From patchwork Sat Dec 24 08:20:34 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zach O'Keefe X-Patchwork-Id: 36398 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:4e01:0:0:0:0:0 with SMTP id p1csp72381wrt; Sat, 24 Dec 2022 00:51:36 -0800 (PST) X-Google-Smtp-Source: AMrXdXsKE8OYY5arixVkElDeWJPRbwcPBE//PP0pKvqjhSpY3QjYgTvYE+pSdraz4uFe3aC50v+u X-Received: by 2002:a17:902:ee13:b0:189:13df:9d86 with SMTP id z19-20020a170902ee1300b0018913df9d86mr15073629plb.14.1671871895953; Sat, 24 Dec 2022 00:51:35 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1671871895; cv=none; d=google.com; s=arc-20160816; b=P7t0OQTRRntJeNYvuT2vSbMIkh1dRMvE9yX/uLpthzLMz6Ljwz9FXNp0U6GEixXSIf BLuz+LYBLhcWLiKaeXsq8RD5/4+uw/xIA1xrZr9WojeQyIlzeBbGsXwhpLXDfxexqHgF 9urO6sCbmb/o+dqlnCHuxG3dl0yT8wzQu4q6T1kWP9rsPIo8xHNwuMBe065gdiK7tDhU /NTzd5ANmxoGnzcvCU2F4qsDKCAFNp20bwzoss0GRNe9XZz/6JpA40NJ4SCgixV/Y+sL sAG3w+C05fpkMnjv/XIEFxH3SjkaA3V6mrAOretCAUYcvGu/QHy9YbyTi2pEdMEAz0g/ opFQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:mime-version:date :dkim-signature; bh=ihTDH6jZHdlVGdscYLo+1J1fOC8tjCOiHkEMZL35An0=; b=gTC5Ed5B1ogJ37leruxl+cMm1tQl9WBIN96U+69Y/+iTO73HzHNS0FQEwVk18WMBpH GIr9AOk16XMhuyLNqe6Jb0xY14BdtmDLFINlZSlPZjs426g9DgO1vq6pu3auUhi/R2D3 UllEMJixrKQk4GVoVO3xjQ4I9w/Ta4l0J0CE3exOsv7ms2y44vIkr7XNnA8yU+RP74ep cWdCqRHXdHySJOfTfXeUxZGxLUpT8tuW7X5EzYtG3fnWV/Y654Pqrcr/Jf51qN5SSYje TDPemn9CTbzkM60fjTiCK7OT3CDFQNupnpY3FkZvclLNEnIBoRZfm5I9lgTyTH4bt3+H a8oA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=O2Rgjytv; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id q2-20020a170902edc200b0018c166e2304si5460179plk.299.2022.12.24.00.51.21; Sat, 24 Dec 2022 00:51:35 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=O2Rgjytv; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230386AbiLXIUl (ORCPT + 99 others); Sat, 24 Dec 2022 03:20:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230073AbiLXIUj (ORCPT ); Sat, 24 Dec 2022 03:20:39 -0500 Received: from mail-pf1-x449.google.com (mail-pf1-x449.google.com [IPv6:2607:f8b0:4864:20::449]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6BAFADFA2 for ; Sat, 24 Dec 2022 00:20:38 -0800 (PST) Received: by mail-pf1-x449.google.com with SMTP id k22-20020aa79736000000b0057f3577fdbaso3549972pfg.8 for ; Sat, 24 Dec 2022 00:20:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=ihTDH6jZHdlVGdscYLo+1J1fOC8tjCOiHkEMZL35An0=; b=O2RgjytvDPz+6g9CFcczLL248lQ0CKGMUUPXSrAXNh49DWEMFH6BB2Lu/8S/m1Kd7R Bbsz01ZiRT223Syp1Eh8kai1+ObucV/135HjfhH/GAAJY7X6m0MNIIp+V8920RBGR8RY ft42nde+5+lSZI87XCDPY+KcgYaQE4nB4d1mZWFmGojxerVBeU6Wi9EA+5lLrc0hezdj rTwNYEsX9FdvJGxM1T5juuxMYPYcEZ4eDajArurOQ2qOcm79cw1AWS9I0uiItkwStEHd aYL4JlQ+/BpySpoV/dNjsTPOdw2ifprcV9CU3S2243eAiX/YA4qE6bWLcOQhevfRonxY BV3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=ihTDH6jZHdlVGdscYLo+1J1fOC8tjCOiHkEMZL35An0=; b=EexG6WmFFnxgFeOfM6h10HPJuyvpZqdCmrA1kcQuv171cR7PhwyQuWrJAtqOp0uC86 I/1FeD5cU3ZJfJLY3HrHeyy3GZxj6sg6qHb17mMGr5kXpxAEyvg1n8X/4GQbDpG6xoS3 5Xi30kAJrHuIkYP+veIFgWpOUAMwhE0Q2QJNykpxY8bWam3YN7PIkFvvkM1wDJtyfHol MjeT7WavxUpqYxTFf+8RCq8H6qc/3+JjQ9awXN6qSMQS/sA+EddEleXwkjODQdpWI6Cf ueAib4oOesbd6ImjEVlMX8/OpKcpnAFoUBKfbPsia1qguQaXBYGMANx+69FpJ5Xx7C9Y xszw== X-Gm-Message-State: AFqh2kprdrSkndIV8AH5O0J/e5Yn0JObmDZ9/nCfqoEMheEICEcusS3i xkHlbPQ6zPabh9C0pn53tGk7nXPlqcxc X-Received: from zokeefe3.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:1b6]) (user=zokeefe job=sendgmr) by 2002:a17:90b:3015:b0:219:c8d5:27d7 with SMTP id hg21-20020a17090b301500b00219c8d527d7mr1200309pjb.141.1671870037941; Sat, 24 Dec 2022 00:20:37 -0800 (PST) Date: Sat, 24 Dec 2022 00:20:34 -0800 Mime-Version: 1.0 X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20221224082035.3197140-1-zokeefe@google.com> Subject: [PATCH v3 1/2] mm/MADV_COLLAPSE: don't expand collapse when vm_end is past requested end From: "Zach O'Keefe" To: linux-mm@kvack.org Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , Yang Shi , "Zach O'Keefe" X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1753082750891856516?= X-GMAIL-MSGID: =?utf-8?q?1753084745088189915?= MADV_COLLAPSE acts on one hugepage-aligned/sized region at a time, until it has collapsed all eligible memory contained within the bounds supplied by the user. At the top of each hugepage iteration we (re)lock mmap_lock and (re)validate the VMA for eligibility and update variables that might have changed while mmap_lock was dropped. One thing that might occur, is that the VMA could be resized, and as such, we refetch vma->vm_end to make sure we don't collapse past the end of the VMA's new end. However, it's possible that when refetching vma>vm_end that we expand the region acted on by MADV_COLLAPSE if vma->vm_end is greater than size+len supplied by the user. The consequence here is that we may attempt to collapse more memory than requested, possibly yielding either "too much success" or "false failure" user-visible results. An example of the former is if we MADV_COLLAPSE the first 4MiB of a 2TiB mmap()'d file, the incorrect refetch would cause the operation to block for much longer than anticipated as we attempt to collapse the entire TiB region. An example of the latter is that applying MADV_COLLPSE to a 4MiB file mapped to the start of a 6MiB VMA will successfully collapse the first 4MiB, then incorrectly attempt to collapse the last hugepage-aligned/sized region -- fail (since readahead/page cache lookup will fail) -- and report a failure to the user. Don't expand the acted-on region when refetching vma->vm_end. Fixes: 4d24de9425f7 ("mm: MADV_COLLAPSE: refetch vm_end after reacquiring mmap_lock") Reported-by: Hugh Dickins Signed-off-by: Zach O'Keefe Cc: Yang Shi Cc: stable@vger.kernel.org --- v2->v3: Add 'Cc: stable@vger.kernel.org' as per stable-kernel-rules. v1->v2: Updated changelog to make clear what user-visible issues this patch addresses, as well makes the case for backporting (Andrew Morton). While there aren't any stability risks, without this patch there exist trivial examples where MADV_COLLAPSE won't work; as such, this should be backported to stable 6.1.X to make MADV_COLLAPSE dependable in such cases. v1: https://lore.kernel.org/linux-mm/CAAa6QmRx_b2UCJWE2XZ3=3c3-_N3R4cDGX6Wm4OT7qhFC6U_SQ@mail.gmail.com/T/#m6c91da3cdbd9b1d1ebb29d415962deb158a2c658 --- mm/khugepaged.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 5cb401aa2b9d..b4d2ec0a94ed 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2649,7 +2649,7 @@ int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev, goto out_nolock; } - hend = vma->vm_end & HPAGE_PMD_MASK; + hend = min(hend, vma->vm_end & HPAGE_PMD_MASK); } mmap_assert_locked(mm); memset(cc->node_load, 0, sizeof(cc->node_load)); From patchwork Sat Dec 24 08:20:35 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zach O'Keefe X-Patchwork-Id: 36397 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:4e01:0:0:0:0:0 with SMTP id p1csp69976wrt; Sat, 24 Dec 2022 00:40:52 -0800 (PST) X-Google-Smtp-Source: AMrXdXtDWxVxcON2obDcmo0wmSf4YRzj8qCBRTw25cG55OrQhMlKoxwyRheAOafo8I8ZBIXU3ffR X-Received: by 2002:a17:902:ba93:b0:192:4a70:3f57 with SMTP id k19-20020a170902ba9300b001924a703f57mr11024636pls.8.1671871251926; Sat, 24 Dec 2022 00:40:51 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1671871251; cv=none; d=google.com; s=arc-20160816; b=K51foGESIPF2GU6lwb0mMX3Jd9AeWZtSqf2uzGRRnjU2OXxiJhUyI/yvrCs50edLmn zELmA2PSVEPHXjWbj6N8ta5UzeJNvv14OGRlEw7hN6p4oyYq4+iK1RP9z0yHknIHbpR8 OkEy+DTwPx5qynCpl5dKhcYB2Fmevo+fvrUd+TbLjKqKp604kmWs/6/x6PsZoaleJfEO wYYU8SxvedjbN3Ic46dS3W/zjJB+j2f99xmOx4YkZODqKlR7duL35u2JYgSFby2H4Wbh 9RiEHNnOtxAm4JOs/whG3pGHZCUruXjTvr6P2zDUv0T1oTdSJZyVthiOXOKQgNyoZawh RgCw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:dkim-signature; bh=qHBgmM5FyY8tFESb+UZtZ7YHBNCfgMkVXvmSjVkn95c=; b=VyeVHWr9AZHTpTX4sczG8PbPa2nw6jVDD3scw0hTNigt79nq1q9spmH+pCTt2cbbBQ UJkmcR5N6cEbO0a2Q6QFCFFEGpckqPNCBOQJDxi2VMPLEMI+A5tNo9f9/51WfmT3HFse Ee8uxVP5fBTnJXfHwlfd4MGtfxIjAx/Q5bR3kcef/b0brkJoIf+iqBqqqn3Jc7paTyJZ kW6HqIT0jDyQtgfEEVpS0FVWHOtTTNxQNTIrsXIRRpK+ptfHMMKSKw20eNhFAZcaTYeE RYKnbENBEMzJHVEv6Eo81u49NMT89pzauUs9UIFqi5B1pxn5UoqSJrfdZ4Br04XbWVEd aThw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@google.com header.s=20210112 header.b=YIdgdTDl; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: from out1.vger.email (out1.vger.email. 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An app using madvise(,,MADV_COLLAPSE) should not be allowed to override it: restore its precedence over shmem_huge_force. Restore SHMEM_HUGE_DENY precedence over MADV_COLLAPSE. Fixes: 7c6c6cc4d3a2 ("mm/shmem: add flag to enforce shmem THP in hugepage_vma_check()") Suggested-by: Hugh Dickins Signed-off-by: Zach O'Keefe Cc: Yang Shi Cc: stable@vger.kernel.org --- v2->v3: Add 'Cc: stable@vger.kernel.org' as per stable-kernel-rules. v1->v2: Update changelog, and add note explaining rationale for backporting (Andrew Morton). Request to backport this to 6.1.X stable. We'd like SHMEM_HUGE_DENY to take precedence over MADV_COLLAPSE. If we make this change later, it will be a userspace API change. As such, 6.1 cannot be allowed to continue as-is, and we should fix up the code there. --- mm/shmem.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/shmem.c b/mm/shmem.c index c301487be5fb..0005ab2c29af 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -478,12 +478,10 @@ bool shmem_is_huge(struct vm_area_struct *vma, struct inode *inode, if (vma && ((vma->vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))) return false; - if (shmem_huge_force) - return true; - if (shmem_huge == SHMEM_HUGE_FORCE) - return true; if (shmem_huge == SHMEM_HUGE_DENY) return false; + if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE) + return true; switch (SHMEM_SB(inode->i_sb)->huge) { case SHMEM_HUGE_ALWAYS: