From patchwork Thu Feb 25 02:14:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 12103099 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-21.2 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B9592C433E9 for ; Thu, 25 Feb 2021 02:15:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7021164F03 for ; Thu, 25 Feb 2021 02:15:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235942AbhBYCPf (ORCPT ); Wed, 24 Feb 2021 21:15:35 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37592 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235527AbhBYCP1 (ORCPT ); Wed, 24 Feb 2021 21:15:27 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75B0DC061756 for ; Wed, 24 Feb 2021 18:14:41 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id f127so4368186ybf.12 for ; Wed, 24 Feb 2021 18:14:41 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=sender:date:message-id:mime-version:subject:from:to:cc; bh=d7qjpU8XKEfBqlMiCyPh8nFPbvWh1eJ63+H3QFuie5Y=; b=UMLqTstxNUBx26sg6GLN6yLQPAjd2tgC7PtHCBbHKD4iSU1KIibkTuyxM4iqtkGaCg Ir5emR92f/9DRcZXi+gQ01lXg0qFQy1IjrPYgogIJyIzp/E/dzz+RuR4G4xHh4rpFSjE KxRt4gnRJ0ElbEoeuEI1i3RJ0Svq53VVxRgipBXKZ7oUcdEIDkZjEmqnhG9Z4/by8xpb uhmiPiMYSHUi2h34aYQdi73+ZbPCms3CJAaw/DEiQB5utN3e7pP0npwWSMuGcu0Q1DRK IL8TaM0PNMCbmKdnu6yJ9/5IVHqXEzbuNYDLaEagmMRZl+VZ3N6UNqlAJRaP1ZOfpxl3 RCPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:message-id:mime-version:subject:from :to:cc; bh=d7qjpU8XKEfBqlMiCyPh8nFPbvWh1eJ63+H3QFuie5Y=; b=g0hdyqqy7hQHRxnnRk+i8RhrOFiqhtCHq2gNj+H2R8HCGweHCgusDjbQLN9T+BeIrP 1D18Me7GO6llzIrCHzU7qTxUQvPSTim0clP22fqcxkFwVVJI9PWwqWB03xKGL8sBAmr8 LBH56ijp5VXVWwMJxBOFHnURrp9nhwlZ4E/N4PP8TK+BE7U77M6iMu3ZwBSk8kGN5NwK D4tbIkAgAZseuORQnETzkyitvskeI54iVaGy5PJVubYBqLLGj2qyKQXeGzmaF0NOZuGx Glz9yJWCMbSbKGzEQkC8Ul5edAEDwDwgtLXQ6qgK8u/xgwKMFVwcs/3jYudJtclf6gVo CLsA== X-Gm-Message-State: AOAM532Cd9Hv13CBlshOSiahJkzqXJmjqxRekDjcnO7GxMnPzka9gYse mrQtE1XBtc2N+0fsCL9nsyTTiPwE/BDtQzJ8GYYj X-Google-Smtp-Source: ABdhPJw98ig0Yji2QsABXFSreCF+ogXsubw5CFDtC6GaaoOwFYEUFPOQp0YULt8aO2A/kWa9cWqMeli63FZEp52R2m/7 Sender: "axelrasmussen via sendgmr" X-Received: from ajr0.svl.corp.google.com ([2620:15c:2cd:203:a5fd:f848:2fdf:4651]) (user=axelrasmussen job=sendgmr) by 2002:a25:8112:: with SMTP id o18mr902059ybk.208.1614219280483; Wed, 24 Feb 2021 18:14:40 -0800 (PST) Date: Wed, 24 Feb 2021 18:14:15 -0800 Message-Id: <20210225021420.2290912-1-axelrasmussen@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.30.0.617.g56c4b15f3c-goog Subject: [PATCH 0/5] userfaultfd: support minor fault handling for shmem From: Axel Rasmussen To: Alexander Viro , Andrea Arcangeli , Andrew Morton , Hugh Dickins , Jerome Glisse , Joe Perches , Lokesh Gidra , Mike Rapoport , Peter Xu , Shaohua Li , Shuah Khan , Wang Qing Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Axel Rasmussen , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Michel Lespinasse , Mina Almasry , Oliver Upton Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org Base ==== This series is based on top of my series which adds minor fault handling for hugetlbfs [1]. (And, therefore, it is based on linux-next/akpm and Peter Xu's series for disabling huge pmd sharing as well.) [1] https://lore.kernel.org/patchwork/cover/1384095/ Overview ======== See my original series linked above for a detailed overview of minor fault handling in general. The feature in this series works exactly like the hugetblfs version (from userspace's perspective). I'm sending this as a separate series because: - The original minor fault handling series has been through several rounds of review and seems close to being merged, so it seems reasonable to start looking at this next step. - shmem is different enough that this series may require some additional work before it's ready, and I don't want to delay the original series unnecessarily by bundling them together. Use Case ======== In some cases it is useful to have VM memory backed by tmpfs instead of hugetlbfs. So, this feature will be used to support the same VM live migration use case described in my original series. Additionally, Android folks (Lokesh Gidra ) hope to optimize the Android JVM garbage collector using this feature (a paper describing a somewhat similar approach: https://arxiv.org/pdf/1902.04738.pdf). Axel Rasmussen (5): userfaultfd: support minor fault handling for shmem userfaultfd/selftests: use memfd_create for shmem test type userfaultfd/selftests: create alias mappings in the shmem test userfaultfd/selftests: reinitialize test context in each test userfaultfd/selftests: exercise minor fault handling shmem support fs/userfaultfd.c | 6 +- include/linux/shmem_fs.h | 26 +- include/uapi/linux/userfaultfd.h | 4 +- mm/memory.c | 8 +- mm/shmem.c | 88 +++---- mm/userfaultfd.c | 27 +- tools/testing/selftests/vm/userfaultfd.c | 322 +++++++++++++++-------- 7 files changed, 293 insertions(+), 188 deletions(-) --- 2.30.0.617.g56c4b15f3c-goog