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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 05706C433EF for ; Wed, 30 Mar 2022 15:38:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348308AbiC3PkT (ORCPT ); Wed, 30 Mar 2022 11:40:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348295AbiC3PkN (ORCPT ); Wed, 30 Mar 2022 11:40:13 -0400 Received: from mail-pg1-x52b.google.com (mail-pg1-x52b.google.com [IPv6:2607:f8b0:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 45BF16BDEB for ; Wed, 30 Mar 2022 08:38:27 -0700 (PDT) Received: by mail-pg1-x52b.google.com with SMTP id q19so17898316pgm.6 for ; Wed, 30 Mar 2022 08:38:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=h81o0zrOo3MmiqLhXNQs++uBdbtx9emPgi7EUEIWoeg=; b=JXogY18B9Li/QyeeQ4h7enOzye+7Wr8M0oHfdOsyIxsicMR+wphDN2S28Ok7Vv8mdR eL333WRR6cAOAplCN9S83Sr/2pct5HkiQuApm024TGDeF3zdy8gDMgcbfc1C4EWTGo+T CTLxjMbvCmzR069ibJLzijcoTpRYGVpzxPsRdVmJoP5NfbwjQNyJuFizCykL4QX3yARm 0RFDiHzSa8dfgySYTeGQ56ULbR4LK+K0YRzlfqicbWDG0uk832apkSH7eRbg3+x2l9mB I9TRDPNd6KyLjydqjWKxWy+paxKkoOpVdsmEEcnwesmyFej03cLc66wlWa+RVW1qDRdE Fzkw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=h81o0zrOo3MmiqLhXNQs++uBdbtx9emPgi7EUEIWoeg=; b=ox421O6cTxsS9l5aZlQ88G4LR1elBaAgUaxxchhrosLfale8D3Vxk3GSAI5TUGAt4n Qt03Q4nmaZimZ2mpf5ihOxGp2RV3WcBFfBlPKhZb0zMd9dlgdsU/s6eWKfBAwM5gXPZY d2I48FnjZ0EEP4gxRQR05LT66MPofBBqok7Igl4iNOBCAcpcHaBNvRlo0V8IyhoqGijd f2tF1KNsVntmfAU9le2D3COYxH42xMoI4aJIIEQl6bVoaPpgXOPVZkuWrnmeLNrVpGDo iwbT1nVzSKcQKt1DKsOeIbtgxRA/3aXKLMMA7TdD5MJRBsmud7MlRfLloliCMBcNcTnm pn/Q== X-Gm-Message-State: AOAM533STjNYgAciEiDQ7PsDadNwyLeMA9FtOmvfIT26ed5/sEjhGddF ocpUIb+J2ZHagP/L+bhAMTMpgQ== X-Google-Smtp-Source: ABdhPJw76LGvWldqRycLoo/x5V2Cwand9sJPfGmDuBBYpLXujydBQNXxINbnTmeUG6iu8MQAG80cQg== X-Received: by 2002:a63:520c:0:b0:382:2953:a338 with SMTP id g12-20020a63520c000000b003822953a338mr6618861pgb.610.1648654706651; Wed, 30 Mar 2022 08:38:26 -0700 (PDT) Received: from FVFYT0MHHV2J.bytedance.net ([139.177.225.239]) by smtp.gmail.com with ESMTPSA id y8-20020a17090aa40800b001c6ccb2c395sm6686039pjp.9.2022.03.30.08.38.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 08:38:26 -0700 (PDT) From: Muchun Song To: corbet@lwn.net, mike.kravetz@oracle.com, akpm@linux-foundation.org, mcgrof@kernel.org, keescook@chromium.org, yzaikin@google.com, osalvador@suse.de, david@redhat.com, masahiroy@kernel.org Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, duanxiongchun@bytedance.com, smuchun@gmail.com, Muchun Song Subject: [PATCH v6 1/4] mm: hugetlb_vmemmap: introduce STRUCT_PAGE_SIZE_IS_POWER_OF_2 Date: Wed, 30 Mar 2022 23:37:42 +0800 Message-Id: <20220330153745.20465-2-songmuchun@bytedance.com> X-Mailer: git-send-email 2.32.0 (Apple Git-132) In-Reply-To: <20220330153745.20465-1-songmuchun@bytedance.com> References: <20220330153745.20465-1-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the size of "struct page" is not the power of two and this feature is enabled, then the vmemmap pages of HugeTLB will be corrupted after remapping (panic is about to happen in theory). But this only exists when !CONFIG_MEMCG && !CONFIG_SLUB on x86_64. However, it is not a conventional configuration nowadays. So it is not a real word issue, just the result of a code review. But we have to prevent anyone from configuring that combined configuration. In order to avoid many checks like "is_power_of_2 (sizeof(struct page))" through mm/hugetlb_vmemmap.c. Introduce STRUCT_PAGE_SIZE_IS_POWER_OF_2 to detect if the size of struct page is power of 2 and make this feature depends on this new macro. Then we could prevent anyone do any unexpected configuration. Signed-off-by: Muchun Song Suggested-by: Luis Chamberlain --- Kbuild | 15 ++++++++++++++- include/linux/mm_types.h | 2 ++ include/linux/page-flags.h | 3 ++- mm/hugetlb_vmemmap.c | 8 ++------ mm/hugetlb_vmemmap.h | 4 ++-- mm/struct_page_size.c | 20 ++++++++++++++++++++ 6 files changed, 42 insertions(+), 10 deletions(-) create mode 100644 mm/struct_page_size.c diff --git a/Kbuild b/Kbuild index fa441b98c9f6..7f90ba21dd51 100644 --- a/Kbuild +++ b/Kbuild @@ -24,6 +24,19 @@ $(timeconst-file): kernel/time/timeconst.bc FORCE $(call filechk,gentimeconst) ##### +# Generate struct_page_size.h. + +struct_page_size-file := include/generated/struct_page_size.h + +always-y += $(struct_page_size-file) +targets += mm/struct_page_size.s + +mm/struct_page_size.s: $(timeconst-file) $(bounds-file) + +$(struct_page_size-file): mm/struct_page_size.s FORCE + $(call filechk,offsets,__LINUX_STRUCT_PAGE_SIZE_H__) + +##### # Generate asm-offsets.h offsets-file := include/generated/asm-offsets.h @@ -31,7 +44,7 @@ offsets-file := include/generated/asm-offsets.h always-y += $(offsets-file) targets += arch/$(SRCARCH)/kernel/asm-offsets.s -arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file) +arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file) $(struct_page_size-file) $(offsets-file): arch/$(SRCARCH)/kernel/asm-offsets.s FORCE $(call filechk,offsets,__ASM_OFFSETS_H__) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 8834e38c06a4..5fbff44a4310 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -223,6 +223,7 @@ struct page { #endif } _struct_page_alignment; +#ifndef __GENERATING_STRUCT_PAGE_SIZE_IS_POWER_OF_2_H /** * struct folio - Represents a contiguous set of bytes. * @flags: Identical to the page flags. @@ -844,5 +845,6 @@ enum fault_flag { FAULT_FLAG_INSTRUCTION = 1 << 8, FAULT_FLAG_INTERRUPTIBLE = 1 << 9, }; +#endif /* !__GENERATING_STRUCT_PAGE_SIZE_IS_POWER_OF_2_H */ #endif /* _LINUX_MM_TYPES_H */ diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index fc4f294cc8d7..15fcdff0e7ee 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -12,6 +12,7 @@ #ifndef __GENERATING_BOUNDS_H #include #include +#include #endif /* !__GENERATING_BOUNDS_H */ /* @@ -190,7 +191,7 @@ enum pageflags { #ifndef __GENERATING_BOUNDS_H -#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +#if defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) && defined(STRUCT_PAGE_SIZE_IS_POWER_OF_2) DECLARE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP_DEFAULT_ON, hugetlb_free_vmemmap_enabled_key); diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 791626983c2e..951cf83010c7 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -178,6 +178,7 @@ #include "hugetlb_vmemmap.h" +#ifdef STRUCT_PAGE_SIZE_IS_POWER_OF_2 /* * There are a lot of struct page structures associated with each HugeTLB page. * For tail pages, the value of compound_head is the same. So we can reuse first @@ -194,12 +195,6 @@ EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled_key); static int __init early_hugetlb_free_vmemmap_param(char *buf) { - /* We cannot optimize if a "struct page" crosses page boundaries. */ - if (!is_power_of_2(sizeof(struct page))) { - pr_warn("cannot free vmemmap pages because \"struct page\" crosses page boundaries\n"); - return 0; - } - if (!buf) return -EINVAL; @@ -302,3 +297,4 @@ void __init hugetlb_vmemmap_init(struct hstate *h) pr_info("can free %d vmemmap pages for %s\n", h->nr_free_vmemmap_pages, h->name); } +#endif /* STRUCT_PAGE_SIZE_IS_POWER_OF_2 */ diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index cb2bef8f9e73..b137fd8b6ba4 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -10,7 +10,7 @@ #define _LINUX_HUGETLB_VMEMMAP_H #include -#ifdef CONFIG_HUGETLB_PAGE_FREE_VMEMMAP +#if defined(CONFIG_HUGETLB_PAGE_FREE_VMEMMAP) && defined(STRUCT_PAGE_SIZE_IS_POWER_OF_2) int alloc_huge_page_vmemmap(struct hstate *h, struct page *head); void free_huge_page_vmemmap(struct hstate *h, struct page *head); void hugetlb_vmemmap_init(struct hstate *h); @@ -41,5 +41,5 @@ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { return 0; } -#endif /* CONFIG_HUGETLB_PAGE_FREE_VMEMMAP */ +#endif /* CONFIG_HUGETLB_PAGE_FREE_VMEMMAP && STRUCT_PAGE_SIZE_IS_POWER_OF_2 */ #endif /* _LINUX_HUGETLB_VMEMMAP_H */ diff --git a/mm/struct_page_size.c b/mm/struct_page_size.c new file mode 100644 index 000000000000..6fc29c1227a0 --- /dev/null +++ b/mm/struct_page_size.c @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Generate definitions needed by the preprocessor. + * This code generates raw asm output which is post-processed + * to extract and format the required data. + */ + +#define __GENERATING_STRUCT_PAGE_SIZE_IS_POWER_OF_2_H +/* Include headers that define the enum constants of interest */ +#include +#include +#include + +int main(void) +{ + if (is_power_of_2(sizeof(struct page))) + DEFINE(STRUCT_PAGE_SIZE_IS_POWER_OF_2, is_power_of_2(sizeof(struct page))); + + return 0; +} -- 2.11.0