From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.7 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EC9B6C47255 for ; Fri, 8 May 2020 18:33:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C46DE2192A for ; Fri, 8 May 2020 18:33:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=cmpxchg-org.20150623.gappssmtp.com header.i=@cmpxchg-org.20150623.gappssmtp.com header.b="0dNh/IWj" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728174AbgEHSdW (ORCPT ); Fri, 8 May 2020 14:33:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57780 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1727857AbgEHScV (ORCPT ); Fri, 8 May 2020 14:32:21 -0400 Received: from mail-qk1-x742.google.com (mail-qk1-x742.google.com [IPv6:2607:f8b0:4864:20::742]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABBBDC05BD43 for ; Fri, 8 May 2020 11:32:21 -0700 (PDT) Received: by mail-qk1-x742.google.com with SMTP id b188so2619578qkd.9 for ; Fri, 08 May 2020 11:32:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cmpxchg-org.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=+wiSpoRwEYHspeJR8Gv0Gu4T5Xv9UOTe+wucWrpXt8k=; b=0dNh/IWjZhFeTttoqMZV3YkHGhFdx1nKm+z7iXFYwNPsE4TgXsSlPwNl2kG1f3JNT5 B80FQ1DT4047uhoF2ZBWq4o7SPVd3kgFtcKcxEImqkNDQt+DWx4KyZQcIFngsTOnhKpj dHb0jE/VejcpqnB3aOM3cUpil9G2W/fjOIzZHFlh+LBDAxMs1XgHnw+s91McJM32p5BQ lbekYEKAng1XPr9ZUs48f+qrUjZ5IgiXu+lQzYTkgVZMA5gl1TqO0l1pTDq32iDA5KT+ O8UToaKQsPLT316j4fCDASk1nFCQSWQxBr5Bo7ySM+Tmc8L7czbQ09L16kx70+rVrOLC A1zw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=+wiSpoRwEYHspeJR8Gv0Gu4T5Xv9UOTe+wucWrpXt8k=; b=nm9hwnYw4TH8WR/UJF23bh8wSrtObXsDEft6z/vsYLQnYumprv33/ZzneruJ917M+F Nf0U7dmX9VbWLOk3OP2z6C2Zxq3AYvWMLNz+MHdKB1j1sRaALoyhnE+Rvnt+ESXeox+H TqmQ6DWXyORoIOz5v/DwBs7pVeTefR62ERdTxvY/6mXG2Y6295rU8BbcysQlnQ7Mb8ZM KVfmC2o8gAwYUTf/DJ0I5KHtVqFWb71peNa5H5a1tU0AxPFVQvaoJNC+6apSttq3MjFl +/Tc8KjgPeQxNV5OyIA5wPOf0fdOrRGCpQ2LJdBiKUTbjCciIHNsec69r8wpN1kgVl95 SOYg== X-Gm-Message-State: AGi0PuYhIFFYeuOrKmjF9lxK/dP49ZU9iEEy3u12CocoRHuMXbRxBVSn JIBRciYNk84aPy8wqmpWd00gFkrZS8w= X-Google-Smtp-Source: APiQypJr8oSNAvojFc450AFWzLENI5Fu1W8Y2ox6Ymn2F1xsXhkMoaouTGdOD7X1EY8wxHXT02wEJA== X-Received: by 2002:a05:620a:1591:: with SMTP id d17mr4375296qkk.349.1588962740752; Fri, 08 May 2020 11:32:20 -0700 (PDT) Received: from localhost ([2620:10d:c091:480::1:2627]) by smtp.gmail.com with ESMTPSA id a29sm1867816qka.90.2020.05.08.11.32.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 May 2020 11:32:20 -0700 (PDT) From: Johannes Weiner To: Andrew Morton Cc: Alex Shi , Joonsoo Kim , Shakeel Butt , Hugh Dickins , Michal Hocko , "Kirill A. Shutemov" , Roman Gushchin , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: [PATCH 05/19] mm: memcontrol: convert page cache to a new mem_cgroup_charge() API Date: Fri, 8 May 2020 14:30:52 -0400 Message-Id: <20200508183105.225460-6-hannes@cmpxchg.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200508183105.225460-1-hannes@cmpxchg.org> References: <20200508183105.225460-1-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The try/commit/cancel protocol that memcg uses dates back to when pages used to be uncharged upon removal from the page cache, and thus couldn't be committed before the insertion had succeeded. Nowadays, pages are uncharged when they are physically freed; it doesn't matter whether the insertion was successful or not. For the page cache, the transaction dance has become unnecessary. Introduce a mem_cgroup_charge() function that simply charges a newly allocated page to a cgroup and sets up page->mem_cgroup in one single step. If the insertion fails, the caller doesn't have to do anything but free/put the page. Then switch the page cache over to this new API. Subsequent patches will also convert anon pages, but it needs a bit more prep work. Right now, memcg depends on page->mapping being already set up at the time of charging, so that it can maintain its own MEMCG_CACHE and MEMCG_RSS counters. For anon, page->mapping is set under the same pte lock under which the page is publishd, so a single charge point that can block doesn't work there just yet. The following prep patches will replace the private memcg counters with the generic vmstat counters, thus removing the page->mapping dependency, then complete the transition to the new single-point charge API and delete the old transactional scheme. v2: leave shmem swapcache when charging fails to avoid double IO (Joonsoo) Signed-off-by: Johannes Weiner Reviewed-by: Alex Shi --- include/linux/memcontrol.h | 10 +++++ mm/filemap.c | 24 +++++------ mm/memcontrol.c | 29 ++++++++++++- mm/shmem.c | 88 ++++++++++++++++---------------------- 4 files changed, 85 insertions(+), 66 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 30292d57c8af..57339514d960 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -379,6 +379,10 @@ int mem_cgroup_try_charge_delay(struct page *page, struct mm_struct *mm, void mem_cgroup_commit_charge(struct page *page, struct mem_cgroup *memcg, bool lrucare); void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg); + +int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, + bool lrucare); + void mem_cgroup_uncharge(struct page *page); void mem_cgroup_uncharge_list(struct list_head *page_list); @@ -893,6 +897,12 @@ static inline void mem_cgroup_cancel_charge(struct page *page, { } +static inline int mem_cgroup_charge(struct page *page, struct mm_struct *mm, + gfp_t gfp_mask, bool lrucare) +{ + return 0; +} + static inline void mem_cgroup_uncharge(struct page *page) { } diff --git a/mm/filemap.c b/mm/filemap.c index ce200386736c..ee9882509566 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -832,7 +832,6 @@ static int __add_to_page_cache_locked(struct page *page, { XA_STATE(xas, &mapping->i_pages, offset); int huge = PageHuge(page); - struct mem_cgroup *memcg; int error; void *old; @@ -840,17 +839,16 @@ static int __add_to_page_cache_locked(struct page *page, VM_BUG_ON_PAGE(PageSwapBacked(page), page); mapping_set_update(&xas, mapping); - if (!huge) { - error = mem_cgroup_try_charge(page, current->mm, - gfp_mask, &memcg); - if (error) - return error; - } - get_page(page); page->mapping = mapping; page->index = offset; + if (!huge) { + error = mem_cgroup_charge(page, current->mm, gfp_mask, false); + if (error) + goto error; + } + do { xas_lock_irq(&xas); old = xas_load(&xas); @@ -874,20 +872,18 @@ static int __add_to_page_cache_locked(struct page *page, xas_unlock_irq(&xas); } while (xas_nomem(&xas, gfp_mask & GFP_RECLAIM_MASK)); - if (xas_error(&xas)) + if (xas_error(&xas)) { + error = xas_error(&xas); goto error; + } - if (!huge) - mem_cgroup_commit_charge(page, memcg, false); trace_mm_filemap_add_to_page_cache(page); return 0; error: page->mapping = NULL; /* Leave page->index set: truncation relies upon it */ - if (!huge) - mem_cgroup_cancel_charge(page, memcg); put_page(page); - return xas_error(&xas); + return error; } ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO); diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8188d462d7ce..1d45a09b334f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6578,6 +6578,33 @@ void mem_cgroup_cancel_charge(struct page *page, struct mem_cgroup *memcg) cancel_charge(memcg, nr_pages); } +/** + * mem_cgroup_charge - charge a newly allocated page to a cgroup + * @page: page to charge + * @mm: mm context of the victim + * @gfp_mask: reclaim mode + * @lrucare: page might be on the LRU already + * + * Try to charge @page to the memcg that @mm belongs to, reclaiming + * pages according to @gfp_mask if necessary. + * + * Returns 0 on success. Otherwise, an error code is returned. + */ +int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, + bool lrucare) +{ + struct mem_cgroup *memcg; + int ret; + + VM_BUG_ON_PAGE(!page->mapping, page); + + ret = mem_cgroup_try_charge(page, mm, gfp_mask, &memcg); + if (ret) + return ret; + mem_cgroup_commit_charge(page, memcg, lrucare); + return 0; +} + struct uncharge_gather { struct mem_cgroup *memcg; unsigned long pgpgout; @@ -6625,8 +6652,6 @@ static void uncharge_batch(const struct uncharge_gather *ug) static void uncharge_page(struct page *page, struct uncharge_gather *ug) { VM_BUG_ON_PAGE(PageLRU(page), page); - VM_BUG_ON_PAGE(page_count(page) && !is_zone_device_page(page) && - !PageHWPoison(page) , page); if (!page->mem_cgroup) return; diff --git a/mm/shmem.c b/mm/shmem.c index d505b6cce4ab..afd5a057ebb7 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -605,11 +605,13 @@ static inline bool is_huge_enabled(struct shmem_sb_info *sbinfo) */ static int shmem_add_to_page_cache(struct page *page, struct address_space *mapping, - pgoff_t index, void *expected, gfp_t gfp) + pgoff_t index, void *expected, gfp_t gfp, + struct mm_struct *charge_mm) { XA_STATE_ORDER(xas, &mapping->i_pages, index, compound_order(page)); unsigned long i = 0; unsigned long nr = compound_nr(page); + int error; VM_BUG_ON_PAGE(PageTail(page), page); VM_BUG_ON_PAGE(index != round_down(index, nr), page); @@ -621,12 +623,22 @@ static int shmem_add_to_page_cache(struct page *page, page->mapping = mapping; page->index = index; + error = mem_cgroup_charge(page, charge_mm, gfp, PageSwapCache(page)); + if (error) { + if (!PageSwapCache(page) && PageTransHuge(page)) { + count_vm_event(THP_FILE_FALLBACK); + count_vm_event(THP_FILE_FALLBACK_CHARGE); + } + goto error; + } + cgroup_throttle_swaprate(page, gfp); + do { void *entry; xas_lock_irq(&xas); entry = xas_find_conflict(&xas); if (entry != expected) - xas_set_err(&xas, -EEXIST); + xas_set_err(&xas, expected ? -ENOENT : -EEXIST); xas_create_range(&xas); if (xas_error(&xas)) goto unlock; @@ -648,12 +660,15 @@ static int shmem_add_to_page_cache(struct page *page, } while (xas_nomem(&xas, gfp)); if (xas_error(&xas)) { - page->mapping = NULL; - page_ref_sub(page, nr); - return xas_error(&xas); + error = xas_error(&xas); + goto error; } return 0; +error: + page->mapping = NULL; + page_ref_sub(page, nr); + return error; } /* @@ -1619,7 +1634,6 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm; - struct mem_cgroup *memcg; struct page *page; swp_entry_t swap; int error; @@ -1664,29 +1678,23 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, goto failed; } - error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg); - if (!error) { - error = shmem_add_to_page_cache(page, mapping, index, - swp_to_radix_entry(swap), gfp); + error = shmem_add_to_page_cache(page, mapping, index, + swp_to_radix_entry(swap), gfp, + charge_mm); + if (error) { /* - * We already confirmed swap under page lock, and make - * no memory allocation here, so usually no possibility - * of error; but free_swap_and_cache() only trylocks a - * page, so it is just possible that the entry has been - * truncated or holepunched since swap was confirmed. + * We already confirmed swap under page lock, but + * free_swap_and_cache() only trylocks a page, so it + * is just possible that the entry has been truncated + * or holepunched since swap was confirmed. * shmem_undo_range() will have done some of the * unaccounting, now delete_from_swap_cache() will do * the rest. */ - if (error) { - mem_cgroup_cancel_charge(page, memcg); + if (error == -ENOENT) delete_from_swap_cache(page); - } - } - if (error) goto failed; - - mem_cgroup_commit_charge(page, memcg, true); + } spin_lock_irq(&info->lock); info->swapped--; @@ -1733,7 +1741,6 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, struct shmem_inode_info *info = SHMEM_I(inode); struct shmem_sb_info *sbinfo; struct mm_struct *charge_mm; - struct mem_cgroup *memcg; struct page *page; enum sgp_type sgp_huge = sgp; pgoff_t hindex = index; @@ -1858,21 +1865,11 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index, if (sgp == SGP_WRITE) __SetPageReferenced(page); - error = mem_cgroup_try_charge_delay(page, charge_mm, gfp, &memcg); - if (error) { - if (PageTransHuge(page)) { - count_vm_event(THP_FILE_FALLBACK); - count_vm_event(THP_FILE_FALLBACK_CHARGE); - } - goto unacct; - } error = shmem_add_to_page_cache(page, mapping, hindex, - NULL, gfp & GFP_RECLAIM_MASK); - if (error) { - mem_cgroup_cancel_charge(page, memcg); + NULL, gfp & GFP_RECLAIM_MASK, + charge_mm); + if (error) goto unacct; - } - mem_cgroup_commit_charge(page, memcg, false); lru_cache_add_anon(page); spin_lock_irq(&info->lock); @@ -2310,7 +2307,6 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, struct address_space *mapping = inode->i_mapping; gfp_t gfp = mapping_gfp_mask(mapping); pgoff_t pgoff = linear_page_index(dst_vma, dst_addr); - struct mem_cgroup *memcg; spinlock_t *ptl; void *page_kaddr; struct page *page; @@ -2360,16 +2356,10 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, if (unlikely(offset >= max_off)) goto out_release; - ret = mem_cgroup_try_charge_delay(page, dst_mm, gfp, &memcg); - if (ret) - goto out_release; - ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL, - gfp & GFP_RECLAIM_MASK); + gfp & GFP_RECLAIM_MASK, dst_mm); if (ret) - goto out_release_uncharge; - - mem_cgroup_commit_charge(page, memcg, false); + goto out_release; _dst_pte = mk_pte(page, dst_vma->vm_page_prot); if (dst_vma->vm_flags & VM_WRITE) @@ -2390,11 +2380,11 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, ret = -EFAULT; max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE); if (unlikely(offset >= max_off)) - goto out_release_uncharge_unlock; + goto out_release_unlock; ret = -EEXIST; if (!pte_none(*dst_pte)) - goto out_release_uncharge_unlock; + goto out_release_unlock; lru_cache_add_anon(page); @@ -2415,12 +2405,10 @@ static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, ret = 0; out: return ret; -out_release_uncharge_unlock: +out_release_unlock: pte_unmap_unlock(dst_pte, ptl); ClearPageDirty(page); delete_from_page_cache(page); -out_release_uncharge: - mem_cgroup_cancel_charge(page, memcg); out_release: unlock_page(page); put_page(page); -- 2.26.2