From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0F2002405F8 for ; Mon, 3 Mar 2025 16:30:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741019441; cv=none; b=scgdiHcRnUyMbv7fFBtgWjj+9E2AAZqsoQ6n3nbAXUkyo4rAqii8oLa21rU8+G+qZ40ahqd8hLfJUdjiXRhe3C10vLqamyFiNflGtvavDwAeOLdr/EFAWx0Xf1DMO+N4hZhglzQSYFRnlFUMKzmftDilvmWn3iTf+YOebSk7CLw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741019441; c=relaxed/simple; bh=8JZSTfKBKXDMVjBypXt5216219IvKwBRt9fqFMOGvw0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p/TpQGHz5V7Zpvo5A0JrxL/EGTkPDWIWoCk+W/hlU+w+fg8E3O3NC1NmqznTggnIgs3G1aV0/pUKTZrTamV9syeh7dd/AIETghLEWTqHrCSMTWoHFY+litvNbQQYLUDXdnKVzQDNl0dSwaN5acl0KSaa79VFsqY5hYZHySX26no= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=aH9VEhmJ; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="aH9VEhmJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1741019439; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=5CNQID9OyUlmGzlaLMJyJN9WCGZqSjZdKvQcCGQkCwE=; b=aH9VEhmJ/TiRrbOynvMQMb7mqcZ2W/2ir9WMwsvu2ifUNaovouM7iGMF7zwUvrZvPpMR50 a0SvWammGIDCaH34ACOU68784iv8yLmC4zhtT5SmGtW4Ru+mF2KYwhKsRMkmJgILt6LUXV +zBFUtqUJKKM0pfWlmEHNC38yfmH3c0= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-609-DURdBegIMgKe7Sx2epXQ4g-1; Mon, 03 Mar 2025 11:30:32 -0500 X-MC-Unique: DURdBegIMgKe7Sx2epXQ4g-1 X-Mimecast-MFC-AGG-ID: DURdBegIMgKe7Sx2epXQ4g_1741019430 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-4394c489babso25981955e9.1 for ; Mon, 03 Mar 2025 08:30:32 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1741019430; x=1741624230; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=5CNQID9OyUlmGzlaLMJyJN9WCGZqSjZdKvQcCGQkCwE=; b=WFsmeyNs/L9P4Z6huHGbDZUT7jl8r8m2Mu3JVl1dTfQVg3ghrWwFa3d8OQDiipjp9s nSJk8bOF0ru/oomKjY1ehi+WAYznfPDANIJR7TbRbpmyG45NcP3M6dPI7hvUIJkFQOyo 44OJ10UpF9ADscYRsg6tdcjijEebsioOH7GYwAmju6bY0udgLi9rEKfAlW8q874LB4QF LLmpF7nGb2LbF6GqDV11ZqwUPZhXtocDe0SooAjDJrx8wqx5RglHkFcm7Z1YRtx1jtWl U9HeTjfxNbhpCEoLuxj986eunf/HbMNWvGc5UPu2wEgclorLhm3TljQWJoJf2Qv4Rge+ tHiQ== X-Gm-Message-State: AOJu0YyCP6tzhQyx8gbqk7lcm2LwAX/lrq7cVaZ7xum2Q+AS5euYX+LK G/ONwgQNJ3AFunp5mlukvVqrb0LeT+k8j1+2NTK32eNxioOu9keZM8t0xyOGa8vVgSRgZ+3VCs8 dS8d4Cf4JWdNauY6kVuxsPNZwFt0MWmTzK71ewx3fGJvhq6YHDcSYHDP/sOK/uPNgFgDwdIENQt aTih+G9hM2D9etiG7q8stU6M+lzssxAy15q4zos1JlPey+ X-Gm-Gg: ASbGnctzpORAdsQ84D6pAX2U0hNFYNqtPAXPjvkCVpwynrWUfcGfrInEyE222Z7jEgY DshFPCi9Wa32BB7lf1AXSUBCKxUK4CEyd+IKs47+pzInoazhPR9lm79YMJwz1LIO+ftoSjvre2v n4XuzxKRjqIp87yq0+5KeILVe5r34A7548Pht2edOoYD64Oaqy4AR8zM1WOvdBPpYd42L47tFJa 7bEF77N7qGe80uWgjrqE5nEytXs5yets/qTdBOzQHWBsUGkXNqoBMNrUR3Wd34z//y3QADWGag+ pRNETDBalKrdlqlEfd/Na1uC1RVZJjrdVAAsHQBavFH2LGemMv2doOmQHTK1gyex1m1Yk+VRs0y 4 X-Received: by 2002:a5d:6da3:0:b0:38d:e48b:1766 with SMTP id ffacd0b85a97d-390ec7c67c4mr11859540f8f.6.1741019430427; Mon, 03 Mar 2025 08:30:30 -0800 (PST) X-Google-Smtp-Source: AGHT+IHRquSNZRyjpwgx3Bpqn4SKjwIglVAovJ799aL6PA2lqrvYWWUmjvtNcaSqxs0FHQnHdYBh0w== X-Received: by 2002:a5d:6da3:0:b0:38d:e48b:1766 with SMTP id ffacd0b85a97d-390ec7c67c4mr11859482f8f.6.1741019430024; Mon, 03 Mar 2025 08:30:30 -0800 (PST) Received: from localhost (p200300cbc7349600af274326a2162bfb.dip0.t-ipconnect.de. [2003:cb:c734:9600:af27:4326:a216:2bfb]) by smtp.gmail.com with UTF8SMTPSA id 5b1f17b1804b1-43bc4478f70sm23988695e9.0.2025.03.03.08.30.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 03 Mar 2025 08:30:29 -0800 (PST) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-doc@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, David Hildenbrand , Andrew Morton , "Matthew Wilcox (Oracle)" , Tejun Heo , Zefan Li , Johannes Weiner , =?UTF-8?q?Michal=20Koutn=C3=BD?= , Jonathan Corbet , Andy Lutomirski , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Muchun Song , "Liam R. Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn Subject: [PATCH v3 06/20] mm: move _entire_mapcount in folio to page[2] on 32bit Date: Mon, 3 Mar 2025 17:29:59 +0100 Message-ID: <20250303163014.1128035-7-david@redhat.com> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250303163014.1128035-1-david@redhat.com> References: <20250303163014.1128035-1-david@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Let's free up some space on 32bit in page[1] by moving the _pincount to page[2]. Ordinary folios only use the entire mapcount with PMD mappings, so order-1 folios don't apply. Similarly, hugetlb folios are always larger than order-1, turning the entire mapcount essentially unused for all order-1 folios. Moving it to order-1 folios will not change anything. On 32bit, simply check in folio_entire_mapcount() whether we have an order-1 folio, and return 0 in that case. Note that THPs on 32bit are not particularly common (and we don't care too much about performance), but we want to keep it working reliably, because likely we want to use large folios there as well in the future, independent of PMD leaf support. Once we dynamically allocate "struct folio", the 32bit specifics will go away again; even small folios could then have a pincount. Signed-off-by: David Hildenbrand --- include/linux/mm.h | 2 ++ include/linux/mm_types.h | 3 ++- mm/internal.h | 5 +++-- mm/page_alloc.c | 12 ++++++++---- 4 files changed, 15 insertions(+), 7 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index c1414491c0de2..53dd4f99fdabc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1333,6 +1333,8 @@ static inline int is_vmalloc_or_module_addr(const void *x) static inline int folio_entire_mapcount(const struct folio *folio) { VM_BUG_ON_FOLIO(!folio_test_large(folio), folio); + if (!IS_ENABLED(CONFIG_64BIT) && unlikely(folio_large_order(folio) == 1)) + return 0; return atomic_read(&folio->_entire_mapcount) + 1; } diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 31f466d8485bc..c83dd2f1ee25e 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -385,9 +385,9 @@ struct folio { union { struct { atomic_t _large_mapcount; - atomic_t _entire_mapcount; atomic_t _nr_pages_mapped; #ifdef CONFIG_64BIT + atomic_t _entire_mapcount; atomic_t _pincount; #endif /* CONFIG_64BIT */ }; @@ -409,6 +409,7 @@ struct folio { /* public: */ struct list_head _deferred_list; #ifndef CONFIG_64BIT + atomic_t _entire_mapcount; atomic_t _pincount; #endif /* !CONFIG_64BIT */ /* private: the union with struct page is transitional */ diff --git a/mm/internal.h b/mm/internal.h index 378464246f259..9860e65ffc945 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -719,10 +719,11 @@ static inline void prep_compound_head(struct page *page, unsigned int order) folio_set_order(folio, order); atomic_set(&folio->_large_mapcount, -1); - atomic_set(&folio->_entire_mapcount, -1); atomic_set(&folio->_nr_pages_mapped, 0); - if (IS_ENABLED(CONFIG_64BIT) || order > 1) + if (IS_ENABLED(CONFIG_64BIT) || order > 1) { atomic_set(&folio->_pincount, 0); + atomic_set(&folio->_entire_mapcount, -1); + } if (order > 1) INIT_LIST_HEAD(&folio->_deferred_list); } diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 594a552c735cd..b0739baf7b07f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -951,10 +951,6 @@ static int free_tail_page_prepare(struct page *head_page, struct page *page) switch (page - head_page) { case 1: /* the first tail page: these may be in place of ->mapping */ - if (unlikely(folio_entire_mapcount(folio))) { - bad_page(page, "nonzero entire_mapcount"); - goto out; - } if (unlikely(folio_large_mapcount(folio))) { bad_page(page, "nonzero large_mapcount"); goto out; @@ -964,6 +960,10 @@ static int free_tail_page_prepare(struct page *head_page, struct page *page) goto out; } if (IS_ENABLED(CONFIG_64BIT)) { + if (unlikely(atomic_read(&folio->_entire_mapcount) + 1)) { + bad_page(page, "nonzero entire_mapcount"); + goto out; + } if (unlikely(atomic_read(&folio->_pincount))) { bad_page(page, "nonzero pincount"); goto out; @@ -977,6 +977,10 @@ static int free_tail_page_prepare(struct page *head_page, struct page *page) goto out; } if (!IS_ENABLED(CONFIG_64BIT)) { + if (unlikely(atomic_read(&folio->_entire_mapcount) + 1)) { + bad_page(page, "nonzero entire_mapcount"); + goto out; + } if (unlikely(atomic_read(&folio->_pincount))) { bad_page(page, "nonzero pincount"); goto out; -- 2.48.1