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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 020B8C433EF for ; Sat, 2 Oct 2021 16:59:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C49FA61B28 for ; Sat, 2 Oct 2021 16:59:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233699AbhJBRBM (ORCPT ); Sat, 2 Oct 2021 13:01:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41326 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233659AbhJBRBL (ORCPT ); Sat, 2 Oct 2021 13:01:11 -0400 Received: from mail-ed1-x52f.google.com (mail-ed1-x52f.google.com [IPv6:2a00:1450:4864:20::52f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E8498C0613EC for ; Sat, 2 Oct 2021 09:59:24 -0700 (PDT) Received: by mail-ed1-x52f.google.com with SMTP id p13so18593448edw.0 for ; Sat, 02 Oct 2021 09:59:24 -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=7qMFTJ7wxvDKx7RqRNbyM5iYJL53fzpBAX1Z0cXGDYo=; b=BnC7AWn2t7U8hcMvbZB6+f8WRPJ/wlLxLWqJMBBFQqlt2pJ7o9Cq+PY7G8zlvkboG0 +aMmZjmiZyWkpgq/2TNa5lv+hVLEInO3k7cx6j+7mNevTzx3z8dSx+JapPEMt+QE7qnM jYwoWfCyKbjfVLLEkVydAP4vUyV5gl74Dwa/U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7qMFTJ7wxvDKx7RqRNbyM5iYJL53fzpBAX1Z0cXGDYo=; b=TBJkL8QXcQNdmTSo8zr1gsZuffwos94PXXYqRKt1KcW7PkZPlnWMAlOCk84JZYgchf vjwvXnWQCBZuT7HYkWyQoeZ+4L1l+g/u/pfnhNHQjmq/rux2RfNZzyTUK+EAYR3i1GtJ aneRxm29hB6M3Dqo+DpamCjAhreQh3X1pZWCjuy6zlc6ChpnKDnh0k55xrjaXE368QuD BCCMHShxyUdS3JZFID+iJSuEa7/5hszsn/lYaijSrdD4g45wYAexTLajn94/By3WxP08 qfLNsgYOr/FcHe2E6ORfyorojFvaefMONJG/piWaHXTtxZDcbHDGLrOGxpXy9kel6G9J dG3A== X-Gm-Message-State: AOAM532l4vmazKpA63dvZircNk0SjK2Sz+EOpyAk27uogfX/ZUdwWRQg VYRol3mv1cKA70bHbCytVAWnvOBTdroz0UqvBCA= X-Google-Smtp-Source: ABdhPJw56ri9MNP16arJtQ2hXlTRSLuoYkG6NheJyA1Rfnq1aCoOApZ777hQt9tF3KPBuL+usXneNw== X-Received: by 2002:aa7:cd41:: with SMTP id v1mr5134868edw.393.1633193963321; Sat, 02 Oct 2021 09:59:23 -0700 (PDT) Received: from mail-ed1-f52.google.com (mail-ed1-f52.google.com. [209.85.208.52]) by smtp.gmail.com with ESMTPSA id j16sm4845144edw.23.2021.10.02.09.59.23 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 02 Oct 2021 09:59:23 -0700 (PDT) Received: by mail-ed1-f52.google.com with SMTP id b8so12237308edk.2 for ; Sat, 02 Oct 2021 09:59:23 -0700 (PDT) X-Received: by 2002:a2e:3309:: with SMTP id d9mr4559712ljc.249.1633193585297; Sat, 02 Oct 2021 09:53:05 -0700 (PDT) MIME-Version: 1.0 References: <20210929185823.499268-1-alex.popov@linux.com> <20210929194924.GA880162@paulmck-ThinkPad-P17-Gen-1> In-Reply-To: From: Linus Torvalds Date: Sat, 2 Oct 2021 09:52:49 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter To: Alexander Popov Cc: Petr Mladek , "Paul E. McKenney" , Jonathan Corbet , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Joerg Roedel , Maciej Rozycki , Muchun Song , Viresh Kumar , Robin Murphy , Randy Dunlap , Lu Baolu , Kees Cook , Luis Chamberlain , Wei Liu , John Ogness , Andy Shevchenko , Alexey Kardashevskiy , Christophe Leroy , Jann Horn , Greg Kroah-Hartman , Mark Rutland , Andy Lutomirski , Dave Hansen , Steven Rostedt , Will Deacon , David S Miller , Borislav Petkov , Kernel Hardening , linux-hardening@vger.kernel.org, "open list:DOCUMENTATION" , Linux Kernel Mailing List , notify@kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 2, 2021 at 4:41 AM Alexander Popov wrote: > > And what do you think about the proposed pkill_on_warn? Honestly, I don't see the point. If you can reliably trigger the WARN_ON some way, you can probably cause more problems by fooling some other process to trigger it. And if it's unintentional, then what does the signal help? So rather than a "rationale" that makes little sense, I'd like to hear of an actual _use_ case. That's different. That's somebody actually _using_ that pkill to good effect for some particular load. That said, I don't much care in the end. But it sounds like a pointless option to just introduce yet another behavior to something that should never happen anyway, and where the actual honest-to-goodness reason for WARN_ON() existing is already being fulfilled (ie syzbot has been very effective at flushing things like that out). Linus 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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2793DC433F5 for ; Sat, 2 Oct 2021 16:53:39 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 4CEC561B00 for ; Sat, 2 Oct 2021 16:53:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 4CEC561B00 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.openwall.com Received: (qmail 30642 invoked by uid 550); 2 Oct 2021 16:53:31 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Received: (qmail 30610 invoked from network); 2 Oct 2021 16:53:30 -0000 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=7qMFTJ7wxvDKx7RqRNbyM5iYJL53fzpBAX1Z0cXGDYo=; b=BnC7AWn2t7U8hcMvbZB6+f8WRPJ/wlLxLWqJMBBFQqlt2pJ7o9Cq+PY7G8zlvkboG0 +aMmZjmiZyWkpgq/2TNa5lv+hVLEInO3k7cx6j+7mNevTzx3z8dSx+JapPEMt+QE7qnM jYwoWfCyKbjfVLLEkVydAP4vUyV5gl74Dwa/U= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=7qMFTJ7wxvDKx7RqRNbyM5iYJL53fzpBAX1Z0cXGDYo=; b=MU1BiUvgwXxf5EjLTg1CDCaD1lmXhKLuREsQzTCVMjqow+DbXUDb4aK+e+4epRSUW8 AQhjQuaEJ6U2PpPyroWFCz/sYFK+RrtA9XBLASTemjCFVAjUqvy7nmEh+fD4hqaJvf9c yZiGn8QxzYTMX3zXVnFL/iNux2NnufIAfct+uu8g6HViv6vFFewQZmtpGZjMwNx7zXHR qt391Z5UdG5raqnReoIVGTj0YPcl8kOYM93xPBRiMRjKwsXUaU29YMF/anEXzRQgJ4jD WhruQs1/muyM9iJOchCfpR9gGTCzhqACvIopkNuxM6Cu2JOsqx1Y2KWqZrnlRf4HV19B Fetg== X-Gm-Message-State: AOAM53222q06i6XGbqIOlbfa50+bLNei2hPAq0NmmZx4pMFtnIxOhTfp M9KcIfuwhSl1SEW/fFdXgNsosq63VAUiwNxxNek= X-Google-Smtp-Source: ABdhPJyeR3CInqFOIPGsMAKOl0mBASvSNdHeWLvbcDdj/65rU+phcPBNdAiQd9GXc08ag9711hfEKw== X-Received: by 2002:a2e:b545:: with SMTP id a5mr4626865ljn.48.1633193599053; Sat, 02 Oct 2021 09:53:19 -0700 (PDT) X-Received: by 2002:a2e:3309:: with SMTP id d9mr4559712ljc.249.1633193585297; Sat, 02 Oct 2021 09:53:05 -0700 (PDT) MIME-Version: 1.0 References: <20210929185823.499268-1-alex.popov@linux.com> <20210929194924.GA880162@paulmck-ThinkPad-P17-Gen-1> In-Reply-To: From: Linus Torvalds Date: Sat, 2 Oct 2021 09:52:49 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter To: Alexander Popov Cc: Petr Mladek , "Paul E. McKenney" , Jonathan Corbet , Andrew Morton , Thomas Gleixner , Peter Zijlstra , Joerg Roedel , Maciej Rozycki , Muchun Song , Viresh Kumar , Robin Murphy , Randy Dunlap , Lu Baolu , Kees Cook , Luis Chamberlain , Wei Liu , John Ogness , Andy Shevchenko , Alexey Kardashevskiy , Christophe Leroy , Jann Horn , Greg Kroah-Hartman , Mark Rutland , Andy Lutomirski , Dave Hansen , Steven Rostedt , Will Deacon , David S Miller , Borislav Petkov , Kernel Hardening , linux-hardening@vger.kernel.org, "open list:DOCUMENTATION" , Linux Kernel Mailing List , notify@kernel.org Content-Type: text/plain; charset="UTF-8" On Sat, Oct 2, 2021 at 4:41 AM Alexander Popov wrote: > > And what do you think about the proposed pkill_on_warn? Honestly, I don't see the point. If you can reliably trigger the WARN_ON some way, you can probably cause more problems by fooling some other process to trigger it. And if it's unintentional, then what does the signal help? So rather than a "rationale" that makes little sense, I'd like to hear of an actual _use_ case. That's different. That's somebody actually _using_ that pkill to good effect for some particular load. That said, I don't much care in the end. But it sounds like a pointless option to just introduce yet another behavior to something that should never happen anyway, and where the actual honest-to-goodness reason for WARN_ON() existing is already being fulfilled (ie syzbot has been very effective at flushing things like that out). Linus