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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 60A2EC433B4 for ; Fri, 30 Apr 2021 05:56:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 443B261463 for ; Fri, 30 Apr 2021 05:56:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229834AbhD3F5Y (ORCPT ); Fri, 30 Apr 2021 01:57:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:50082 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhD3F5Y (ORCPT ); Fri, 30 Apr 2021 01:57:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9357C610FC; Fri, 30 Apr 2021 05:56:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1619762197; bh=o7MGfZJ3jNm5GAB5uN4CRsfNb7MOsyVQkkR3K4+zvVU=; h=Date:From:To:Subject:In-Reply-To:From; b=k71XBLGzc9TAoS9qsQOzjCE6oyXvdq5Yag6Kn8qNThf4nH9xO74cZ60QhgXSPjx3I eguuXChOCVQ6dj42AiSQrI6E/UAJOLnmzHQ4AEJ2XJdmDN9QbK+kHBSuQl2LrWfVq7 BCHw+zi3/JMX0tTYvF64QPn8rBr3fWbXUgBiRB6A= Date: Thu, 29 Apr 2021 22:56:36 -0700 From: Andrew Morton To: akpm@linux-foundation.org, borntraeger@de.ibm.com, guro@fb.com, hannes@cmpxchg.org, hca@linux.ibm.com, hughd@google.com, linux-mm@kvack.org, mhocko@kernel.org, mm-commits@vger.kernel.org, sfr@canb.auug.org.au, shakeelb@google.com, torvalds@linux-foundation.org Subject: [patch 067/178] memcg: charge before adding to swapcache on swapin Message-ID: <20210430055636.gtRCScllo%akpm@linux-foundation.org> In-Reply-To: <20210429225251.02b6386d21b69255b4f6c163@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Shakeel Butt Subject: memcg: charge before adding to swapcache on swapin Currently the kernel adds the page, allocated for swapin, to the swapcache before charging the page. This is fine but now we want a per-memcg swapcache stat which is essential for folks who wants to transparently migrate from cgroup v1's memsw to cgroup v2's memory and swap counters. In addition charging a page before exposing it to other parts of the kernel is a step in the right direction. To correctly maintain the per-memcg swapcache stat, this patch has adopted to charge the page before adding it to swapcache. One challenge in this option is the failure case of add_to_swap_cache() on which we need to undo the mem_cgroup_charge(). Specifically undoing mem_cgroup_uncharge_swap() is not simple. To resolve the issue, this patch decouples the charging for swapin pages from mem_cgroup_charge(). Two new functions are introduced, mem_cgroup_swapin_charge_page() for just charging the swapin page and mem_cgroup_swapin_uncharge_swap() for uncharging the swap slot once the page has been successfully added to the swapcache. [shakeelb@google.com: set page->private before calling swap_readpage] Link: https://lkml.kernel.org/r/20210318015959.2986837-1-shakeelb@google.com Link: https://lkml.kernel.org/r/20210305212639.775498-1-shakeelb@google.com Signed-off-by: Shakeel Butt Acked-by: Roman Gushchin Acked-by: Johannes Weiner Acked-by: Hugh Dickins Tested-by: Heiko Carstens Cc: Michal Hocko Cc: Stephen Rothwell Cc: Christian Borntraeger Signed-off-by: Andrew Morton --- include/linux/memcontrol.h | 13 +++ mm/memcontrol.c | 119 ++++++++++++++++++++++------------- mm/memory.c | 16 ++-- mm/swap_state.c | 13 +-- 4 files changed, 101 insertions(+), 60 deletions(-) --- a/include/linux/memcontrol.h~memcg-charge-before-adding-to-swapcache-on-swapin +++ a/include/linux/memcontrol.h @@ -609,6 +609,9 @@ static inline bool mem_cgroup_below_min( } int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask); +int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm, + gfp_t gfp, swp_entry_t entry); +void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry); void mem_cgroup_uncharge(struct page *page); void mem_cgroup_uncharge_list(struct list_head *page_list); @@ -1112,6 +1115,16 @@ static inline int mem_cgroup_charge(stru return 0; } +static inline int mem_cgroup_swapin_charge_page(struct page *page, + struct mm_struct *mm, gfp_t gfp, swp_entry_t entry) +{ + return 0; +} + +static inline void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) +{ +} + static inline void mem_cgroup_uncharge(struct page *page) { } --- a/mm/memcontrol.c~memcg-charge-before-adding-to-swapcache-on-swapin +++ a/mm/memcontrol.c @@ -6644,6 +6644,27 @@ void mem_cgroup_calculate_protection(str atomic_long_read(&parent->memory.children_low_usage))); } +static int __mem_cgroup_charge(struct page *page, struct mem_cgroup *memcg, + gfp_t gfp) +{ + unsigned int nr_pages = thp_nr_pages(page); + int ret; + + ret = try_charge(memcg, gfp, nr_pages); + if (ret) + goto out; + + css_get(&memcg->css); + commit_charge(page, memcg); + + local_irq_disable(); + mem_cgroup_charge_statistics(memcg, page, nr_pages); + memcg_check_events(memcg, page); + local_irq_enable(); +out: + return ret; +} + /** * mem_cgroup_charge - charge a newly allocated page to a cgroup * @page: page to charge @@ -6653,55 +6674,71 @@ void mem_cgroup_calculate_protection(str * Try to charge @page to the memcg that @mm belongs to, reclaiming * pages according to @gfp_mask if necessary. * + * Do not use this for pages allocated for swapin. + * * 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) { - unsigned int nr_pages = thp_nr_pages(page); - struct mem_cgroup *memcg = NULL; - int ret = 0; + struct mem_cgroup *memcg; + int ret; if (mem_cgroup_disabled()) - goto out; + return 0; - if (PageSwapCache(page)) { - swp_entry_t ent = { .val = page_private(page), }; - unsigned short id; + memcg = get_mem_cgroup_from_mm(mm); + ret = __mem_cgroup_charge(page, memcg, gfp_mask); + css_put(&memcg->css); - /* - * Every swap fault against a single page tries to charge the - * page, bail as early as possible. shmem_unuse() encounters - * already charged pages, too. page and memcg binding is - * protected by the page lock, which serializes swap cache - * removal, which in turn serializes uncharging. - */ - VM_BUG_ON_PAGE(!PageLocked(page), page); - if (page_memcg(compound_head(page))) - goto out; - - id = lookup_swap_cgroup_id(ent); - rcu_read_lock(); - memcg = mem_cgroup_from_id(id); - if (memcg && !css_tryget_online(&memcg->css)) - memcg = NULL; - rcu_read_unlock(); - } + return ret; +} - if (!memcg) - memcg = get_mem_cgroup_from_mm(mm); +/** + * mem_cgroup_swapin_charge_page - charge a newly allocated page for swapin + * @page: page to charge + * @mm: mm context of the victim + * @gfp: reclaim mode + * @entry: swap entry for which the page is allocated + * + * This function charges a page allocated for swapin. Please call this before + * adding the page to the swapcache. + * + * Returns 0 on success. Otherwise, an error code is returned. + */ +int mem_cgroup_swapin_charge_page(struct page *page, struct mm_struct *mm, + gfp_t gfp, swp_entry_t entry) +{ + struct mem_cgroup *memcg; + unsigned short id; + int ret; - ret = try_charge(memcg, gfp_mask, nr_pages); - if (ret) - goto out_put; + if (mem_cgroup_disabled()) + return 0; - css_get(&memcg->css); - commit_charge(page, memcg); + id = lookup_swap_cgroup_id(entry); + rcu_read_lock(); + memcg = mem_cgroup_from_id(id); + if (!memcg || !css_tryget_online(&memcg->css)) + memcg = get_mem_cgroup_from_mm(mm); + rcu_read_unlock(); - local_irq_disable(); - mem_cgroup_charge_statistics(memcg, page, nr_pages); - memcg_check_events(memcg, page); - local_irq_enable(); + ret = __mem_cgroup_charge(page, memcg, gfp); + css_put(&memcg->css); + return ret; +} + +/* + * mem_cgroup_swapin_uncharge_swap - uncharge swap slot + * @entry: swap entry for which the page is charged + * + * Call this function after successfully adding the charged page to swapcache. + * + * Note: This function assumes the page for which swap slot is being uncharged + * is order 0 page. + */ +void mem_cgroup_swapin_uncharge_swap(swp_entry_t entry) +{ /* * Cgroup1's unified memory+swap counter has been charged with the * new swapcache page, finish the transfer by uncharging the swap @@ -6714,20 +6751,14 @@ int mem_cgroup_charge(struct page *page, * correspond 1:1 to page and swap slot lifetimes: we charge the * page to memory here, and uncharge swap when the slot is freed. */ - if (do_memsw_account() && PageSwapCache(page)) { - swp_entry_t entry = { .val = page_private(page) }; + if (!mem_cgroup_disabled() && do_memsw_account()) { /* * The swap entry might not get freed for a long time, * let's not wait for it. The page already received a * memory+swap charge, drop the swap entry duplicate. */ - mem_cgroup_uncharge_swap(entry, nr_pages); + mem_cgroup_uncharge_swap(entry, 1); } - -out_put: - css_put(&memcg->css); -out: - return ret; } struct uncharge_gather { --- a/mm/memory.c~memcg-charge-before-adding-to-swapcache-on-swapin +++ a/mm/memory.c @@ -3309,28 +3309,26 @@ vm_fault_t do_swap_page(struct vm_fault page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address); if (page) { - int err; - __SetPageLocked(page); __SetPageSwapBacked(page); - set_page_private(page, entry.val); - /* Tell memcg to use swap ownership records */ - SetPageSwapCache(page); - err = mem_cgroup_charge(page, vma->vm_mm, - GFP_KERNEL); - ClearPageSwapCache(page); - if (err) { + if (mem_cgroup_swapin_charge_page(page, + vma->vm_mm, GFP_KERNEL, entry)) { ret = VM_FAULT_OOM; goto out_page; } + mem_cgroup_swapin_uncharge_swap(entry); shadow = get_shadow_from_swap_cache(entry); if (shadow) workingset_refault(page, shadow); lru_cache_add(page); + + /* To provide entry to swap_readpage() */ + set_page_private(page, entry.val); swap_readpage(page, true); + set_page_private(page, 0); } } else { page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, --- a/mm/swap_state.c~memcg-charge-before-adding-to-swapcache-on-swapin +++ a/mm/swap_state.c @@ -497,16 +497,14 @@ struct page *__read_swap_cache_async(swp __SetPageLocked(page); __SetPageSwapBacked(page); - /* May fail (-ENOMEM) if XArray node allocation failed. */ - if (add_to_swap_cache(page, entry, gfp_mask & GFP_RECLAIM_MASK, &shadow)) { - put_swap_page(page, entry); + if (mem_cgroup_swapin_charge_page(page, NULL, gfp_mask, entry)) goto fail_unlock; - } - if (mem_cgroup_charge(page, NULL, gfp_mask)) { - delete_from_swap_cache(page); + /* May fail (-ENOMEM) if XArray node allocation failed. */ + if (add_to_swap_cache(page, entry, gfp_mask & GFP_RECLAIM_MASK, &shadow)) goto fail_unlock; - } + + mem_cgroup_swapin_uncharge_swap(entry); if (shadow) workingset_refault(page, shadow); @@ -517,6 +515,7 @@ struct page *__read_swap_cache_async(swp return page; fail_unlock: + put_swap_page(page, entry); unlock_page(page); put_page(page); return NULL; _