Messages in this thread | | | Subject | Re: [v5 PATCH 4/4] mm: thp: make deferred split shrinker memcg aware | From | Yang Shi <> | Date | Tue, 20 Aug 2019 09:10:41 -0700 |
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On 8/20/19 4:06 AM, Kirill Tkhai wrote: > On 07.08.2019 05:17, Yang Shi wrote: >> Currently THP deferred split shrinker is not memcg aware, this may cause >> premature OOM with some configuration. For example the below test would >> run into premature OOM easily: >> >> $ cgcreate -g memory:thp >> $ echo 4G > /sys/fs/cgroup/memory/thp/memory/limit_in_bytes >> $ cgexec -g memory:thp transhuge-stress 4000 >> >> transhuge-stress comes from kernel selftest. >> >> It is easy to hit OOM, but there are still a lot THP on the deferred >> split queue, memcg direct reclaim can't touch them since the deferred >> split shrinker is not memcg aware. >> >> Convert deferred split shrinker memcg aware by introducing per memcg >> deferred split queue. The THP should be on either per node or per memcg >> deferred split queue if it belongs to a memcg. When the page is >> immigrated to the other memcg, it will be immigrated to the target >> memcg's deferred split queue too. >> >> Reuse the second tail page's deferred_list for per memcg list since the >> same THP can't be on multiple deferred split queues. >> >> Cc: Kirill Tkhai <ktkhai@virtuozzo.com> >> Cc: Johannes Weiner <hannes@cmpxchg.org> >> Cc: Michal Hocko <mhocko@suse.com> >> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> >> Cc: Hugh Dickins <hughd@google.com> >> Cc: Shakeel Butt <shakeelb@google.com> >> Cc: David Rientjes <rientjes@google.com> >> Cc: Qian Cai <cai@lca.pw> >> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> >> Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> > Reviewed-by: Kirill Tkhai <ktkhai@virtuozzo.com> > > But, please, see below one small suggestion. > >> --- >> include/linux/huge_mm.h | 9 ++++++ >> include/linux/memcontrol.h | 4 +++ >> include/linux/mm_types.h | 1 + >> mm/huge_memory.c | 76 +++++++++++++++++++++++++++++++++++++++------- >> mm/memcontrol.c | 24 +++++++++++++++ >> 5 files changed, 103 insertions(+), 11 deletions(-) >> >> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h >> index 45ede62..61c9ffd 100644 >> --- a/include/linux/huge_mm.h >> +++ b/include/linux/huge_mm.h >> @@ -267,6 +267,15 @@ static inline bool thp_migration_supported(void) >> return IS_ENABLED(CONFIG_ARCH_ENABLE_THP_MIGRATION); >> } >> >> +static inline struct list_head *page_deferred_list(struct page *page) >> +{ >> + /* >> + * Global or memcg deferred list in the second tail pages is >> + * occupied by compound_head. >> + */ >> + return &page[2].deferred_list; >> +} >> + >> #else /* CONFIG_TRANSPARENT_HUGEPAGE */ >> #define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; }) >> #define HPAGE_PMD_MASK ({ BUILD_BUG(); 0; }) >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> index 5771816..cace365 100644 >> --- a/include/linux/memcontrol.h >> +++ b/include/linux/memcontrol.h >> @@ -312,6 +312,10 @@ struct mem_cgroup { >> struct list_head event_list; >> spinlock_t event_list_lock; >> >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> + struct deferred_split deferred_split_queue; >> +#endif >> + >> struct mem_cgroup_per_node *nodeinfo[0]; >> /* WARNING: nodeinfo must be the last member here */ >> }; >> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h >> index 3a37a89..156640c 100644 >> --- a/include/linux/mm_types.h >> +++ b/include/linux/mm_types.h >> @@ -139,6 +139,7 @@ struct page { >> struct { /* Second tail page of compound page */ >> unsigned long _compound_pad_1; /* compound_head */ >> unsigned long _compound_pad_2; >> + /* For both global and memcg */ >> struct list_head deferred_list; >> }; >> struct { /* Page table pages */ >> diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> index e0d8e08..c9a596e 100644 >> --- a/mm/huge_memory.c >> +++ b/mm/huge_memory.c >> @@ -495,11 +495,25 @@ pmd_t maybe_pmd_mkwrite(pmd_t pmd, struct vm_area_struct *vma) >> return pmd; >> } >> >> -static inline struct list_head *page_deferred_list(struct page *page) >> +#ifdef CONFIG_MEMCG >> +static inline struct deferred_split *get_deferred_split_queue(struct page *page) >> { >> - /* ->lru in the tail pages is occupied by compound_head. */ >> - return &page[2].deferred_list; >> + struct mem_cgroup *memcg = compound_head(page)->mem_cgroup; >> + struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); >> + >> + if (memcg) >> + return &memcg->deferred_split_queue; >> + else >> + return &pgdat->deferred_split_queue; >> +} >> +#else >> +static inline struct deferred_split *get_deferred_split_queue(struct page *page) >> +{ >> + struct pglist_data *pgdat = NODE_DATA(page_to_nid(page)); >> + >> + return &pgdat->deferred_split_queue; >> } >> +#endif >> >> void prep_transhuge_page(struct page *page) >> { >> @@ -2658,7 +2672,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) >> { >> struct page *head = compound_head(page); >> struct pglist_data *pgdata = NODE_DATA(page_to_nid(head)); >> - struct deferred_split *ds_queue = &pgdata->deferred_split_queue; >> + struct deferred_split *ds_queue = get_deferred_split_queue(page); >> struct anon_vma *anon_vma = NULL; >> struct address_space *mapping = NULL; >> int count, mapcount, extra_pins, ret; >> @@ -2794,8 +2808,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list) >> >> void free_transhuge_page(struct page *page) >> { >> - struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); >> - struct deferred_split *ds_queue = &pgdata->deferred_split_queue; >> + struct deferred_split *ds_queue = get_deferred_split_queue(page); >> unsigned long flags; >> >> spin_lock_irqsave(&ds_queue->split_queue_lock, flags); >> @@ -2809,17 +2822,37 @@ void free_transhuge_page(struct page *page) >> >> void deferred_split_huge_page(struct page *page) >> { >> - struct pglist_data *pgdata = NODE_DATA(page_to_nid(page)); >> - struct deferred_split *ds_queue = &pgdata->deferred_split_queue; >> + struct deferred_split *ds_queue = get_deferred_split_queue(page); >> +#ifdef CONFIG_MEMCG >> + struct mem_cgroup *memcg = compound_head(page)->mem_cgroup; >> +#endif >> unsigned long flags; >> >> VM_BUG_ON_PAGE(!PageTransHuge(page), page); >> >> + /* >> + * The try_to_unmap() in page reclaim path might reach here too, >> + * this may cause a race condition to corrupt deferred split queue. >> + * And, if page reclaim is already handling the same page, it is >> + * unnecessary to handle it again in shrinker. >> + * >> + * Check PageSwapCache to determine if the page is being >> + * handled by page reclaim since THP swap would add the page into >> + * swap cache before calling try_to_unmap(). >> + */ >> + if (PageSwapCache(page)) >> + return; >> + >> spin_lock_irqsave(&ds_queue->split_queue_lock, flags); >> if (list_empty(page_deferred_list(page))) { >> count_vm_event(THP_DEFERRED_SPLIT_PAGE); >> list_add_tail(page_deferred_list(page), &ds_queue->split_queue); >> ds_queue->split_queue_len++; >> +#ifdef CONFIG_MEMCG >> + if (memcg) >> + memcg_set_shrinker_bit(memcg, page_to_nid(page), >> + deferred_split_shrinker.id); >> +#endif >> } >> spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags); >> } >> @@ -2827,8 +2860,19 @@ void deferred_split_huge_page(struct page *page) >> static unsigned long deferred_split_count(struct shrinker *shrink, >> struct shrink_control *sc) >> { >> + struct deferred_split *ds_queue; >> struct pglist_data *pgdata = NODE_DATA(sc->nid); >> - struct deferred_split *ds_queue = &pgdata->deferred_split_queue; >> + >> +#ifdef CONFIG_MEMCG >> + if (!sc->memcg) { >> + ds_queue = &pgdata->deferred_split_queue; >> + return READ_ONCE(ds_queue->split_queue_len); >> + } >> + >> + ds_queue = &sc->memcg->deferred_split_queue; >> +#else >> + ds_queue = &pgdata->deferred_split_queue; >> +#endif >> return READ_ONCE(ds_queue->split_queue_len); >> } > Can we write this a little more compact? > > struct deferred_split *ds_queue = &pgdata->deferred_split_queue; > > #ifdef CONFIG_MEMCG > if (sc->memcg) > ds_queue = &sc->memcg->deferred_split_queue; > #endif
Yes, sure.
> > Or just introduce a helper (something like get_sc_deferred_split_queue). > The same is in .scan method.
A helper sounds fine too, but IMHO I don't see to much benefit since just _count and _scan would call them.
> >> >> @@ -2836,12 +2880,21 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, >> struct shrink_control *sc) >> { >> struct pglist_data *pgdata = NODE_DATA(sc->nid); >> - struct deferred_split *ds_queue = &pgdata->deferred_split_queue; >> + struct deferred_split *ds_queue; >> unsigned long flags; >> LIST_HEAD(list), *pos, *next; >> struct page *page; >> int split = 0; >> >> +#ifdef CONFIG_MEMCG >> + if (sc->memcg) >> + ds_queue = &sc->memcg->deferred_split_queue; >> + else >> + ds_queue = &pgdata->deferred_split_queue; >> +#else >> + ds_queue = &pgdata->deferred_split_queue; >> +#endif >> + >> spin_lock_irqsave(&ds_queue->split_queue_lock, flags); >> /* Take pin on all head pages to avoid freeing them under us */ >> list_for_each_safe(pos, next, &ds_queue->split_queue) { >> @@ -2888,7 +2941,8 @@ static unsigned long deferred_split_scan(struct shrinker *shrink, >> .count_objects = deferred_split_count, >> .scan_objects = deferred_split_scan, >> .seeks = DEFAULT_SEEKS, >> - .flags = SHRINKER_NUMA_AWARE, >> + .flags = SHRINKER_NUMA_AWARE | SHRINKER_MEMCG_AWARE | >> + SHRINKER_NONSLAB, >> }; >> >> #ifdef CONFIG_DEBUG_FS >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index d90ded1..da4a411 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -4698,6 +4698,11 @@ static struct mem_cgroup *mem_cgroup_alloc(void) >> #ifdef CONFIG_CGROUP_WRITEBACK >> INIT_LIST_HEAD(&memcg->cgwb_list); >> #endif >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> + spin_lock_init(&memcg->deferred_split_queue.split_queue_lock); >> + INIT_LIST_HEAD(&memcg->deferred_split_queue.split_queue); >> + memcg->deferred_split_queue.split_queue_len = 0; >> +#endif >> idr_replace(&mem_cgroup_idr, memcg, memcg->id.id); >> return memcg; >> fail: >> @@ -5071,6 +5076,14 @@ static int mem_cgroup_move_account(struct page *page, >> __mod_memcg_state(to, NR_WRITEBACK, nr_pages); >> } >> >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> + if (compound && !list_empty(page_deferred_list(page))) { >> + spin_lock(&from->deferred_split_queue.split_queue_lock); >> + list_del_init(page_deferred_list(page)); >> + from->deferred_split_queue.split_queue_len--; >> + spin_unlock(&from->deferred_split_queue.split_queue_lock); >> + } >> +#endif >> /* >> * It is safe to change page->mem_cgroup here because the page >> * is referenced, charged, and isolated - we can't race with >> @@ -5079,6 +5092,17 @@ static int mem_cgroup_move_account(struct page *page, >> >> /* caller should have done css_get */ >> page->mem_cgroup = to; >> + >> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE >> + if (compound && list_empty(page_deferred_list(page))) { >> + spin_lock(&to->deferred_split_queue.split_queue_lock); >> + list_add_tail(page_deferred_list(page), >> + &to->deferred_split_queue.split_queue); >> + to->deferred_split_queue.split_queue_len++; >> + spin_unlock(&to->deferred_split_queue.split_queue_lock); >> + } >> +#endif >> + >> spin_unlock_irqrestore(&from->move_lock, flags); >> >> ret = 0; >>
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