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 85C96C4332F for ; Wed, 8 Nov 2023 19:41:50 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F326E8D00C5; Wed, 8 Nov 2023 14:41:49 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE1608D0073; Wed, 8 Nov 2023 14:41:49 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DA88A8D00C5; Wed, 8 Nov 2023 14:41:49 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id CEFAC8D0073 for ; Wed, 8 Nov 2023 14:41:49 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 9673A40C62 for ; Wed, 8 Nov 2023 19:41:49 +0000 (UTC) X-FDA: 81435807138.02.3F09995 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by imf07.hostedemail.com (Postfix) with ESMTP id DA1FF40004 for ; Wed, 8 Nov 2023 19:41:47 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=none; spf=pass (imf07.hostedemail.com: domain of "SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org" designates 145.40.68.75 as permitted sender) smtp.mailfrom="SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org"; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1699472508; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=6Xwni7wwXZl2g62Bbc2h7yIGOHJldwHoBHHalLDtgzw=; b=m5rm1RBhnUfloFikm1s5BM+DRvgfzQRRvH43Y7x7EoC4k716u0mnrfEjE5/jC5Goqlrqdv u7l2Mmbj4+5rfN1vDerbtdAMZpP7XdJDDBpbCfUZkPApKzfNpdQq1hNbXmmLs4tMOo2Qiz SffZQXdUGpP07r4LS0wtUlVlsLTgczw= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1699472508; a=rsa-sha256; cv=none; b=0yIJWUskCDKYYuomMXT7KDKAoUyhp4j7PV1y3bxAdMgwdlYlslrlj78xw4RdzKdLZhF6vP D0pX2P5jB3Um/sHcnzBv3q2opdFEG2HSou2gWRWJmh8JAHwZ9DjRCbYtw6X3B2eISWoJ8W qGLDQzsZyZvBMtMUoWx/RUkZBGXRQMo= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=none; spf=pass (imf07.hostedemail.com: domain of "SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org" designates 145.40.68.75 as permitted sender) smtp.mailfrom="SRS0=kuE6=GV=goodmis.org=rostedt@kernel.org"; dmarc=none Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by ams.source.kernel.org (Postfix) with ESMTP id 93675B81E6A; Wed, 8 Nov 2023 19:41:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AF815C433C7; Wed, 8 Nov 2023 19:41:40 +0000 (UTC) Date: Wed, 8 Nov 2023 14:41:44 -0500 From: Steven Rostedt To: Kees Cook Cc: Ankur Arora , linux-kernel@vger.kernel.org, tglx@linutronix.de, peterz@infradead.org, torvalds@linux-foundation.org, paulmck@kernel.org, linux-mm@kvack.org, x86@kernel.org, akpm@linux-foundation.org, luto@kernel.org, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, willy@infradead.org, mgorman@suse.de, jon.grimm@amd.com, bharata@amd.com, raghavendra.kt@amd.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, jgross@suse.com, andrew.cooper3@citrix.com, mingo@kernel.org, bristot@kernel.org, mathieu.desnoyers@efficios.com, geert@linux-m68k.org, glaubitz@physik.fu-berlin.de, anton.ivanov@cambridgegreys.com, mattst88@gmail.com, krypton@ulrich-teichert.org, David.Laight@aculab.com, richard@nod.at, mjguzik@gmail.com, Herbert Xu , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Thomas Graf Subject: Re: [RFC PATCH 71/86] treewide: lib: remove cond_resched() Message-ID: <20231108144144.3d257286@gandalf.local.home> In-Reply-To: <202311081114.0F15C1FB9@keescook> References: <20231107215742.363031-1-ankur.a.arora@oracle.com> <20231107230822.371443-1-ankur.a.arora@oracle.com> <20231107230822.371443-15-ankur.a.arora@oracle.com> <202311081114.0F15C1FB9@keescook> X-Mailer: Claws Mail 3.19.1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: wqcc6kcyeqgjo35wxx4uankenffbrrck X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: DA1FF40004 X-Rspam-User: X-HE-Tag: 1699472507-386493 X-HE-Meta: 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 mtnePC/1 vP5Kl5m9gX010E6/kMwxxhAiH0y0FlpvQJ7kuJ5crtAObrBBwnk2AXD1zIGtXsGzOJUbU+e2Ivsj0/nUiWZ0miz4zblIceNT4mQzmT/L5cYADsjG9f9b2ApRwh7bZrqUMnu8Jkrtu+a7+UvjX3NID+IA0S4Kj0K+0W1FOAA5daM6b6A+bCbe/2HuMfUt3M9R/ZnTmUujsoKMzOx3gPQ8XIa8oj7b3Sbj3h6PZMq30wVvToXtD7nzbOGsZ/rxq7MFweRNcWunJ2xVh8lb6qcaKgJ9mJKyGE7klCkIG4krtLIT3YUFUKnQ3vUtPqy/SAfFCALC+kqKflVsOPCQRhyMlF/B74f0jX//2/JEe 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: List-Subscribe: List-Unsubscribe: On Wed, 8 Nov 2023 11:15:37 -0800 Kees Cook wrote: > FOr the memcpy_kunit.c cases, I don't think there are preemption > locations in its loops. Perhaps I'm misunderstanding something? Why will > the memcpy test no longer produce softlockup splats? This patchset will switch over to a NEED_RESCHED_LAZY routine, so that VOLUNTARY and NONE preemption models will be forced to preempt if its in the kernel for too long. Time slice is over: set NEED_RESCHED_LAZY For VOLUNTARY and NONE, NEED_RESCHED_LAZY will not preempt the kernel (but will preempt user space). If in the kernel for over 1 tick (1ms for 1000Hz, 4ms for 250Hz, etc), if NEED_RESCHED_LAZY is still set after one tick, then set NEED_RESCHED. NEED_RESCHED will now schedule in the kernel once it is able to regardless of preemption model. (PREEMPT_NONE will now use preempt_disable()). This allows us to get rid of all cond_resched()s throughout the kernel as this will be the new mechanism to keep from running inside the kernel for too long. The watchdog is always longer than one tick. -- Steve