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=-0.8 required=3.0 tests=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 622D8C433DF for ; Fri, 19 Jun 2020 07:58:53 +0000 (UTC) Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1DC86207DD for ; Fri, 19 Jun 2020 07:58:52 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1DC86207DD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=vt.edu Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernelnewbies-bounces@kernelnewbies.org Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.94) (envelope-from ) id 1jmBuo-0001jO-3Z; Fri, 19 Jun 2020 03:58:22 -0400 Received: from omr1.cc.ipv6.vt.edu ([2607:b400:92:8300:0:c6:2117:b0e] helo=omr1.cc.vt.edu) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1jmBul-0001jE-OF for Kernelnewbies@kernelnewbies.org; Fri, 19 Jun 2020 03:58:19 -0400 Received: from mr1.cc.vt.edu (smtp.ipv6.vt.edu [IPv6:2607:b400:92:9:0:9d:8fcb:4116]) by omr1.cc.vt.edu (8.14.4/8.14.4) with ESMTP id 05J7wIFB017905 for ; Fri, 19 Jun 2020 03:58:18 -0400 Received: from mail-qv1-f70.google.com (mail-qv1-f70.google.com [209.85.219.70]) by mr1.cc.vt.edu (8.14.7/8.14.7) with ESMTP id 05J7wDct000827 for ; Fri, 19 Jun 2020 03:58:18 -0400 Received: by mail-qv1-f70.google.com with SMTP id s15so6054968qvo.6 for ; Fri, 19 Jun 2020 00:58:18 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:in-reply-to:references :mime-version:content-transfer-encoding:date:message-id; bh=xB+W0h9n05ceCduFeZhuLf5UE2DACYRlgOh6HhZoD/Q=; b=Jhrn1tNVfmUs7dR6+1hAd2xC7JKeulrSxgWmtUjFG7gI2xlwTZ0ylM6iIGMrJgeuZa Vrr83DeQXdDt+9lMC62hpA7GhaWQL1XYjLBHxkHoDI9/+0GdcihccKh94qU9usCcZmvl nS7bTposebFWxBnDhy0aSqzIsQeRyUyTFY/jO5H8N5j5gg/kqmEXoBiESc2Eo5H/DRq3 SIP6MBHdXBcBjsxgIwVGMjbOBTOSDZXeSErb3B+lgw4b2T5zTRvYohAhw9wLEiXWqzEr ZPEfpzM4fjrvY+2NOxpwU/k5Jb85tFG32qWj9O0cNju83jwhsPYy3gKFRZhIigIglaYv 0oLA== X-Gm-Message-State: AOAM532NFj+eEUYIiOn1bIhtjuDW5bTqvEFlU6bgBZOi68hpu/FaTzQ4 2KEjZnXKGKlBtQBCiSsZLjZOjHuL31EM0A9E9w6/rUy8sVENm/t7yne0GOv94S6T9xn4STftkPf +fIF2xNqNbcCbsKCzx03z6fpa75j7aDdcJWZn4uc= X-Received: by 2002:a05:6214:144:: with SMTP id x4mr7272182qvs.229.1592553493114; Fri, 19 Jun 2020 00:58:13 -0700 (PDT) X-Google-Smtp-Source: ABdhPJx99bf41anDntMCSO0tmC5OwSDWcUcF8bsMefyiL5J9PPkHK+C+9n3d1Uh4LiwvPia6uTUGcQ== X-Received: by 2002:a05:6214:144:: with SMTP id x4mr7272141qvs.229.1592553491847; Fri, 19 Jun 2020 00:58:11 -0700 (PDT) Received: from turing-police ([2601:5c0:c001:c9e1::359]) by smtp.gmail.com with UTF8SMTPSA id t43sm6251098qtj.85.2020.06.19.00.58.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 19 Jun 2020 00:58:10 -0700 (PDT) From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Google-Original-From: "Valdis Kl=?utf-8?Q?=c4=93?=tnieks" X-Mailer: exmh version 2.9.0 11/07/2018 with nmh-1.7+dev To: 孙世龙 Subject: Re: There is a question mark in front of the function name in the call trace log.What does the question mark imply? In-Reply-To: References: Mime-Version: 1.0 Date: Fri, 19 Jun 2020 03:58:09 -0400 Message-ID: <468303.1592553489@turing-police> Cc: Kernelnewbies@kernelnewbies.org X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============3995659391843493787==" Errors-To: kernelnewbies-bounces@kernelnewbies.org --===============3995659391843493787== Content-Type: multipart/signed; boundary="==_Exmh_1592553489_62491P"; micalg=pgp-sha1; protocol="application/pgp-signature" Content-Transfer-Encoding: 7bit --==_Exmh_1592553489_62491P Content-Type: text/plain; charset=us-ascii On Fri, 19 Jun 2020 13:29:09 +0800, 孙世龙 said: > I have never seen such a call trace log before: there is a question > mark(i.e. symbol of "?") in front of the function name. What does the > question mark imply? > > Here is the related log: > > [22041.387697] Call Trace > [22041.387711] dump_stack+0x9e/0xc8 > [22041.387718] warn_alloc+0x100/0x190 > [22041.387725] __alloc_pages_slowpath+0xb93/0xbd0 > [22041.387732] __alloc_pages_nodemask+0x26d/0x2b0 > [22041.387739] alloc_pages_current+0x6a/0xe0 > [22041.387744] kmalloc_order+0x18/0x40 > [22041.387748] kmalloc_order_trace+0x24/0xb0 > [22041.387754] __kmalloc+0x20e/0x230 > [22041.387759] ? __vmalloc_node_range+0x171/0x250 > [22041.387765] xnheap_init+0x87/0x200 > [22041.387770] ? remove_process+0xc0/0xc0 > [22041.387775] cobalt_umm_init+0x61/0xb0 There's various ways the stack unwinder for the call trace can work. On some architectures, there is an explicit stack pointer register, and it's saved in the stack by the 'call' opcode, so unwinding can be exact. On other systems, an explicit stack pointer is optional (such as on x86, where not building with one allows one more temporary register, which can help with efficient code generation). There, unwinds are inexact - it basically steps through the stack and finds entries that are viable pointers into the kernel/module executable code space. Sometimes, it will find what looks like a return pointer but it's not at a plausible location in the stack entry, so it may be trash left on the stack, so it flags it with a '?' --==_Exmh_1592553489_62491P Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Comment: Exmh version 2.9.0 11/07/2018 iQIVAwUBXuxwEAdmEQWDXROgAQJ4jBAAoziHBV1CcUpYkgngG8EPi9Z4ENvMcvyv GpNwEiueQFzQVgPqsme/whzU5TrEUsvJ9caSx9RrdaYNXj/aJySsnG3g/XRA+rSr IuwosICPqX0ATobPwu3EqCgCBWhwP1k26+p8g4Vum9joQxadGJFROsfqwKUFlVOn HHMZqxCrmThRqFg0lGVcFAw15AoV48nwqgi2/Lj58z0WSpqjehKJhEpYA7n69gY2 uvr6UsVBrPwfJRrBLquOWQCSObKksy/mCb+pRiQUbQ6p4haK/I8RDksjwyqusDCP /TToW2FRw2zmu3i4btIWCJo8WhSVkm4iYXIi6+X9a+ibL21Pv8kDUN+ahKVP9QPy upyYAH8CgJyFKtZooTUN8W7rs6wIUYphNtpZScVsL5AQSmukqa1CdeAofZByvBSB H0f/2tQJlc7xwWHmGXux9yPFyk5Xe3VLlPnq1vg3FLFCrfCDvbdU0A78lKE9knf8 Aheu0c5UXBAaI3KR7FDmRLv6bCpVYiPy5bv7o6KDzieUcXsASPjg520k67GQ237y vfFAuftGVwYjfTgAseDFrHqP5FxfirSQAY5GrsyVMQ6rNgWxIcXy64mGByZuQYZw UySI89CNmvtUz9R0LE/2mxN1odeulEuuShd3qkmndc4hFZZIEDpTElDnZ0YC3MOf nzQRrJdVy4Q= =MrGg -----END PGP SIGNATURE----- --==_Exmh_1592553489_62491P-- --===============3995659391843493787== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies --===============3995659391843493787==--