL_GPL(check_move_unevictable_pages);
This patchset move lru_lock into lruvec, give a lru_lock for each of lruvec, thus bring a lru_lock for each of memcg per node. This is the main patch to replace per node lru_lock with per memcg lruvec lock. It also fold the irqsave flags into lruvec. We introduce function lock_page_lruvec, it's same as vanilla pgdat lock when memory cgroup unset, w/o memcg, the function will keep repin the lruvec's lock to guard from page->mem_cgroup changes in page migrations between memcgs. (Thanks Hugh Dickins and Konstantin Khlebnikov reminder on this. Than the core logical is same as their previous patchs) According to Daniel Jordan's suggestion, I run 64 'dd' with on 32 containers on my 2s* 8 core * HT box with the 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 dd performance is 144MB/s, the vanilla kernel performance is 123MB/s. 17% performance increased. Signed-off-by: Alex Shi <alex.shi@linux.alibaba.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: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Chris Down <chris@chrisdown.name> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Qian Cai <cai@lca.pw> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: David Rientjes <rientjes@google.com> Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> Cc: swkhack <swkhack@gmail.com> Cc: "Potyra, Stefan" <Stefan.Potyra@elektrobit.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Colin Ian King <colin.king@canonical.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Peng Fan <peng.fan@nxp.com> Cc: Nikolay Borisov <nborisov@suse.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> Cc: Yafang Shao <laoar.shao@gmail.com> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Hugh Dickins <hughd@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org Cc: cgroups@vger.kernel.org --- include/linux/memcontrol.h | 23 ++++++++++++++ mm/compaction.c | 62 ++++++++++++++++++++++++------------ mm/huge_memory.c | 16 ++++------ mm/memcontrol.c | 64 +++++++++++++++++++++++++++++-------- mm/mlock.c | 31 +++++++++--------- mm/page_idle.c | 5 +-- mm/swap.c | 79 +++++++++++++++++++--------------------------- mm/vmscan.c | 58 ++++++++++++++++------------------ 8 files changed, 201 insertions(+), 137 deletions(-)