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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 2BE39C2BA19 for ; Thu, 9 Apr 2020 21:18:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DA2E820753 for ; Thu, 9 Apr 2020 21:18:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586467083; bh=iFJ2uXSUtewQGy/XQWzDbwdljeWyAp5lFEbtIqeww1M=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=e7gDIQktE7fVBVgiBtWPEr5aTz+7sSJP8x7jTh8FROBi/EcDQeTvxHHEntV8orTyd uSfEKY8vOga7P5RkSPzayIXjuGnczK8Xh/h2HFrR9oKnwNH1uCP/x/sJ2nV4Badhzp sopt/u6i3KvZT31rWZx0yebEo9N6M8I2gPxvd9P0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727481AbgDIVSB (ORCPT ); Thu, 9 Apr 2020 17:18:01 -0400 Received: from mail-lf1-f65.google.com ([209.85.167.65]:34783 "EHLO mail-lf1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726964AbgDIVSB (ORCPT ); Thu, 9 Apr 2020 17:18:01 -0400 Received: by mail-lf1-f65.google.com with SMTP id x23so782137lfq.1 for ; Thu, 09 Apr 2020 14:17:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=y3ANlkc73xfE7W9i+/i/PzZhTTMot1WbopUumX0rZso=; b=TxHSnl5hL9hBLbhzpFFxIIOfEr8Xnaemb9ujkuS20q7mBQjEQ06csx2hlFV+zrgpup 6dO7d2KwP2bItlzFl438olGyiqFuJzQzU5T7C+QmihScFUaRPswsPZ54xGuUwj654Q74 W0Ot8qmNDtMNw7H16o5lyW+WTWJ6YCHGAvMqQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=y3ANlkc73xfE7W9i+/i/PzZhTTMot1WbopUumX0rZso=; b=jalHcjSK3avGFcds5HbbX9rL8eIQnEpFv28LSkKBqxcMDGvEpp0UzEPY1GT8doEPBY v/KKGdQ0vQruHfeGmDEJWNnZVpt7609XPepfu5FP8Y9dQWYzCyN/KyQrAwwo2emkJIT+ pxEUgRf5C0IB0zHqN+1Rsy/oJ9qomr1byyg0HXOpNRpsh0mDRmI8/jAhUPacCYwfDgtw U3IMKbszmMosJYlDcZ/Cxv+RF40xy+KFF5GWfcKt7QT/e6fVA9vMuuUaTT5lznE9OUgv YD3ztBKWqrMo7cJHOC9XU/hVVmHuFPnce8m6hBmSrn2HqjNs2RUgN+tONPuXoNQlYMgK UJPQ== X-Gm-Message-State: AGi0Puac6Z60FlvR/6TcTlb+XaODb+/2w7pO2TrF9Zn+u10tH3PKcEPt eOOGLt+qdiGzwMNSJmq//3ldmShcnw4= X-Google-Smtp-Source: APiQypKxDJMFR7PjDUPYyEodmyzYF91/4JicIAbIzgWah1jse6jfu12DJ2le7+cFqnEKFh69a9qM+Q== X-Received: by 2002:a19:e00e:: with SMTP id x14mr714332lfg.111.1586467076718; Thu, 09 Apr 2020 14:17:56 -0700 (PDT) Received: from mail-lf1-f51.google.com (mail-lf1-f51.google.com. [209.85.167.51]) by smtp.gmail.com with ESMTPSA id y29sm16102785ljd.26.2020.04.09.14.17.55 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Apr 2020 14:17:55 -0700 (PDT) Received: by mail-lf1-f51.google.com with SMTP id 131so740769lfh.11 for ; Thu, 09 Apr 2020 14:17:55 -0700 (PDT) X-Received: by 2002:ac2:4466:: with SMTP id y6mr699561lfl.125.1586467075152; Thu, 09 Apr 2020 14:17:55 -0700 (PDT) MIME-Version: 1.0 References: <87blobnq02.fsf@x220.int.ebiederm.org> <87lfnda3w3.fsf@x220.int.ebiederm.org> <87blo45keg.fsf@x220.int.ebiederm.org> <87v9maxb5q.fsf@x220.int.ebiederm.org> <87y2r4so3i.fsf@x220.int.ebiederm.org> <87wo6or3pg.fsf@x220.int.ebiederm.org> <87imi8nzlw.fsf@x220.int.ebiederm.org> In-Reply-To: <87imi8nzlw.fsf@x220.int.ebiederm.org> From: Linus Torvalds Date: Thu, 9 Apr 2020 14:17:39 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] Please pull proc and exec work for 5.7-rc1 To: "Eric W. Biederman" Cc: Bernd Edlinger , Waiman Long , Ingo Molnar , Will Deacon , Linux Kernel Mailing List , Alexey Gladkov , Oleg Nesterov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 9, 2020 at 2:03 PM Eric W. Biederman wrote: > > But no. While you are goind a good job at spotting odd corner > cases that need to be fixed. This also is not the cause of the > deadlock. It is nothing that subtle. So Eric, I'm now going to stop wasting my time on arguing with you. Since both you and Bernd claimed to be too busy to even bother testing that thing, I just built it and booted it. And guess what? That thing makes your non-deadlock thing go away. So it's _literally_ that simple. Now, does it make the tests "pass"? No. Because the "vmaccess" test fails because the open() now fails - because we simply don't wait for that dead thread any more, so the /proc//mem thing doesn't exist. And for the same reason that "attach" test now no longer returns EAGAIN, it just attaches to the remaining execlp thing instead. So I'm not just good at "spotting odd corner cases". I told you why that bogus deadlock of yours failed - the execve was pointlessly waiting for a dead thread that had marked itself ptraced, and nobody was reaping it. And it appears you were too lazy to even try it out. Yes, that whole "notify_dead" count vs "tsk->exit_state" test is fundamentally racy. But that race happens to be irrelevant for the test case in question. So until you can actually add something to the discussion, I'm done with this thread. Linus