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]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 35D6CC5B572 for ; Tue, 11 Aug 2026 14:42:28 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2BF866B008A; Tue, 11 Aug 2026 10:42:27 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 222726B008C; Tue, 11 Aug 2026 10:42:27 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 09F726B0095; Tue, 11 Aug 2026 10:42:27 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id DD5816B008A for ; Tue, 11 Aug 2026 10:42:26 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 6B03A1C1288 for ; Tue, 11 Aug 2026 14:42:26 +0000 (UTC) X-FDA: 85089254292.30.8021E29 Received: from relay.hostedemail.com (unirelay03 [10.200.18.66]) by imf05.hostedemail.com (Postfix) with ESMTP id AEFF7100009 for ; Tue, 11 Aug 2026 14:42:24 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1786459344; 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=gcSfS7QNtE6S94cqoaez+NvxQo3hToTMKglv3I/la3A=; b=u3jh4i/NUY76sNKtkjKYi9s6QyYNWcumOuNdME+PL4jN64WyG/4RQMiIJS6R68lkI09fgT y5ogSuedbKy4YiOUMX+IaON+MQWSn0roxn52Bq8ob/Zu7QSGu6WJEdImZ7gqrNWFBn+m/C lW20NnQz7QPdvDhc5dqAlBHRwXPhQ94= ARC-Authentication-Results: i=1; imf05.hostedemail.com; none ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1786459344; b=yyeupxgzShOzBGv/h5LnZSrYS0BdQj8X/vFDqStuLu2IWHe1elLz+Gbx4AK6xbM2KUBEFU j0pjEcn7tqJsSVMmQHOscatbRboBQ/sd3jUp7tXBkzAlGSMUmQdR6Rydk35akzgCyMCeG5 TJhNnTuWWGS/USHbX4x6G5Aef4eh36s= Received: from omf06.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 80210A04AB; Tue, 11 Aug 2026 14:42:22 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf06.hostedemail.com (Postfix) with ESMTPA id 1BDE720010; Tue, 11 Aug 2026 14:42:18 +0000 (UTC) Date: Tue, 11 Aug 2026 10:42:29 -0400 From: Steven Rostedt To: David Woodhouse Cc: Jason Gunthorpe , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Sebastian Andrzej Siewior , Clark Williams , Simona Vetter , =?UTF-8?B?SsOpcsO0bWU=?= Glisse , Christian =?UTF-8?B?S8O2bmln?= , "Paul E. McKenney" , Sean Christopherson , Paolo Bonzini , linux-mm@kvack.org, kvm@vger.kernel.org, linux-rt-devel@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mmu_notifier: Remove non_block_start/end() from notifier invocation Message-ID: <20260811104229.72fdd928@gandalf.local.home> In-Reply-To: References: <20260811135537.GC544626@ziepe.ca> <1d669aca4ffee797b9c29215382444a5b23624b3.camel@infradead.org> <20260811142730.GG544626@ziepe.ca> X-Mailer: Claws Mail 3.20.0git84 (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-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX19dAleZhUOu5jMhgkH99lyj0Dn95BWTID4= X-HE-Meta: U2FsdGVkX1979J+Q3OdtvU+zN/hhYl9JQhI0wFYQuN1ZrCOyLwM835zzoagX5l163DZzohmxYfjMQMg9LMvXrD6bg3AeHd1TrLiR6S1r8L72HAN+v3XhoxZRX8xO+2I0Jc1dgxN+O60SUmzois9+y6MU9QJdwUAoXwKZYXZvgflOY5MkQGkqp/ZeTZ3GzgxqRZ0WF8S3WS8LB8o7TyvqBGXiA98/d9imuVuTVh0RKt7dphRhabMtXLx1CHkUp+8F6TrPt7w6fDOjixFfwzPAI0/VQK18sVl3nuIRCZ+fXGfIeFWakblsUYrcuLOfrE2v16Fx2y20k2tKyfUJUKu/Aa1kEnu9UsWEY7fVgeGUG4kiRo2q1nZuksArsq2JybJg X-HE-Tag-Orig: 1786459338-307469 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AEFF7100009 X-Stat-Signature: oxypg9f677wxwcpnaarkrfp38fcwugwo X-Rspam-User: X-HE-Tag: 1786459344-107451 X-HE-Meta: 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 Jrh4cfMc IPF3J7QHL1AS1nwwSldNTcVv/c7fbqfCrAlXJCqwAM3oVQpvsRKwJLOvKDJhQH9FvOedIOnPRV9zJdog= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 11 Aug 2026 15:33:18 +0100 David Woodhouse wrote: > > If might_sleep doesn't work sanely at all in preempt_rt then just > > globally turn it off? > > Turn might_sleep off? Or PREEMPT_RT? :) > > The RT maintainers are on this thread if you want to pick either of > those fights... that was not the course of action I chose to take. I guess the question is, what exactly is the reason for sleeping to be prohibited? In RT, sleeping is allowed in most context because most context are threads (like interrupt handlers and such). Now, you still can't sleep in NMIs and hard interrupt handlers that were not converted to threads, but I'm not sure that's the case here anyway. If the non_block_start() is just a big hammer to make sure things are fine in non-RT, it will likely still be fine in RT even though it may block and sleep. But what it blocks on are sleeping spin locks that likely would not cause an issue here if they didn't cause an issue in non-RT. Thus, perhaps something like this: if (ops->invalidate_range_start) { int _ret; if (!IS_ENABLED(CONFIG_PREEMPT_RT) && !mmu_notifier_range_blockable(range)) non_block_start(); _ret = ops->invalidate_range_start(subscription, range); if (!IS_ENABLED(CONFIG_PREEMPT_RT) && !mmu_notifier_range_blockable(range)) non_block_end(); ?