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=-11.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 39E93C433C1 for ; Mon, 22 Mar 2021 21:02:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04CC5619A0 for ; Mon, 22 Mar 2021 21:02:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230185AbhCVVBc (ORCPT ); Mon, 22 Mar 2021 17:01:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:44969 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231426AbhCVVAm (ORCPT ); Mon, 22 Mar 2021 17:00:42 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1616446837; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=c6WtZIP3Pv8Sts2xBUJYEw6AY7dI8VFWAi8J8oYd58g=; b=cnNa14zJM7Iw0L9MacPUVRv78ekcTuGDFhh+VEJC4mgLPYkvReI6FEZiaGfWdGVhruXwFy rNU/mh4v3lBgJiaGsvYCl7PmLEqHHWmp5GK0pWdEzr0XzpnU0q+b7B9rZWrE68VH+IaOq7 GFlL5duQCfAUm4jof0bRNuyEGrmACzw= Received: from mail-qk1-f197.google.com (mail-qk1-f197.google.com [209.85.222.197]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-339-fSL959CeMN2NapDtAC5Kxw-1; Mon, 22 Mar 2021 17:00:35 -0400 X-MC-Unique: fSL959CeMN2NapDtAC5Kxw-1 Received: by mail-qk1-f197.google.com with SMTP id y22so408034qkb.23 for ; Mon, 22 Mar 2021 14:00:35 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=c6WtZIP3Pv8Sts2xBUJYEw6AY7dI8VFWAi8J8oYd58g=; b=rwiss8gksnDgiaQPI530uCk9mpUsEnviVIQeq46+r6FO0E28HG3WKXmGAIDbdVhCNX /oyhmWI1JQQbGz7q6e+xXlpWXB6chpnW3xRBNje0WY/0H0m/GV49BO/0mn/SK/uuhgOk nYjg4OUYyDYOMEsdm7wGMjCcmgUksqZuyEL+jyyu1xSB3mxtnhKORsAA1LlCfl18QcJV aEHTHy98EFVEndYCCzl7YLp6Epsq3uxSLCUX4adMLhmNMxpHVxi8voS2l6U5hCZTrswD CJ96zzgRR6mFkJsOk8UJI9riMSZUv1x7biBoS40qBx3j6om6ZsrpmYMxGcwvdWIB+uJv ZAHA== X-Gm-Message-State: AOAM533CHzswvtYtp3WrFarJVzSVvAVWgAfUhqkHodfLxO100dnMzQpn jWbDlGiRXkxs+vTSVt47n+4KPU7i0J2mtNNndiLhSxzYM+Xgg4S88ga8QZ1ODcQBTy+Mh+V1GWA 0p70aP1/DlJMZbHlzG4aRnBWUBWFc X-Received: by 2002:a37:b07:: with SMTP id 7mr1967520qkl.437.1616446834811; Mon, 22 Mar 2021 14:00:34 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwQd0PhyYegD6z3hStlomrWz7fldh8CLfj/9QsIxn62XAVmyQ2p22XQ5XNwdBsS8CuH5dU6Lg== X-Received: by 2002:a37:b07:: with SMTP id 7mr1967476qkl.437.1616446834557; Mon, 22 Mar 2021 14:00:34 -0700 (PDT) Received: from xz-x1 (bras-base-toroon474qw-grc-82-174-91-135-175.dsl.bell.ca. [174.91.135.175]) by smtp.gmail.com with ESMTPSA id b17sm9688484qtp.73.2021.03.22.14.00.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Mar 2021 14:00:34 -0700 (PDT) Date: Mon, 22 Mar 2021 17:00:31 -0400 From: Peter Xu To: Axel Rasmussen Cc: Alexander Viro , Andrea Arcangeli , Andrew Morton , Hugh Dickins , Jerome Glisse , Joe Perches , Lokesh Gidra , Mike Rapoport , Shaohua Li , Shuah Khan , Wang Qing , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Brian Geffon , Cannon Matthews , "Dr . David Alan Gilbert" , David Rientjes , Michel Lespinasse , Mina Almasry , Oliver Upton Subject: Re: [PATCH] userfaultfd/shmem: fix minor fault page leak Message-ID: <20210322210031.GH16645@xz-x1> References: <20210322204836.1650221-1-axelrasmussen@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20210322204836.1650221-1-axelrasmussen@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org On Mon, Mar 22, 2021 at 01:48:35PM -0700, Axel Rasmussen wrote: > This fix is analogous to Peter Xu's fix for hugetlb [0]. If we don't > put_page() after getting the page out of the page cache, we leak the > reference. > > The fix can be verified by checking /proc/meminfo and running the > userfaultfd selftest in shmem mode. Without the fix, we see MemFree / > MemAvailable steadily decreasing with each run of the test. With the > fix, memory is correctly freed after the test program exits. > > Fixes: 00da60b9d0a0 ("userfaultfd: support minor fault handling for shmem") > Signed-off-by: Axel Rasmussen Reviewed-by: Peter Xu -- Peter Xu