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=-2.8 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 9495DC4332E for ; Tue, 19 Jan 2021 10:57:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4CCF92075F for ; Tue, 19 Jan 2021 10:57:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391085AbhASKws (ORCPT ); Tue, 19 Jan 2021 05:52:48 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59582 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732309AbhASKjK (ORCPT ); Tue, 19 Jan 2021 05:39:10 -0500 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CBFA0C0613C1 for ; Tue, 19 Jan 2021 02:38:28 -0800 (PST) Received: by mail-pf1-x42b.google.com with SMTP id 11so11973269pfu.4 for ; Tue, 19 Jan 2021 02:38:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=ejd8L+qRikTAX4gXzqidXEApmypCJiiNo1NE206AbrU=; b=TrGffkS01nDzRU7dB1hHdZmPTZLmx/da9Ynj+GGoboJow3+onFraH7/z5rJ8r4l7jv 31Wg5dZGXKp09MUvj83JMo942VlkIKRNqSFlUJ9D+g+8ZUu5apJdtB7uIfyRrWA2PAiD 2aC6u0Ql0J6m40Iw6Sn9broA6Q5kLHAs3QXJHMbFJdWxjAATIfBkavJx4uZ2TXGpXxKt xdp1btuYiN4UFX2NjSPO+LeeHde5uO1ug9RmdVIgKhdtI0glVz6Yb6+d4NPTUtBBqoO8 QMINwq0yHsLRoMdkzzrPn7M872w2ZgqIevFGJ8XBDAYzlZzKVwwkQiNWTnOtt280gTdm xo7A== 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=ejd8L+qRikTAX4gXzqidXEApmypCJiiNo1NE206AbrU=; b=Xg4FB1v2o/8GRAKPP3fA9D5yacVJ5kSlel2XDeXONTW2G0c87cm2Nzxz5mdg2W3YQE 0C9L3hQ0saHs2k9A5L5OaYRKsHSJ3TKvIeMXNmi/33E9W5oT8ucpc7zrTs5PHUt2Dd5+ g+cyB4euNya4DyfysS+CR1R3q2nmTuFl/TFJZjnhJPwzH+sjZnQXyb8WUWofgJR6ULkG RvK4xy8mwckyF9hGlBpxKtX7As2RdlYevXL4azfEaNz9OhVPRC/RYlOMToyJ6wuGuE8S 1X12rZDTMvzk+Wfp7DOKky9O0kKgTjFTXLejDoZuFUOutj9PcymrRZg8ppHuYIXBoYzw VW6g== X-Gm-Message-State: AOAM532wWqhjGfGRT3KbHpS+w2TT/ibNMd8tAp0zratbCNebMlbkvXlT OG9D1HZKA+y05f4UJVvysk5hsaqwKgeHng== X-Google-Smtp-Source: ABdhPJySP5Rw43ok+Y96nXNziyr2vBqLw0NM1092NvgvoyFuLMZ8pxmbMOjvCgu1t5gJvLHfg5pBRA== X-Received: by 2002:a63:3049:: with SMTP id w70mr3816048pgw.224.1611052708331; Tue, 19 Jan 2021 02:38:28 -0800 (PST) Received: from localhost ([2409:10:2e40:5100:6e29:95ff:fe2d:8f34]) by smtp.gmail.com with ESMTPSA id t8sm2753229pjm.45.2021.01.19.02.38.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Jan 2021 02:38:27 -0800 (PST) Date: Tue, 19 Jan 2021 19:38:24 +0900 From: Sergey Senozhatsky To: Matthew Wilcox Cc: Sergey Senozhatsky , Timur Tabi , Andrew Morton , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, Petr Mladek , roman.fietze@magna.com, keescook@chromium.org, Steven Rostedt , John Ogness , linux-mm@kvack.org, Akinobu Mita Subject: Re: [PATCH 0/2] introduce DUMP_PREFIX_UNHASHED for hex dumps Message-ID: References: <20210116220950.47078-1-timur@kernel.org> <20210118182635.GD2260413@casper.infradead.org> <20210119014725.GH2260413@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210119014725.GH2260413@casper.infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On (21/01/19 01:47), Matthew Wilcox wrote: [..] > > > So maybe DUMP_PREFIX_UNHASHED can do the unhashed dump only when > > CONFIG_DEBUG_KERNEL=y and fallback to DUMP_PREFIX_ADDRESS otherwise? > > Distros enable CONFIG_DEBUG_KERNEL. Oh, I see. > If you want to add CONFIG_DEBUG_LEAK_ADDRESSES, then that's great, > and you won't even have to change users, you can just change how %p > behaves. I like the name. config dependent behaviour of %p wouldn't be new, well, to some extent, e.g. XFS does something similar (see below). I don't think Linus will be sold on this, however. fs/xfs/xfs_linux.h: /* * Starting in Linux 4.15, the %p (raw pointer value) printk modifier * prints a hashed version of the pointer to avoid leaking kernel * pointers into dmesg. If we're trying to debug the kernel we want the * raw values, so override this behavior as best we can. */ #ifdef DEBUG # define PTR_FMT "%px" #else # define PTR_FMT "%p" #endif And then they just use it as xfs_alert(mp, "%s: bad inode magic number, dip = "ptr_fmt", dino bp = "ptr_fmt", ino = %ld", __func__, dip, bp, in_f->ilf_ino); -ss