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=-3.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 85770C2D0A8 for ; Tue, 29 Sep 2020 02:05:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 34E57221E7 for ; Tue, 29 Sep 2020 02:05:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="EpFofk08" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727329AbgI2CFX (ORCPT ); Mon, 28 Sep 2020 22:05:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34658 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726961AbgI2CFX (ORCPT ); Mon, 28 Sep 2020 22:05:23 -0400 Received: from mail-pj1-x1031.google.com (mail-pj1-x1031.google.com [IPv6:2607:f8b0:4864:20::1031]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 75534C061755; Mon, 28 Sep 2020 19:05:23 -0700 (PDT) Received: by mail-pj1-x1031.google.com with SMTP id jw11so1819390pjb.0; Mon, 28 Sep 2020 19:05:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=iG/bDnzqe0Ijt5t+Wte/8y83V66TpQLjZGlUCfab1wM=; b=EpFofk08+f9XITxoematI1OddFtlpiCUaEhRU1X8Rf3an9Wf7Z359hgUmUFpbHoPlP 8RxfGcHxl0ll7p8Vv9aC0nB8jAe7BcKRPgFm1MJIUV9iNEvpimIJEC0XLsnt1/o09PcF +GLVK5dBh3fVli5MWTsCkWGgNgmhoTdolAxDXRIiqkfMi4eimOGaYCGATR+SVIHdsRRe 9mlew9d5gcr78P46fZ8EGcWjjz6bnPhryLd+yC3/II6dTOxBQ5NLB2GCCaAyLRCPKYv2 rPd5QHyrYZI4Q/h2/BO7k4yYlBisKMqi/mF5QSB++gKtFHSyPRDoj4d0X7CICgzyDec8 3y1w== 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:mime-version :content-disposition; bh=iG/bDnzqe0Ijt5t+Wte/8y83V66TpQLjZGlUCfab1wM=; b=GITYyTXUu+joFGvxRbVicd6Joh7V+S65i8Y7o5GMxQXRMgkTcgAJnp6sV/CMQT8aCc nz81fKNIjj/lb7LZyxbNBISV7i+EBfPbHDrIDOiyBG7cvEZxqG3unU8970sxcQbHorh9 llFOdSndaaBrAHv7n2y6KNwIPjkDDdkiZHpqp3bbnqGKQFQH1pkowTASlndsaJ3O6kvR 3tKYyTx6/mpDHmdcM49DoTolEN+u0MRSdbLMv/9bcv9CrxbjUlSwU4A9aLVWNpL5FnUz v9xBkXd90zoNkNTRyKBIe0meUhkSoU1NvXar4oW2KRaXxG55i9W0VeVlc+Uxd2JHbRK9 xTvg== X-Gm-Message-State: AOAM532U/T+5RrMs5foNiMAFUVI2buskkbGLMQUuvntLqucLnSxWjS+l NJZ4PF/6OdTcLTghSA0DOjE= X-Google-Smtp-Source: ABdhPJxJpmMaNJwZ6htIVmhNPWkcCWKRWoXVeHqM+7TyR3A1gD0li91bQ1A0WrWY5y6DMA7aPmnDtA== X-Received: by 2002:a17:90a:c255:: with SMTP id d21mr1857806pjx.212.1601345122954; Mon, 28 Sep 2020 19:05:22 -0700 (PDT) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id 31sm2577845pgs.59.2020.09.28.19.05.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 28 Sep 2020 19:05:21 -0700 (PDT) Date: Tue, 29 Sep 2020 11:05:20 +0900 From: Sergey Senozhatsky To: Alexey Dobriyan , Andrew Morton , Vlastimil Babka , Kees Cook , Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Sergey Senozhatsky Subject: [RFC] process /proc/PID/smaps vs /proc/PID/smaps_rollup Message-ID: <20200929020520.GC871730@jagdpanzerIV.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, One of our unprivileged daemon process needs process PSS info. That info is usually available in /proc/PID/smaps on per-vma basis, on in /proc/PID/smaps_rollup as a bunch of accumulated per-vma values. The latter one is much faster and simpler to get, but, unlike smaps, smaps_rollup requires PTRACE_MODE_READ, which we don't want to grant to our unprivileged daemon. So the question is - can we get, somehow, accumulated PSS info from a non-privileged process? (Iterating through all process' smaps vma-s consumes quite a bit of CPU time). This is related to another question - why do smaps and smaps_rollup have different permission requirements? -ss