From patchwork Mon May 9 15:47:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Minchan Kim X-Patchwork-Id: 12843814 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 11797C433EF for ; Mon, 9 May 2022 15:47:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 8F4D26B0072; Mon, 9 May 2022 11:47:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8A4606B0073; Mon, 9 May 2022 11:47:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6F7256B0074; Mon, 9 May 2022 11:47:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id 5EC0B6B0072 for ; Mon, 9 May 2022 11:47:16 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 59C1830EE1 for ; Mon, 9 May 2022 15:47:15 +0000 (UTC) X-FDA: 79446633630.10.206DE58 Received: from mail-pg1-f177.google.com (mail-pg1-f177.google.com [209.85.215.177]) by imf22.hostedemail.com (Postfix) with ESMTP id 37E14C0084 for ; Mon, 9 May 2022 15:47:13 +0000 (UTC) Received: by mail-pg1-f177.google.com with SMTP id e5so12386881pgc.5 for ; Mon, 09 May 2022 08:47:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=uyMRuvLAt7fSYWS4NjY6cZpWUg/MdUGhOgLljV2w6ws=; b=LLt+c2vKqaXwx1e+MsYyKhYWO7DsCM1hCAE7zUqEX5P29E2dnNQIJbsUDbjjl6FsQK LIWJJ5cdx36aQO212/ANzBJlbun402/3V1tKenS9LI/PpkS7MCHg/6qw4kR17vong1Zn jYrxydHM6ZTQSjrZ5Ee5bs1x7kfRdxDG3Nzk+NsMeMXlqt2Ib5J59GSb59lXPPWdQ7v5 NIEpfEsXss/ymnR+dLnxBSES7CVWDNe15ufw1GRCEKdXiwf7Fzdmlap2CHFdRQGzUop0 mkm7U+2hjnrHcdsUGE5rdpy/UaMgzREd1VRA5YacyW/VA5xejZP7ZPDqTkV7vg9d+E3e MAww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :mime-version:content-transfer-encoding; bh=uyMRuvLAt7fSYWS4NjY6cZpWUg/MdUGhOgLljV2w6ws=; b=LLR4mcKO+Hu/jCnXfASND4nEf9G+W1Qihes/S4x95PW0PdBwk6cSXVTXTLSidGtSF/ 6uf+065kEp20D4QT1flAoQXv+BbUJNeQDbnBYDUf9OaCC9GeFlbV1e/wRjIhG7sjLk7P vmGa+EDbJiUxOF8cM+2+85OVWQT0qC4E7fuvFAXfuU2OcBFynWhfxXZGmkRd3Pk2faDk RZ9JBrqhfDRcwTVsQ6NXoVpkpv0xSScT5ThTRYhdFrmXLIy7fsoMGmQ+hfyX+SFhh1MM VqpL/zBZTp4XIGGmPMAlY8e3YwGTKkhLt2GlKAo6B+8utJ6PPTPjAito0Be45noPifDd v1Dw== X-Gm-Message-State: AOAM530VHnkNaVzNCiSrik7YL9M68pgHQUxgNhakI1vpXz90fPqbhKAf QdjsmN6a5TEuTVxqNwXb6Mw= X-Google-Smtp-Source: ABdhPJyR1OMno8nnjICKjm47ORw7U7Vsiya7atr1SIFsRHMptbAQaxIzejLMwf+45QEsgjwNbPFaiA== X-Received: by 2002:a05:6a00:349b:b0:50e:570:180e with SMTP id cp27-20020a056a00349b00b0050e0570180emr16803405pfb.13.1652111233642; Mon, 09 May 2022 08:47:13 -0700 (PDT) Received: from bbox-1.mtv.corp.google.com ([2620:15c:211:201:3704:694b:acc0:e064]) by smtp.gmail.com with ESMTPSA id n10-20020a170902e54a00b0015e8d4eb256sm8647plf.160.2022.05.09.08.47.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 09 May 2022 08:47:13 -0700 (PDT) From: Minchan Kim To: Andrew Morton Cc: LKML , linux-mm , Suren Baghdasaryan , Michal Hocko , John Dias , Tim Murray , Matthew Wilcox , Vladimir Davydov , Minchan Kim Subject: [PATCH v2] mm: don't be stuck to rmap lock on reclaim path Date: Mon, 9 May 2022 08:47:10 -0700 Message-Id: <20220509154710.4132957-1-minchan@kernel.org> X-Mailer: git-send-email 2.36.0.512.ge40c2bad7a-goog MIME-Version: 1.0 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 37E14C0084 X-Stat-Signature: gzghrij3mjzcyhmk39ukj4b9wfas7seq X-Rspam-User: Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=LLt+c2vK; spf=pass (imf22.hostedemail.com: domain of minchan.kim@gmail.com designates 209.85.215.177 as permitted sender) smtp.mailfrom=minchan.kim@gmail.com; dmarc=fail reason="SPF not aligned (relaxed), DKIM not aligned (relaxed)" header.from=kernel.org (policy=none) X-HE-Tag: 1652111233-940348 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The rmap locks(i_mmap_rwsem and anon_vma->root->rwsem) could be contented under memory pressure if processes keep working on their vmas(e.g., fork, mmap, munmap). It makes reclaim path stuck. In our real workload traces, we see kswapd is waiting the lock for 300ms+(a sec as worst case) and it makes other processes entering direct reclaim, which were also stuck on the lock. This patch makes LRU aging path try_lock mode like shink_page_list so the reclaim context will keep working with next LRU pages without being stuck. Since this patch introduces a new "contended" field as out-param along with try_lock in-param in rmap_walk_control, it's not immutable any longer if the try_lock is set so remove const keywords on rmap related functions. Since rmap walking is already expensive operation, I doubt the const would help sizable benefit( And we didn't have it until 5.17). Signed-off-by: Minchan Kim --- include/linux/fs.h | 5 +++++ include/linux/ksm.h | 4 ++-- include/linux/rmap.h | 28 +++++++++++++++++------- mm/ksm.c | 10 +++++++-- mm/memory-failure.c | 2 +- mm/page_idle.c | 7 ++---- mm/rmap.c | 52 ++++++++++++++++++++++++++++++++++---------- mm/vmscan.c | 6 ++++- 8 files changed, 84 insertions(+), 30 deletions(-) diff --git a/include/linux/fs.h b/include/linux/fs.h index f5ec00b2f073..5a169066f463 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -477,6 +477,11 @@ static inline void i_mmap_unlock_write(struct address_space *mapping) up_write(&mapping->i_mmap_rwsem); } +static inline int i_mmap_trylock_read(struct address_space *mapping) +{ + return down_read_trylock(&mapping->i_mmap_rwsem); +} + static inline void i_mmap_lock_read(struct address_space *mapping) { down_read(&mapping->i_mmap_rwsem); diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 0630e545f4cb..0b4f17418f64 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -51,7 +51,7 @@ static inline void ksm_exit(struct mm_struct *mm) struct page *ksm_might_need_to_copy(struct page *page, struct vm_area_struct *vma, unsigned long address); -void rmap_walk_ksm(struct folio *folio, const struct rmap_walk_control *rwc); +void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc); void folio_migrate_ksm(struct folio *newfolio, struct folio *folio); #else /* !CONFIG_KSM */ @@ -79,7 +79,7 @@ static inline struct page *ksm_might_need_to_copy(struct page *page, } static inline void rmap_walk_ksm(struct folio *folio, - const struct rmap_walk_control *rwc) + struct rmap_walk_control *rwc) { } diff --git a/include/linux/rmap.h b/include/linux/rmap.h index cbe279a6f0de..9ec23138e410 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -128,6 +128,11 @@ static inline void anon_vma_lock_read(struct anon_vma *anon_vma) down_read(&anon_vma->root->rwsem); } +static inline int anon_vma_trylock_read(struct anon_vma *anon_vma) +{ + return down_read_trylock(&anon_vma->root->rwsem); +} + static inline void anon_vma_unlock_read(struct anon_vma *anon_vma) { up_read(&anon_vma->root->rwsem); @@ -366,17 +371,14 @@ int pfn_mkclean_range(unsigned long pfn, unsigned long nr_pages, pgoff_t pgoff, void remove_migration_ptes(struct folio *src, struct folio *dst, bool locked); -/* - * Called by memory-failure.c to kill processes. - */ -struct anon_vma *folio_lock_anon_vma_read(struct folio *folio); -void page_unlock_anon_vma_read(struct anon_vma *anon_vma); int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); /* * rmap_walk_control: To control rmap traversing for specific needs * * arg: passed to rmap_one() and invalid_vma() + * try_lock: bail out if the rmap lock is contended + * contended: indicate the rmap traversal bailed out due to lock contention * rmap_one: executed on each vma where page is mapped * done: for checking traversing termination condition * anon_lock: for getting anon_lock by optimized way rather than default @@ -384,6 +386,8 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma); */ struct rmap_walk_control { void *arg; + bool try_lock; + bool contended; /* * Return false if page table scanning in rmap_walk should be stopped. * Otherwise, return true. @@ -391,12 +395,20 @@ struct rmap_walk_control { bool (*rmap_one)(struct folio *folio, struct vm_area_struct *vma, unsigned long addr, void *arg); int (*done)(struct folio *folio); - struct anon_vma *(*anon_lock)(struct folio *folio); + struct anon_vma *(*anon_lock)(struct folio *folio, + struct rmap_walk_control *rwc); bool (*invalid_vma)(struct vm_area_struct *vma, void *arg); }; -void rmap_walk(struct folio *folio, const struct rmap_walk_control *rwc); -void rmap_walk_locked(struct folio *folio, const struct rmap_walk_control *rwc); +void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc); +void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc); + +/* + * Called by memory-failure.c to kill processes. + */ +struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, + struct rmap_walk_control *rwc); +void page_unlock_anon_vma_read(struct anon_vma *anon_vma); #else /* !CONFIG_MMU */ diff --git a/mm/ksm.c b/mm/ksm.c index ee607d3f8720..26da7f813f23 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2614,7 +2614,7 @@ struct page *ksm_might_need_to_copy(struct page *page, return new_page; } -void rmap_walk_ksm(struct folio *folio, const struct rmap_walk_control *rwc) +void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc) { struct stable_node *stable_node; struct rmap_item *rmap_item; @@ -2638,7 +2638,13 @@ void rmap_walk_ksm(struct folio *folio, const struct rmap_walk_control *rwc) struct vm_area_struct *vma; cond_resched(); - anon_vma_lock_read(anon_vma); + if (!anon_vma_trylock_read(anon_vma)) { + if (rwc->try_lock) { + rwc->contended = true; + return; + } + anon_vma_lock_read(anon_vma); + } anon_vma_interval_tree_foreach(vmac, &anon_vma->rb_root, 0, ULONG_MAX) { unsigned long addr; diff --git a/mm/memory-failure.c b/mm/memory-failure.c index a83d32bbc567..09d60bc93140 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -485,7 +485,7 @@ static void collect_procs_anon(struct page *page, struct list_head *to_kill, struct anon_vma *av; pgoff_t pgoff; - av = folio_lock_anon_vma_read(folio); + av = folio_lock_anon_vma_read(folio, NULL); if (av == NULL) /* Not actually mapped anymore */ return; diff --git a/mm/page_idle.c b/mm/page_idle.c index fc0435abf909..fdff8c6dcd2d 100644 --- a/mm/page_idle.c +++ b/mm/page_idle.c @@ -86,11 +86,8 @@ static bool page_idle_clear_pte_refs_one(struct folio *folio, static void page_idle_clear_pte_refs(struct page *page) { struct folio *folio = page_folio(page); - /* - * Since rwc.arg is unused, rwc is effectively immutable, so we - * can make it static const to save some cycles and stack. - */ - static const struct rmap_walk_control rwc = { + + static struct rmap_walk_control rwc = { .rmap_one = page_idle_clear_pte_refs_one, .anon_lock = folio_lock_anon_vma_read, }; diff --git a/mm/rmap.c b/mm/rmap.c index 61e63db5dc6f..d4cf3ea1b616 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -527,9 +527,11 @@ struct anon_vma *page_get_anon_vma(struct page *page) * * Its a little more complex as it tries to keep the fast path to a single * atomic op -- the trylock. If we fail the trylock, we fall back to getting a - * reference like with page_get_anon_vma() and then block on the mutex. + * reference like with page_get_anon_vma() and then block on the mutex + * on !rwc->try_lock case. */ -struct anon_vma *folio_lock_anon_vma_read(struct folio *folio) +struct anon_vma *folio_lock_anon_vma_read(struct folio *folio, + struct rmap_walk_control *rwc) { struct anon_vma *anon_vma = NULL; struct anon_vma *root_anon_vma; @@ -557,6 +559,12 @@ struct anon_vma *folio_lock_anon_vma_read(struct folio *folio) goto out; } + if (rwc && rwc->try_lock) { + anon_vma = NULL; + rwc->contended = true; + goto out; + } + /* trylock failed, we got to sleep */ if (!atomic_inc_not_zero(&anon_vma->refcount)) { anon_vma = NULL; @@ -883,7 +891,8 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg) * * Quick test_and_clear_referenced for all mappings of a folio, * - * Return: The number of mappings which referenced the folio. + * Return: The number of mappings which referenced the folio. Return -1 if + * the function bailed out due to rmap lock contention. */ int folio_referenced(struct folio *folio, int is_locked, struct mem_cgroup *memcg, unsigned long *vm_flags) @@ -897,6 +906,7 @@ int folio_referenced(struct folio *folio, int is_locked, .rmap_one = folio_referenced_one, .arg = (void *)&pra, .anon_lock = folio_lock_anon_vma_read, + .try_lock = true, }; *vm_flags = 0; @@ -927,7 +937,7 @@ int folio_referenced(struct folio *folio, int is_locked, if (we_locked) folio_unlock(folio); - return pra.referenced; + return rwc.contended ? -1 : pra.referenced; } static int page_vma_mkclean_one(struct page_vma_mapped_walk *pvmw) @@ -2307,12 +2317,12 @@ void __put_anon_vma(struct anon_vma *anon_vma) } static struct anon_vma *rmap_walk_anon_lock(struct folio *folio, - const struct rmap_walk_control *rwc) + struct rmap_walk_control *rwc) { struct anon_vma *anon_vma; if (rwc->anon_lock) - return rwc->anon_lock(folio); + return rwc->anon_lock(folio, rwc); /* * Note: remove_migration_ptes() cannot use folio_lock_anon_vma_read() @@ -2324,7 +2334,17 @@ static struct anon_vma *rmap_walk_anon_lock(struct folio *folio, if (!anon_vma) return NULL; + if (anon_vma_trylock_read(anon_vma)) + goto out; + + if (rwc->try_lock) { + anon_vma = NULL; + rwc->contended = true; + goto out; + } + anon_vma_lock_read(anon_vma); +out: return anon_vma; } @@ -2338,7 +2358,7 @@ static struct anon_vma *rmap_walk_anon_lock(struct folio *folio, * contained in the anon_vma struct it points to. */ static void rmap_walk_anon(struct folio *folio, - const struct rmap_walk_control *rwc, bool locked) + struct rmap_walk_control *rwc, bool locked) { struct anon_vma *anon_vma; pgoff_t pgoff_start, pgoff_end; @@ -2386,7 +2406,7 @@ static void rmap_walk_anon(struct folio *folio, * contained in the address_space struct it points to. */ static void rmap_walk_file(struct folio *folio, - const struct rmap_walk_control *rwc, bool locked) + struct rmap_walk_control *rwc, bool locked) { struct address_space *mapping = folio_mapping(folio); pgoff_t pgoff_start, pgoff_end; @@ -2405,8 +2425,18 @@ static void rmap_walk_file(struct folio *folio, pgoff_start = folio_pgoff(folio); pgoff_end = pgoff_start + folio_nr_pages(folio) - 1; - if (!locked) + if (!locked) { + if (i_mmap_trylock_read(mapping)) + goto lookup; + + if (rwc->try_lock) { + rwc->contended = true; + return; + } + i_mmap_lock_read(mapping); + } +lookup: vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff_start, pgoff_end) { unsigned long address = vma_address(&folio->page, vma); @@ -2428,7 +2458,7 @@ static void rmap_walk_file(struct folio *folio, i_mmap_unlock_read(mapping); } -void rmap_walk(struct folio *folio, const struct rmap_walk_control *rwc) +void rmap_walk(struct folio *folio, struct rmap_walk_control *rwc) { if (unlikely(folio_test_ksm(folio))) rmap_walk_ksm(folio, rwc); @@ -2439,7 +2469,7 @@ void rmap_walk(struct folio *folio, const struct rmap_walk_control *rwc) } /* Like rmap_walk, but caller holds relevant rmap lock */ -void rmap_walk_locked(struct folio *folio, const struct rmap_walk_control *rwc) +void rmap_walk_locked(struct folio *folio, struct rmap_walk_control *rwc) { /* no ksm support for now */ VM_BUG_ON_FOLIO(folio_test_ksm(folio), folio); diff --git a/mm/vmscan.c b/mm/vmscan.c index c6918fff06e1..e68c5715270a 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1391,6 +1391,10 @@ static enum page_references folio_check_references(struct folio *folio, if (vm_flags & VM_LOCKED) return PAGEREF_ACTIVATE; + /* page_referenced didn't work due to lock contention */ + if (referenced_ptes == -1) + return PAGEREF_KEEP; + if (referenced_ptes) { /* * All mapped folios start out with page table @@ -2492,7 +2496,7 @@ static void shrink_active_list(unsigned long nr_to_scan, } if (folio_referenced(folio, 0, sc->target_mem_cgroup, - &vm_flags)) { + &vm_flags) > 0) { /* * Identify referenced, file-backed active pages and * give them one more trip around the active list. So