From nobody Fri Sep 12 13:37:23 2025 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 39A4CC7EE2E for ; Tue, 13 Jun 2023 03:11:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239581AbjFMDLw (ORCPT ); Mon, 12 Jun 2023 23:11:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240437AbjFMDLH (ORCPT ); Mon, 12 Jun 2023 23:11:07 -0400 Received: from ubuntu20 (unknown [193.203.214.57]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E599189 for ; Mon, 12 Jun 2023 20:09:41 -0700 (PDT) Received: by ubuntu20 (Postfix, from userid 1003) id CF36DE22C9; Tue, 13 Jun 2023 11:09:39 +0800 (CST) From: Yang Yang To: akpm@linux-foundation.org, david@redhat.com Cc: yang.yang29@zte.com.cn, imbrenda@linux.ibm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, ran.xiaokai@zte.com.cn, xu.xin.sc@gmail.com, xu.xin16@zte.com.cn, Xuexin Jiang Subject: [PATCH RESEND v10 3/5] ksm: add ksm zero pages for each process Date: Tue, 13 Jun 2023 11:09:38 +0800 Message-Id: <20230613030938.185993-1-yang.yang29@zte.com.cn> X-Mailer: git-send-email 2.25.1 In-Reply-To: <202306131104554703428@zte.com.cn> References: <202306131104554703428@zte.com.cn> 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" From: xu xin As the number of ksm zero pages is not included in ksm_merging_pages per process when enabling use_zero_pages, it's unclear of how many actual pages are merged by KSM. To let users accurately estimate their memory demands when unsharing KSM zero-pages, it's necessary to show KSM zero- pages per process. In addition, it help users to know the actual KSM profit because KSM-placed zero pages are also benefit from KSM. since unsharing zero pages placed by KSM accurately is achieved, then tracking empty pages merging and unmerging is not a difficult thing any longer. Since we already have /proc//ksm_stat, just add the information of 'ksm_zero_pages' in it. Signed-off-by: xu xin Acked: David Hildenbrand Reviewed-by: Xiaokai Ran Reviewed-by: Yang Yang Cc: Claudio Imbrenda Cc: Xuexin Jiang --- fs/proc/base.c | 1 + include/linux/ksm.h | 8 +++++--- include/linux/mm_types.h | 9 +++++++-- mm/khugepaged.c | 2 +- mm/ksm.c | 1 + mm/memory.c | 4 ++-- 6 files changed, 17 insertions(+), 8 deletions(-) diff --git a/fs/proc/base.c b/fs/proc/base.c index 05452c3b9872..eb2e498e3b8d 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -3207,6 +3207,7 @@ static int proc_pid_ksm_stat(struct seq_file *m, stru= ct pid_namespace *ns, mm =3D get_task_mm(task); if (mm) { seq_printf(m, "ksm_rmap_items %lu\n", mm->ksm_rmap_items); + seq_printf(m, "ksm_zero_pages %lu\n", mm->ksm_zero_pages); seq_printf(m, "ksm_merging_pages %lu\n", mm->ksm_merging_pages); seq_printf(m, "ksm_process_profit %ld\n", ksm_process_profit(mm)); mmput(mm); diff --git a/include/linux/ksm.h b/include/linux/ksm.h index e80aa49009b2..c2dd786a30e1 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -35,10 +35,12 @@ void __ksm_exit(struct mm_struct *mm); =20 extern unsigned long ksm_zero_pages; =20 -static inline void ksm_might_unmap_zero_page(pte_t pte) +static inline void ksm_might_unmap_zero_page(struct mm_struct *mm, pte_t p= te) { - if (is_ksm_zero_pte(pte)) + if (is_ksm_zero_pte(pte)) { ksm_zero_pages--; + mm->ksm_zero_pages--; + } } =20 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm) @@ -109,7 +111,7 @@ static inline void ksm_exit(struct mm_struct *mm) { } =20 -static inline void ksm_might_unmap_zero_page(pte_t pte) +static inline void ksm_might_unmap_zero_page(struct mm_struct *mm, pte_t p= te) { } =20 diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 306a3d1a0fa6..14f781509812 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -777,7 +777,7 @@ struct mm_struct { #ifdef CONFIG_KSM /* * Represent how many pages of this process are involved in KSM - * merging. + * merging (not including ksm_zero_pages). */ unsigned long ksm_merging_pages; /* @@ -785,7 +785,12 @@ struct mm_struct { * including merged and not merged. */ unsigned long ksm_rmap_items; -#endif + /* + * Represent how many empty pages are merged with kernel zero + * pages when enabling KSM use_zero_pages. + */ + unsigned long ksm_zero_pages; +#endif /* CONFIG_KSM */ #ifdef CONFIG_LRU_GEN struct { /* this mm_struct is on lru_gen_mm_list */ diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 3f293e2436f3..225d98744d2e 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -712,7 +712,7 @@ static void __collapse_huge_page_copy_succeeded(pte_t *= pte, spin_lock(ptl); ptep_clear(vma->vm_mm, address, _pte); spin_unlock(ptl); - ksm_might_unmap_zero_page(pteval); + ksm_might_unmap_zero_page(vma->vm_mm, pteval); } } else { src_page =3D pte_page(pteval); diff --git a/mm/ksm.c b/mm/ksm.c index d3ed90159322..07a6fe7d7c99 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1231,6 +1231,7 @@ static int replace_page(struct vm_area_struct *vma, s= truct page *page, */ newpte =3D pte_mkdirty(pte_mkspecial(pfn_pte(page_to_pfn(kpage), vma->vm= _page_prot))); ksm_zero_pages++; + mm->ksm_zero_pages++; /* * We're replacing an anonymous page with a zero page, which is * not anonymous. We need to do proper accounting otherwise we diff --git a/mm/memory.c b/mm/memory.c index 15e6bd757eab..811a98fb403e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1416,7 +1416,7 @@ static unsigned long zap_pte_range(struct mmu_gather = *tlb, zap_install_uffd_wp_if_needed(vma, addr, pte, details, ptent); if (unlikely(!page)) { - ksm_might_unmap_zero_page(ptent); + ksm_might_unmap_zero_page(mm, ptent); continue; } =20 @@ -3122,7 +3122,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf) inc_mm_counter(mm, MM_ANONPAGES); } } else { - ksm_might_unmap_zero_page(vmf->orig_pte); + ksm_might_unmap_zero_page(mm, vmf->orig_pte); inc_mm_counter(mm, MM_ANONPAGES); } flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte)); --=20 2.15.2