From patchwork Tue Apr 18 15:28:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 674881 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 84868C77B75 for ; Tue, 18 Apr 2023 15:29:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231273AbjDRP3s (ORCPT ); Tue, 18 Apr 2023 11:29:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45706 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230423AbjDRP3r (ORCPT ); Tue, 18 Apr 2023 11:29:47 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DC3BF9 for ; Tue, 18 Apr 2023 08:29:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1681831741; 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=lecfMikStSmpt+Q0WpS+JI6gz8j1FT0LsSw/UhC5P0k=; b=OkkSEgXsTuDlz5DR+jTr9WAMUi26Q6+Wsxg7WDxo20kYqf/GUuvFDkG/hvS84gQ1XS9vD9 OL6yMQqASWv4YnQ8ivGjqIZVdBQknYszlVY6qx/kqe0E12yNWXIYKUpYLmZQWNWXWhU1T6 mk1rF6E9/SCfFe9eQEeO7sT5esUDXAE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-637-58a_-S71MqC04QAAf1VC5A-1; Tue, 18 Apr 2023 11:28:58 -0400 X-MC-Unique: 58a_-S71MqC04QAAf1VC5A-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 78A5588905A; Tue, 18 Apr 2023 15:28:57 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.194.149]) by smtp.corp.redhat.com (Postfix) with ESMTP id 5EE7914171B8; Tue, 18 Apr 2023 15:28:54 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-s390@vger.kernel.org, linux-kselftest@vger.kernel.org, David Hildenbrand , Andrew Morton , Stefan Roesch , Rik van Riel , Johannes Weiner , Michal Hocko , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , Heiko Carstens , Vasily Gorbik , Sven Schnelle , Shuah Khan Subject: [PATCH v1 1/3] mm/ksm: unmerge and clear VM_MERGEABLE when setting PR_SET_MEMORY_MERGE=0 Date: Tue, 18 Apr 2023 17:28:47 +0200 Message-Id: <20230418152849.505124-2-david@redhat.com> In-Reply-To: <20230418152849.505124-1-david@redhat.com> References: <20230418051342.1919757-1-shr@devkernel.io> <20230418152849.505124-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Let's unmerge any KSM pages when setting PR_SET_MEMORY_MERGE=0, and clear the VM_MERGEABLE flag from all VMAs -- just like KSM would. Of course, only do that if we previously set PR_SET_MEMORY_MERGE=1. Signed-off-by: David Hildenbrand Acked-by: Stefan Roesch --- include/linux/ksm.h | 1 + kernel/sys.c | 7 +------ mm/ksm.c | 47 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 49 insertions(+), 6 deletions(-) diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 590934bdddcf..7108bc65dc2a 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -21,6 +21,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start, void ksm_add_vma(struct vm_area_struct *vma); int ksm_enable_merge_any(struct mm_struct *mm); +int ksm_disable_merge_any(struct mm_struct *mm); int __ksm_enter(struct mm_struct *mm); void __ksm_exit(struct mm_struct *mm); diff --git a/kernel/sys.c b/kernel/sys.c index 72cdb16e2636..3436376667d7 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2698,12 +2698,7 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, if (arg2) { error = ksm_enable_merge_any(me->mm); } else { - /* - * TODO: we might want disable KSM on all VMAs and - * trigger unsharing to completely disable KSM. - */ - clear_bit(MMF_VM_MERGE_ANY, &me->mm->flags); - error = 0; + error = ksm_disable_merge_any(me->mm); } mmap_write_unlock(me->mm); break; diff --git a/mm/ksm.c b/mm/ksm.c index a959e8925413..813f7fbc1832 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2520,6 +2520,22 @@ static void __ksm_add_vma(struct vm_area_struct *vma) vm_flags_set(vma, VM_MERGEABLE); } +static int __ksm_del_vma(struct vm_area_struct *vma) +{ + int err; + + if (!(vma->vm_flags & VM_MERGEABLE)) + return 0; + + if (vma->anon_vma) { + err = unmerge_ksm_pages(vma, vma->vm_start, vma->vm_end); + if (err) + return err; + } + + vm_flags_clear(vma, VM_MERGEABLE); + return 0; +} /** * ksm_add_vma - Mark vma as mergeable if compatible * @@ -2542,6 +2558,20 @@ static void ksm_add_vmas(struct mm_struct *mm) __ksm_add_vma(vma); } +static int ksm_del_vmas(struct mm_struct *mm) +{ + struct vm_area_struct *vma; + int err; + + VMA_ITERATOR(vmi, mm, 0); + for_each_vma(vmi, vma) { + err = __ksm_del_vma(vma); + if (err) + return err; + } + return 0; +} + /** * ksm_enable_merge_any - Add mm to mm ksm list and enable merging on all * compatible VMA's @@ -2569,6 +2599,23 @@ int ksm_enable_merge_any(struct mm_struct *mm) return 0; } +int ksm_disable_merge_any(struct mm_struct *mm) +{ + int err; + + if (!test_bit(MMF_VM_MERGE_ANY, &mm->flags)) + return 0; + + err = ksm_del_vmas(mm); + if (err) { + ksm_add_vmas(mm); + return err; + } + + clear_bit(MMF_VM_MERGE_ANY, &mm->flags); + return 0; +} + int ksm_madvise(struct vm_area_struct *vma, unsigned long start, unsigned long end, int advice, unsigned long *vm_flags) {