From mboxrd@z Thu Jan 1 00:00:00 1970 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=-14.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,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 63121C3A5A6 for ; Mon, 26 Aug 2019 23:32:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 265962053B for ; Mon, 26 Aug 2019 23:32:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="CY1aI8s6" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 265962053B Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id AB03F6B028B; Mon, 26 Aug 2019 19:32:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A60AC6B028C; Mon, 26 Aug 2019 19:32:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 977B56B028D; Mon, 26 Aug 2019 19:32:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0230.hostedemail.com [216.40.44.230]) by kanga.kvack.org (Postfix) with ESMTP id 7855A6B028B for ; Mon, 26 Aug 2019 19:32:50 -0400 (EDT) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 0EB34181AC9B4 for ; Mon, 26 Aug 2019 23:32:50 +0000 (UTC) X-FDA: 75866181300.29.place57_35c4ea1a27911 X-HE-Tag: place57_35c4ea1a27911 X-Filterd-Recvd-Size: 8064 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Mon, 26 Aug 2019 23:32:49 +0000 (UTC) Received: by mail-pf1-f202.google.com with SMTP id 191so13255372pfy.20 for ; Mon, 26 Aug 2019 16:32:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=ElPLhkujITMw+6kOZxdN4egPf1l2LHGwTUiYDYEp8fM=; b=CY1aI8s69o9YGJ6K0vFmmYLyZzVcf7onXN3mweVqR4ZVSJ+5HLlMO+q+W9vvWtb6vR z2AkrdPcZcVdVlYEGdkDSHBbkFBq51Ovx3UJg1LQ4+Ycem0XA2703fLioTfaokEhnbA8 syXgP8odCYCcmUvJVe8bSrlTzfih3jZ+pCyEfFf7ALVFgfr+A50/JcYr33g1gZ3yJUT5 pRNe4gRSKcKE0AUplOuw3dNWsmY4BpIby3TVjfxq9tasyxAMh4DsD8kRtius50dvXEUd WiEEXxDZY+WKTX2pe0nvVtRh9/M/BgviA6AIcxL76YM9EiRGO7Bg+4aetvVdl6UVPQmN oNUw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=ElPLhkujITMw+6kOZxdN4egPf1l2LHGwTUiYDYEp8fM=; b=m93Vn56P95fKhzWgNzEfqi/dg01CFmmyI+DnwY8DtdyKXU51sg5x3Xd8tkmz9iGrsA /YR5Laqunvi4lzyspYsfnFxH1qj6FqCOV4iB5UIEAteHe4W770I408CKdOf151f1kA51 Xug2PAihohKQE04VGjPfaveykbAkCsAniCLbPrmDaIXTO+gHfN9nELdIUoBrRwiTP+5l qqTR+NF7CipZkOcBlRyNZnuBDb7skRrgqQqhYBPmrqtOGz699xkhxi3nDNgz4QmlQuQH 18z9mMdmg5lstQGKARdki9pBu8V2MpKY5pLTTDhK0HAgefNwWzHB0j/vD2Or2M/tMKSt hlMA== X-Gm-Message-State: APjAAAVqBnkEGAS1k3ovba86zd86T18VTui9cQ00d6wla1P2Xk1NDn0F 4nQgUvk1w7Eh0P1sRIc+iO8RfAQeIH8yjXtlDA== X-Google-Smtp-Source: APXvYqy4f+EGhY8DA4EciaGoRIk8Vvo11a6sPW9cP6RYxJwTxvvZimzDTPUT71oa4DyVBmPcrm+fw+qhfDPlEnv/bQ== X-Received: by 2002:a63:c013:: with SMTP id h19mr18714986pgg.108.1566862367741; Mon, 26 Aug 2019 16:32:47 -0700 (PDT) Date: Mon, 26 Aug 2019 16:32:34 -0700 Message-Id: <20190826233240.11524-1-almasrymina@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.23.0.187.g17f5b7556c-goog Subject: [PATCH v3 0/6] hugetlb_cgroup: Add hugetlb_cgroup reservation limits From: Mina Almasry To: mike.kravetz@oracle.com Cc: shuah@kernel.org, almasrymina@google.com, rientjes@google.com, shakeelb@google.com, gthelen@google.com, akpm@linux-foundation.org, khalid.aziz@oracle.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, cgroups@vger.kernel.org, aneesh.kumar@linux.vnet.ibm.com, mkoutny@suse.com Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Problem: Currently tasks attempting to allocate more hugetlb memory than is available get a failure at mmap/shmget time. This is thanks to Hugetlbfs Reservations [1]. However, if a task attempts to allocate hugetlb memory only more than its hugetlb_cgroup limit allows, the kernel will allow the mmap/shmget call, but will SIGBUS the task when it attempts to fault the memory in. We have developers interested in using hugetlb_cgroups, and they have expressed dissatisfaction regarding this behavior. We'd like to improve this behavior such that tasks violating the hugetlb_cgroup limits get an error on mmap/shmget time, rather than getting SIGBUS'd when they try to fault the excess memory in. The underlying problem is that today's hugetlb_cgroup accounting happens at hugetlb memory *fault* time, rather than at *reservation* time. Thus, enforcing the hugetlb_cgroup limit only happens at fault time, and the offending task gets SIGBUS'd. Proposed Solution: A new page counter named hugetlb.xMB.reservation_[limit|usage]_in_bytes. This counter has slightly different semantics than hugetlb.xMB.[limit|usage]_in_bytes: - While usage_in_bytes tracks all *faulted* hugetlb memory, reservation_usage_in_bytes tracks all *reserved* hugetlb memory. - If a task attempts to reserve more memory than limit_in_bytes allows, the kernel will allow it to do so. But if a task attempts to reserve more memory than reservation_limit_in_bytes, the kernel will fail this reservation. This proposal is implemented in this patch, with tests to verify functionality and show the usage. Alternatives considered: 1. A new cgroup, instead of only a new page_counter attached to the existing hugetlb_cgroup. Adding a new cgroup seemed like a lot of code duplication with hugetlb_cgroup. Keeping hugetlb related page counters under hugetlb_cgroup seemed cleaner as well. 2. Instead of adding a new counter, we considered adding a sysctl that modifies the behavior of hugetlb.xMB.[limit|usage]_in_bytes, to do accounting at reservation time rather than fault time. Adding a new page_counter seems better as userspace could, if it wants, choose to enforce different cgroups differently: one via limit_in_bytes, and another via reservation_limit_in_bytes. This could be very useful if you're transitioning how hugetlb memory is partitioned on your system one cgroup at a time, for example. Also, someone may find usage for both limit_in_bytes and reservation_limit_in_bytes concurrently, and this approach gives them the option to do so. Caveats: 1. This support is implemented for cgroups-v1. I have not tried hugetlb_cgroups with cgroups v2, and AFAICT it's not supported yet. This is largely because we use cgroups-v1 for now. If required, I can add hugetlb_cgroup support to cgroups v2 in this patch or a follow up. 2. Most complicated bit of this patch I believe is: where to store the pointer to the hugetlb_cgroup to uncharge at unreservation time? Normally the cgroup pointers hang off the struct page. But, with hugetlb_cgroup reservations, one task can reserve a specific page and another task may fault it in (I believe), so storing the pointer in struct page is not appropriate. Proposed approach here is to store the pointer in the resv_map. See patch for details. Signed-off-by: Mina Almasry [1]: https://www.kernel.org/doc/html/latest/vm/hugetlbfs_reserv.html Changes in v3: - Addressed comments of Hillf Danton: - Added docs. - cgroup_files now uses enum. - Various readability improvements. - Addressed comments of Mike Kravetz. - region_* functions no longer coalesce file_region entries in the resv_map. - region_add() and region_chg() refactored to make them much easier to understand and remove duplicated code so this patch doesn't add too much complexity. - Refactored common functionality into helpers. Changes in v2: - Split the patch into a 5 patch series. - Fixed patch subject. Mina Almasry (6): hugetlb_cgroup: Add hugetlb_cgroup reservation counter hugetlb_cgroup: add interface for charge/uncharge hugetlb reservations hugetlb_cgroup: add reservation accounting for private mappings hugetlb_cgroup: add accounting for shared mappings hugetlb_cgroup: Add hugetlb_cgroup reservation tests hugetlb_cgroup: Add hugetlb_cgroup reservation docs .../admin-guide/cgroup-v1/hugetlb.rst | 84 ++- include/linux/hugetlb.h | 24 +- include/linux/hugetlb_cgroup.h | 19 +- mm/hugetlb.c | 493 ++++++++++++------ mm/hugetlb_cgroup.c | 187 +++++-- tools/testing/selftests/vm/.gitignore | 1 + tools/testing/selftests/vm/Makefile | 4 + .../selftests/vm/charge_reserved_hugetlb.sh | 438 ++++++++++++++++ .../selftests/vm/write_hugetlb_memory.sh | 22 + .../testing/selftests/vm/write_to_hugetlbfs.c | 252 +++++++++ 10 files changed, 1300 insertions(+), 224 deletions(-) create mode 100755 tools/testing/selftests/vm/charge_reserved_hugetlb.sh create mode 100644 tools/testing/selftests/vm/write_hugetlb_memory.sh create mode 100644 tools/testing/selftests/vm/write_to_hugetlbfs.c -- 2.23.0.187.g17f5b7556c-goog