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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41F78C433F5 for ; Wed, 24 Nov 2021 22:19:06 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A330C6B0075; Wed, 24 Nov 2021 17:18:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 9E1DD6B0078; Wed, 24 Nov 2021 17:18:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8AACD6B007B; Wed, 24 Nov 2021 17:18:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0070.hostedemail.com [216.40.44.70]) by kanga.kvack.org (Postfix) with ESMTP id 7B94D6B0075 for ; Wed, 24 Nov 2021 17:18:50 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 4687F181CB142 for ; Wed, 24 Nov 2021 22:18:40 +0000 (UTC) X-FDA: 78845239242.10.3DCA941 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) by imf26.hostedemail.com (Postfix) with ESMTP id DF5F9200170A for ; Wed, 24 Nov 2021 22:18:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=sEQB/jjB9aOv3YFUMqLZKs+O/a2g4X/PQogVeTcsvsE=; b=polHpjfVG8fg9i75kJGRg4xa8D CijPbahqUUi6seetXzDtp8n06kzPDiMnhB3GaUMGLd7kErl1PoTA+lccFZQ2hzTVbKAIlyZfkImN6 95N4BlDXd2eMO/ra2dHy64j0Xn4RfSE67RfjHaROS7NfWxRxVYq4weKVDq2Hg4iV3HI1Ro8gXeGm8 WmlWYt/lK0jexevqrdMUfaqQ62P83MhmMR+FtpTbA0ZIOW5okWYttXWLm3kdMAYw8Hx+3a51yfie6 EAAicmCO0dfe7x2X34V/ETeS0yPHwR16+fg5U81qaC1Lj6vl4c4zoz4JBLfqe+6A+uG+F8coIQ4J+ UC1vzoGw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mq0b3-000KIU-PD; Wed, 24 Nov 2021 22:18:34 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 2B7C4986843; Wed, 24 Nov 2021 23:18:33 +0100 (CET) Date: Wed, 24 Nov 2021 23:18:33 +0100 From: Peter Zijlstra To: Peter Oskolkov Cc: Ingo Molnar , Thomas Gleixner , Andrew Morton , Dave Hansen , Andy Lutomirski , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, Paul Turner , Ben Segall , Peter Oskolkov , Andrei Vagin , Jann Horn , Thierry Delisle Subject: Re: [PATCH v0.9.1 3/6] sched/umcg: implement UMCG syscalls Message-ID: <20211124221833.GJ721624@worktop.programming.kicks-ass.net> References: <20211122211327.5931-1-posk@google.com> <20211122211327.5931-4-posk@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211122211327.5931-4-posk@google.com> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: DF5F9200170A X-Stat-Signature: w96cg4ic6x8q8hsshsrhnti14zpyp7pd Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=infradead.org header.s=desiato.20200630 header.b=polHpjfV; dmarc=none; spf=none (imf26.hostedemail.com: domain of peterz@infradead.org has no SPF policy when checking 90.155.92.199) smtp.mailfrom=peterz@infradead.org X-HE-Tag: 1637792318-645507 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Nov 22, 2021 at 01:13:24PM -0800, Peter Oskolkov wrote: > +die: > + pr_warn("%s: killing task %d\n", __func__, current->pid); > + force_sig(SIGKILL); That pr_warn() might need to be pr_warn_ratelimited() in order to no be a system log DoS. Because, AFAICT, you can craft userspace to trigger this arbitrarily often, just spawn a worker and make it misbehave.