From patchwork Fri Sep 30 14:19:24 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Hildenbrand X-Patchwork-Id: 12995501 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 ED7F9C4332F for ; Fri, 30 Sep 2022 14:20:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231839AbiI3OT6 (ORCPT ); Fri, 30 Sep 2022 10:19:58 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38826 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231845AbiI3OTy (ORCPT ); Fri, 30 Sep 2022 10:19:54 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ECCF7481F5 for ; Fri, 30 Sep 2022 07:19:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1664547589; 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; bh=eksXkTT4hqG/3veGcAG1lXhndJ/4JYD7d1ML/eQwqI0=; b=ROt3wsSubHEuqDx+EdV8tVJalSUbNKXaXEMWudfairjOT/Qz7Ki6DlhjlGj4LxWFMQmrD7 GU9b6d4niqsbbKNTqC0IXz68NYOr9gBI+soR34E9jWqN5Wc2wg757GWiWQFyC3f33oSej4 1tkZg20Z6AeptN6bhJ7RdVOXdFfwOyc= 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-264-WVKMxLXMOA-eW7lYh1eiHA-1; Fri, 30 Sep 2022 10:19:46 -0400 X-MC-Unique: WVKMxLXMOA-eW7lYh1eiHA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.rdu2.redhat.com [10.11.54.3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 765C3101A528; Fri, 30 Sep 2022 14:19:45 +0000 (UTC) Received: from t480s.redhat.com (unknown [10.39.194.187]) by smtp.corp.redhat.com (Postfix) with ESMTP id E6DCF1121315; Fri, 30 Sep 2022 14:19:32 +0000 (UTC) From: David Hildenbrand To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, David Hildenbrand , Andrew Morton , Shuah Khan , Hugh Dickins , Vlastimil Babka , Peter Xu , Andrea Arcangeli , "Matthew Wilcox (Oracle)" , Jason Gunthorpe , John Hubbard Subject: [PATCH v1 0/7] mm/ksm: break_ksm() cleanups and fixes Date: Fri, 30 Sep 2022 16:19:24 +0200 Message-Id: <20220930141931.174362-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org This series cleans up and fixes break_ksm(). In summary, we no longer use fake write faults to break COW but instead FAULT_FLAG_UNSHARE. Further, we move away from using follow_page() [that we can hopefully remove completely at one point] and use new walk_page_range_vma() instead. Fortunately, we can get rid of VM_FAULT_WRITE and FOLL_MIGRATION in common code now. Add a selftest to measure MADV_UNMERGEABLE performance. In my setup (AMD Ryzen 9 3900X), running the KSM selftest to test unmerge performance on 2 GiB (taskset 0x8 ./ksm_tests -D -s 2048), this results in a performance degradation of ~8% -- 9% (old: ~5250 MiB/s, new: ~4800 MiB/s). I don't think we particularly care for now, but it's good to be aware of the implication. Cc: Andrew Morton Cc: Shuah Khan Cc: Hugh Dickins Cc: Vlastimil Babka Cc: Peter Xu Cc: Andrea Arcangeli Cc: "Matthew Wilcox (Oracle)" Cc: Jason Gunthorpe Cc: John Hubbard David Hildenbrand (7): selftests/vm: add test to measure MADV_UNMERGEABLE performance mm/ksm: simplify break_ksm() to not rely on VM_FAULT_WRITE mm: remove VM_FAULT_WRITE mm/ksm: fix KSM COW breaking with userfaultfd-wp via FAULT_FLAG_UNSHARE mm/pagewalk: add walk_page_range_vma() mm/ksm: convert break_ksm() to use walk_page_range_vma() mm/gup: remove FOLL_MIGRATION include/linux/mm.h | 1 - include/linux/mm_types.h | 3 - include/linux/pagewalk.h | 3 + mm/gup.c | 55 ++----------- mm/huge_memory.c | 2 +- mm/ksm.c | 103 +++++++++++++++++++------ mm/memory.c | 9 +-- mm/pagewalk.c | 27 +++++++ tools/testing/selftests/vm/ksm_tests.c | 76 +++++++++++++++++- 9 files changed, 192 insertions(+), 87 deletions(-)