From nobody Fri Jun 19 20:14:40 2026 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: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 Reported-by: kernel test robot --- 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) =20 ##### +# Generate struct_page_size.h. + +struct_page_size-file :=3D include/generated/struct_page_size.h + +always-y +=3D $(struct_page_size-file) +targets +=3D 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 =20 offsets-file :=3D include/generated/asm-offsets.h @@ -31,7 +44,7 @@ offsets-file :=3D include/generated/asm-offsets.h always-y +=3D $(offsets-file) targets +=3D arch/$(SRCARCH)/kernel/asm-offsets.s =20 -arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file) +arch/$(SRCARCH)/kernel/asm-offsets.s: $(timeconst-file) $(bounds-file) $(s= truct_page_size-file) =20 $(offsets-file): arch/$(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; =20 +#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 =3D 1 << 8, FAULT_FLAG_INTERRUPTIBLE =3D 1 << 9, }; +#endif /* !__GENERATING_STRUCT_PAGE_SIZE_IS_POWER_OF_2_H */ =20 #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 */ =20 /* @@ -190,7 +191,7 @@ enum pageflags { =20 #ifndef __GENERATING_BOUNDS_H =20 -#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); =20 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 @@ =20 #include "hugetlb_vmemmap.h" =20 +#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); =20 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; =20 @@ -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 =20 -#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(s= truct 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; +} --=20 2.11.0 From nobody Fri Jun 19 20:14:40 2026 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 7C26AC433EF for ; Wed, 30 Mar 2022 15:38:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348325AbiC3Pk2 (ORCPT ); Wed, 30 Mar 2022 11:40:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39934 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348297AbiC3PkT (ORCPT ); Wed, 30 Mar 2022 11:40:19 -0400 Received: from mail-pg1-x52f.google.com (mail-pg1-x52f.google.com [IPv6:2607:f8b0:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1818C5FAE for ; Wed, 30 Mar 2022 08:38:32 -0700 (PDT) Received: by mail-pg1-x52f.google.com with SMTP id o13so17866275pgc.12 for ; Wed, 30 Mar 2022 08:38:32 -0700 (PDT) DKIM-Signature: v=1; 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Wed, 30 Mar 2022 08:38:31 -0700 (PDT) Received: from FVFYT0MHHV2J.bytedance.net ([139.177.225.239]) by smtp.gmail.com with ESMTPSA id y8-20020a17090aa40800b001c6ccb2c395sm6686039pjp.9.2022.03.30.08.38.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Mar 2022 08:38:31 -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 2/4] mm: memory_hotplug: override memmap_on_memory when hugetlb_free_vmemmap=on Date: Wed, 30 Mar 2022 23:37:43 +0800 Message-Id: <20220330153745.20465-3-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: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" When "hugetlb_free_vmemmap=3Don" and "memory_hotplug.memmap_on_memory" are both passed to boot cmdline, the variable of "memmap_on_memory" will be set to 1 even if the vmemmap pages will not be allocated from the hotadded memory since the former takes precedence over the latter. In the next patch, we want to enable or disable the feature of freeing vmemmap pages of HugeTLB via sysctl. We need a way to know if the feature of memory_hotplug.memmap_on_memory is enabled when enabling the feature of freeing vmemmap pages since those two features are not compatible, however, the variable of "memmap_on_memory" cannot indicate this nowadays. Do not set "memmap_on_memory" to 1 when both parameters are passed to cmdline, in this case, "memmap_on_memory" could indicate if this feature is enabled by the users. Also introduce mhp_memmap_on_memory() helper to move the definition of "memmap_on_memory" to the scope of CONFIG_MHP_MEMMAP_ON_MEMORY. In the next patch, mhp_memmap_on_memory() will also be exported to be used in hugetlb_vmemmap.c. Signed-off-by: Muchun Song --- mm/memory_hotplug.c | 32 ++++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 416b38ca8def..da594b382829 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -42,14 +42,36 @@ #include "internal.h" #include "shuffle.h" =20 +#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY +static int memmap_on_memory_set(const char *val, const struct kernel_param= *kp) +{ + if (hugetlb_free_vmemmap_enabled()) + return 0; + return param_set_bool(val, kp); +} + +static const struct kernel_param_ops memmap_on_memory_ops =3D { + .flags =3D KERNEL_PARAM_OPS_FL_NOARG, + .set =3D memmap_on_memory_set, + .get =3D param_get_bool, +}; =20 /* * memory_hotplug.memmap_on_memory parameter */ static bool memmap_on_memory __ro_after_init; -#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY -module_param(memmap_on_memory, bool, 0444); +module_param_cb(memmap_on_memory, &memmap_on_memory_ops, &memmap_on_memory= , 0444); MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hot= plug"); + +static inline bool mhp_memmap_on_memory(void) +{ + return memmap_on_memory; +} +#else +static inline bool mhp_memmap_on_memory(void) +{ + return false; +} #endif =20 enum { @@ -1288,9 +1310,7 @@ bool mhp_supports_memmap_on_memory(unsigned long size) * altmap as an alternative source of memory, and we do not exactly * populate a single PMD. */ - return memmap_on_memory && - !hugetlb_free_vmemmap_enabled() && - IS_ENABLED(CONFIG_MHP_MEMMAP_ON_MEMORY) && + return mhp_memmap_on_memory() && size =3D=3D memory_block_size_bytes() && IS_ALIGNED(vmemmap_size, PMD_SIZE) && IS_ALIGNED(remaining_size, (pageblock_nr_pages << PAGE_SHIFT)); @@ -2074,7 +2094,7 @@ static int __ref try_remove_memory(u64 start, u64 siz= e) * We only support removing memory added with MHP_MEMMAP_ON_MEMORY in * the same granularity it was added - a single memory block. */ - if (memmap_on_memory) { + if (mhp_memmap_on_memory()) { nr_vmemmap_pages =3D walk_memory_blocks(start, size, NULL, get_nr_vmemmap_pages_cb); if (nr_vmemmap_pages) { --=20 2.11.0 From nobody Fri Jun 19 20:14:40 2026 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 D9CE7C433F5 for ; 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Wed, 30 Mar 2022 08:38:36 -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 3/4] sysctl: allow to set extra1 to SYSCTL_ONE Date: Wed, 30 Mar 2022 23:37:44 +0800 Message-Id: <20220330153745.20465-4-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: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" proc_do_static_key() does not consider the situation where a sysctl is only allowed to be enabled and cannot be disabled under certain circumstances since it set "->extra1" to SYSCTL_ZERO unconditionally. This patch add the functionality to set "->extra1" accordingly. Signed-off-by: Muchun Song --- kernel/sysctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 770d5f7c7ae4..1e89c3e428ad 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -1638,7 +1638,7 @@ int proc_do_static_key(struct ctl_table *table, int w= rite, .data =3D &val, .maxlen =3D sizeof(val), .mode =3D table->mode, - .extra1 =3D SYSCTL_ZERO, + .extra1 =3D table->extra1 =3D=3D SYSCTL_ONE ? 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Rebooting usually takes a long time. Add a sysctl to enable or disable the feature at runtime without rebooting. Disabling requires there is no any optimized HugeTLB page in the system. If you fail to disable it, you can set "nr_hugepages" to 0 and then retry. Signed-off-by: Muchun Song --- Documentation/admin-guide/sysctl/vm.rst | 14 +++++ include/linux/memory_hotplug.h | 9 +++ mm/hugetlb_vmemmap.c | 101 +++++++++++++++++++++++++---= ---- mm/hugetlb_vmemmap.h | 4 +- mm/memory_hotplug.c | 7 +-- 5 files changed, 108 insertions(+), 27 deletions(-) diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-= guide/sysctl/vm.rst index f4804ce37c58..9e0e153ed935 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -561,6 +561,20 @@ Change the minimum size of the hugepage pool. See Documentation/admin-guide/mm/hugetlbpage.rst =20 =20 +hugetlb_free_vmemmap +=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D + +Enable (set to 1) or disable (set to 0) the feature of optimizing vmemmap +pages associated with each HugeTLB page. Once true, the vmemmap pages of +subsequent allocation of HugeTLB pages from buddy system will be optimized, +whereas already allocated HugeTLB pages will not be optimized. If you fail +to disable this feature, you can set "nr_hugepages" to 0 and then retry +since it is only allowed to be disabled after there is no any optimized +HugeTLB page in the system. + +See Documentation/admin-guide/mm/hugetlbpage.rst + + nr_hugepages_mempolicy =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =20 diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h index 1ce6f8044f1e..9b015b254e86 100644 --- a/include/linux/memory_hotplug.h +++ b/include/linux/memory_hotplug.h @@ -348,4 +348,13 @@ void arch_remove_linear_mapping(u64 start, u64 size); extern bool mhp_supports_memmap_on_memory(unsigned long size); #endif /* CONFIG_MEMORY_HOTPLUG */ =20 +#ifdef CONFIG_MHP_MEMMAP_ON_MEMORY +bool mhp_memmap_on_memory(void); +#else +static inline bool mhp_memmap_on_memory(void) +{ + return false; +} +#endif + #endif /* __LINUX_MEMORY_HOTPLUG_H */ diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 951cf83010c7..5df41b148e79 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -176,6 +176,7 @@ */ #define pr_fmt(fmt) "HugeTLB: " fmt =20 +#include #include "hugetlb_vmemmap.h" =20 #ifdef STRUCT_PAGE_SIZE_IS_POWER_OF_2 @@ -193,6 +194,10 @@ DEFINE_STATIC_KEY_MAYBE(CONFIG_HUGETLB_PAGE_FREE_VMEMM= AP_DEFAULT_ON, hugetlb_free_vmemmap_enabled_key); EXPORT_SYMBOL(hugetlb_free_vmemmap_enabled_key); =20 +/* How many HugeTLB pages with vmemmap pages optimized. */ +static atomic_long_t optimized_pages =3D ATOMIC_LONG_INIT(0); +static DECLARE_RWSEM(sysctl_rwsem); + static int __init early_hugetlb_free_vmemmap_param(char *buf) { if (!buf) @@ -209,11 +214,6 @@ static int __init early_hugetlb_free_vmemmap_param(cha= r *buf) } early_param("hugetlb_free_vmemmap", early_hugetlb_free_vmemmap_param); =20 -static inline unsigned long free_vmemmap_pages_size_per_hpage(struct hstat= e *h) -{ - return (unsigned long)free_vmemmap_pages_per_hpage(h) << PAGE_SHIFT; -} - /* * Previously discarded vmemmap pages will be allocated and remapping * after this function returns zero. @@ -222,14 +222,18 @@ int alloc_huge_page_vmemmap(struct hstate *h, struct = page *head) { int ret; unsigned long vmemmap_addr =3D (unsigned long)head; - unsigned long vmemmap_end, vmemmap_reuse; + unsigned long vmemmap_end, vmemmap_reuse, vmemmap_pages; =20 if (!HPageVmemmapOptimized(head)) return 0; =20 - vmemmap_addr +=3D RESERVE_VMEMMAP_SIZE; - vmemmap_end =3D vmemmap_addr + free_vmemmap_pages_size_per_hpage(h); - vmemmap_reuse =3D vmemmap_addr - PAGE_SIZE; + vmemmap_addr +=3D RESERVE_VMEMMAP_SIZE; + vmemmap_pages =3D free_vmemmap_pages_per_hpage(h); + vmemmap_end =3D vmemmap_addr + (vmemmap_pages << PAGE_SHIFT); + vmemmap_reuse =3D vmemmap_addr - PAGE_SIZE; + + VM_BUG_ON_PAGE(!vmemmap_pages, head); + /* * The pages which the vmemmap virtual address range [@vmemmap_addr, * @vmemmap_end) are mapped to are freed to the buddy allocator, and @@ -239,8 +243,14 @@ int alloc_huge_page_vmemmap(struct hstate *h, struct p= age *head) */ ret =3D vmemmap_remap_alloc(vmemmap_addr, vmemmap_end, vmemmap_reuse, GFP_KERNEL | __GFP_NORETRY | __GFP_THISNODE); - if (!ret) + if (!ret) { ClearHPageVmemmapOptimized(head); + /* + * Paired with acquire semantic in + * hugetlb_free_vmemmap_handler(). + */ + atomic_long_dec_return_release(&optimized_pages); + } =20 return ret; } @@ -248,22 +258,28 @@ int alloc_huge_page_vmemmap(struct hstate *h, struct = page *head) void free_huge_page_vmemmap(struct hstate *h, struct page *head) { unsigned long vmemmap_addr =3D (unsigned long)head; - unsigned long vmemmap_end, vmemmap_reuse; + unsigned long vmemmap_end, vmemmap_reuse, vmemmap_pages; =20 - if (!free_vmemmap_pages_per_hpage(h)) - return; + down_read(&sysctl_rwsem); + vmemmap_pages =3D free_vmemmap_pages_per_hpage(h); + if (!vmemmap_pages) + goto out; =20 - vmemmap_addr +=3D RESERVE_VMEMMAP_SIZE; - vmemmap_end =3D vmemmap_addr + free_vmemmap_pages_size_per_hpage(h); - vmemmap_reuse =3D vmemmap_addr - PAGE_SIZE; + vmemmap_addr +=3D RESERVE_VMEMMAP_SIZE; + vmemmap_end =3D vmemmap_addr + (vmemmap_pages << PAGE_SHIFT); + vmemmap_reuse =3D vmemmap_addr - PAGE_SIZE; =20 /* * Remap the vmemmap virtual address range [@vmemmap_addr, @vmemmap_end) * to the page which @vmemmap_reuse is mapped to, then free the pages * which the range [@vmemmap_addr, @vmemmap_end] is mapped to. */ - if (!vmemmap_remap_free(vmemmap_addr, vmemmap_end, vmemmap_reuse)) + if (!vmemmap_remap_free(vmemmap_addr, vmemmap_end, vmemmap_reuse)) { SetHPageVmemmapOptimized(head); + atomic_long_inc(&optimized_pages); + } +out: + up_read(&sysctl_rwsem); } =20 void __init hugetlb_vmemmap_init(struct hstate *h) @@ -279,9 +295,6 @@ void __init hugetlb_vmemmap_init(struct hstate *h) BUILD_BUG_ON(__NR_USED_SUBPAGE >=3D RESERVE_VMEMMAP_SIZE / sizeof(struct page)); =20 - if (!hugetlb_free_vmemmap_enabled()) - return; - vmemmap_pages =3D (nr_pages * sizeof(struct page)) >> PAGE_SHIFT; /* * The head page is not to be freed to buddy allocator, the other tail @@ -297,4 +310,52 @@ 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); } + +static int hugetlb_free_vmemmap_handler(struct ctl_table *table, int write, + void *buffer, size_t *length, + loff_t *ppos) +{ + int ret; + + down_write(&sysctl_rwsem); + /* + * Cannot be disabled when there is at lease one optimized + * HugeTLB in the system. + * + * The acquire semantic is paired with release semantic in + * alloc_huge_page_vmemmap(). If we saw the @optimized_pages + * with 0, all the operations of vmemmap pages remapping from + * alloc_huge_page_vmemmap() are visible too so that we can + * safely disable static key. + */ + table->extra1 =3D atomic_long_read_acquire(&optimized_pages) ? + SYSCTL_ONE : SYSCTL_ZERO; + ret =3D proc_do_static_key(table, write, buffer, length, ppos); + up_write(&sysctl_rwsem); + + return ret; +} + +static struct ctl_table hugetlb_vmemmap_sysctls[] =3D { + { + .procname =3D "hugetlb_free_vmemmap", + .data =3D &hugetlb_free_vmemmap_enabled_key.key, + .mode =3D 0644, + .proc_handler =3D hugetlb_free_vmemmap_handler, + }, + { } +}; + +static __init int hugetlb_vmemmap_sysctls_init(void) +{ + /* + * The vmemmap pages cannot be optimized if + * "memory_hotplug.memmap_on_memory" is enabled. + */ + if (!mhp_memmap_on_memory()) + register_sysctl_init("vm", hugetlb_vmemmap_sysctls); + + return 0; +} +late_initcall(hugetlb_vmemmap_sysctls_init); #endif /* STRUCT_PAGE_SIZE_IS_POWER_OF_2 */ diff --git a/mm/hugetlb_vmemmap.h b/mm/hugetlb_vmemmap.h index b137fd8b6ba4..89cd85fb0d26 100644 --- a/mm/hugetlb_vmemmap.h +++ b/mm/hugetlb_vmemmap.h @@ -21,7 +21,9 @@ void hugetlb_vmemmap_init(struct hstate *h); */ static inline unsigned int free_vmemmap_pages_per_hpage(struct hstate *h) { - return h->nr_free_vmemmap_pages; + if (hugetlb_free_vmemmap_enabled()) + return h->nr_free_vmemmap_pages; + return 0; } #else static inline int alloc_huge_page_vmemmap(struct hstate *h, struct page *h= ead) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index da594b382829..793c04cfe46f 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -63,15 +63,10 @@ static bool memmap_on_memory __ro_after_init; module_param_cb(memmap_on_memory, &memmap_on_memory_ops, &memmap_on_memory= , 0444); MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hot= plug"); =20 -static inline bool mhp_memmap_on_memory(void) +bool mhp_memmap_on_memory(void) { return memmap_on_memory; } -#else -static inline bool mhp_memmap_on_memory(void) -{ - return false; -} #endif =20 enum { --=20 2.11.0