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=-5.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 F1264C433E0 for ; Thu, 25 Mar 2021 20:44:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B8F9161A14 for ; Thu, 25 Mar 2021 20:44:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230189AbhCYUnv (ORCPT ); Thu, 25 Mar 2021 16:43:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230346AbhCYUnV (ORCPT ); Thu, 25 Mar 2021 16:43:21 -0400 Received: from mail-il1-x12c.google.com (mail-il1-x12c.google.com [IPv6:2607:f8b0:4864:20::12c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 87A09C06175F for ; Thu, 25 Mar 2021 13:43:21 -0700 (PDT) Received: by mail-il1-x12c.google.com with SMTP id t14so3277000ilu.3 for ; Thu, 25 Mar 2021 13:43:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=TSU2B9M8vT24A3F3SJwsUrhSuRDhhujYOX5JFBLr5Q4=; b=cum/hZjQOua9qB39aJPqFwe/yq6t1irZ+vOZH+c75W/UaRUYiV/tu7M7foPTezWsJ7 HsviJkXLRtZHBPeo4nrdkQBBUtDxt55s0Xy+0OITg//vgiAQw6/vyPGfK4eRHJEmkDCZ 823G1X77A5BLgs8cVAjNtAle83ZBnoJows4t9y3n/jYmjlTj0i4M1CWi1TywtNJUT9bV 3Hw3/dd4FOrPhI7cMy3aELH/Ooa7wLm3LbBYexHHMuQwsOJ++B/Q0VRigu/Zzh7GgGYf RwjIZKn/wJw7LHGMX7TAXRL5kne2oOoed1VDLag51C0PvbQXe9hoGE8BnlB7f2GNqOOu krrA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=TSU2B9M8vT24A3F3SJwsUrhSuRDhhujYOX5JFBLr5Q4=; b=oZBlLVduajbd6menwz2Os5y0e/mqRwK3oDezUk7k9IHR55EC5kAAPho5Btp8D/0bhL qTXXUZzeRklMiBUW+6srhE3kc4bOSNSRudrVHrIC6Z8dXAiWbKLDgN3ASNlSCjGlhM+4 NmnQScwJrilQiioy0msNzG3LNDuia0mHBIx7JF/thUo3R7fAsro7vOBnCSWoTpTseBG5 I5eoUENAWKgNR8n7svIeDGsTapgJyt0s0i+0LaVgZvd+veAzV+Uvw67R15zX86ovk7Uj QT2kPurG9Jy+GyLpRT+kaGsMThd2vyqKWu/HXBDhNzju4AtImU2LDeZL2GaChqnmeu+4 qk9w== X-Gm-Message-State: AOAM532svc0YyJTcvNT7xTJEuhQlLyfh1CH9+2q++4F710ZdDOpAGVMr JZZwi2TxHw+aBiRoqoFpk2RrbQ== X-Google-Smtp-Source: ABdhPJy/uscIu0RMY2L8VvuCw+SSmMM4pcYhmikvk3jc8cxC6+l7v3f50aaGHwcTH0r4fduhMtW0Qw== X-Received: by 2002:a92:bd06:: with SMTP id c6mr8562506ile.158.1616705000985; Thu, 25 Mar 2021 13:43:20 -0700 (PDT) Received: from [192.168.1.30] ([65.144.74.34]) by smtp.gmail.com with ESMTPSA id o10sm3181138ilf.46.2021.03.25.13.43.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 25 Mar 2021 13:43:20 -0700 (PDT) Subject: Re: [PATCH 0/2] Don't show PF_IO_WORKER in /proc//task/ To: Oleg Nesterov , "Eric W. Biederman" Cc: Linus Torvalds , io-uring , Linux Kernel Mailing List , Stefan Metzmacher References: <20210325164343.807498-1-axboe@kernel.dk> <3a1c02a5-db6d-e3e1-6ff5-69dd7cd61258@kernel.dk> <20210325204014.GD28349@redhat.com> From: Jens Axboe Message-ID: <70232822-ced2-30e8-f880-8ebadacc9cc2@kernel.dk> Date: Thu, 25 Mar 2021 14:43:20 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20210325204014.GD28349@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 3/25/21 2:40 PM, Oleg Nesterov wrote: > On 03/25, Eric W. Biederman wrote: >> >> So looking quickly the flip side of the coin is gdb (and other >> debuggers) needs a way to know these threads are special, so it can know >> not to attach. > > may be, > >> I suspect getting -EPERM (or possibly a different error code) when >> attempting attach is the right was to know that a thread is not >> available to be debugged. > > may be. > > But I don't think we can blame gdb. The kernel changed the rules, and this > broke gdb. IOW, I don't agree this is gdb bug. Right, that's what I was getting at too - and it's likely not just gdb. We have to ensure that we don't break this use case, which seems to imply that we: 1) Just make it work, or 2) Make them hidden in such a way that gdb doesn't see them, but regular tooling does #2 seems fraught with peril, and maybe not even possible. -- Jens Axboe