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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D5FA5C32793 for ; Wed, 18 Jan 2023 18:29:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229887AbjARS25 (ORCPT ); Wed, 18 Jan 2023 13:28:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229528AbjARS2x (ORCPT ); Wed, 18 Jan 2023 13:28:53 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E60EE23C79 for ; Wed, 18 Jan 2023 10:28:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1674066487; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Yc6aYGxEIFfDCIA/Zf5NYIcbIePQEIByP3E8Jqjy8zY=; b=d5ymuZBoOfhF+RXyrmq2CS6JldY0h58dyPVasodfsgnpIBBRJahDSAf6YvHqW0SQxJRfCz r75aoxxwpVJ+sNLc7yaWaNXwJVVhc2u9fp9zk/4yz788IX8r4NHkwAfux6vpph5SBVmssO yBh/QUnp/RUFIfQypEzsj/zNrX17+M4= Received: from mail-yb1-f200.google.com (mail-yb1-f200.google.com [209.85.219.200]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-310-EMexDfx3Mi2EZ1VvlFtP_Q-1; Wed, 18 Jan 2023 13:28:05 -0500 X-MC-Unique: EMexDfx3Mi2EZ1VvlFtP_Q-1 Received: by mail-yb1-f200.google.com with SMTP id k204-20020a256fd5000000b007b8b040bc50so36341197ybc.1 for ; Wed, 18 Jan 2023 10:28:05 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=mime-version:message-id:date:references:in-reply-to:subject:cc:to :from:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Yc6aYGxEIFfDCIA/Zf5NYIcbIePQEIByP3E8Jqjy8zY=; b=BsnsKlk347YyGyYdvoKVsKEBIQQWAEPnzH+NSjGpU5NV/mmm9sS8dcUFWkdzvcs8AP RoohjWLq240VIVxoesBfVNkPPhasvdB6jMriF19uLXNFcX3TZ+hWCkQU9gQGsl8Aw+CR Yxs4mbKgprbOpE6BeYKe8A7w3oKW3BuVdfkzmM/aNX/+f/rHsMvM2yBW5LwQCf57K5cp rfPnQOKFkdRwIM0UzD+XEJb7saq8n0R+kVtKs/n4Z8VHWGNXgCnxQNGGJabFieRKIuWg arkmBbrBoxhnR/PgHLw8svbvkrn+xGqnz6yGBY+5t96OwKkA2EODSs93oSRkCr1tgsgi DZJw== X-Gm-Message-State: AFqh2kodDRRitIOst2ooIuzk27//JlALWgH5kYUagH2mSNDsM/SEEGCg 2TNaAsgSj/Kp114vagBdewa/YlW5vfW3khIYwG6V8ag7EwV34Yd6HNaNeos18iSo1JdqohqRwqW 06h4PwAol6BpmDmKZxSxCPBQ7 X-Received: by 2002:a25:a2cf:0:b0:7b5:9a5b:74bb with SMTP id c15-20020a25a2cf000000b007b59a5b74bbmr6611940ybn.38.1674066484427; Wed, 18 Jan 2023 10:28:04 -0800 (PST) X-Google-Smtp-Source: AMrXdXu4nral7lgMvrs/RhImojO6xXvLZ4kNxpFDbnlDV6jH2tcgXmVSJfAkaLmhCf/fVt+EbOchmw== X-Received: by 2002:a25:a2cf:0:b0:7b5:9a5b:74bb with SMTP id c15-20020a25a2cf000000b007b59a5b74bbmr6611920ybn.38.1674066484187; Wed, 18 Jan 2023 10:28:04 -0800 (PST) Received: from vschneid.remote.csb ([154.57.232.159]) by smtp.gmail.com with ESMTPSA id s15-20020a05620a254f00b007056237b41bsm22719177qko.67.2023.01.18.10.28.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 18 Jan 2023 10:28:03 -0800 (PST) From: Valentin Schneider To: paulmck@kernel.org Cc: Wander Lairson Costa , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , "open list:SCHEDULER" , Thomas Gleixner Subject: Re: [PATCH] sched/deadline: fix inactive_task_timer splat with CONFIG_PREEMPT_RT In-Reply-To: <20230118181132.GF2948950@paulmck-ThinkPad-P17-Gen-1> References: <20230104181701.43224-1-wander@redhat.com> <20230110013333.GH4028633@paulmck-ThinkPad-P17-Gen-1> <20230110222725.GT4028633@paulmck-ThinkPad-P17-Gen-1> <20230118181132.GF2948950@paulmck-ThinkPad-P17-Gen-1> Date: Wed, 18 Jan 2023 18:28:00 +0000 Message-ID: MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18/01/23 10:11, Paul E. McKenney wrote: > On Wed, Jan 18, 2023 at 03:57:38PM +0000, Valentin Schneider wrote: >> > Given that this problem occurred in PREEMPT_RT, I am assuming that the >> > appropriate definition of "atomic context" is "cannot call schedule()". >> > And you are in fact not permitted to call schedule() from a bh-disabled >> > region. >> > >> > This also means that you cannot acquire a non-raw spinlock in a >> > bh-disabled region of code in a PREEMPT_RT kernel, because doing >> > so can invoke schedule. >> >> But per the PREEMPT_RT lock "replacement", non-raw spinlocks end up >> invoking schedule_rtlock(), which should be safe vs BH disabled >> (local_lock() + rcu_read_lock()): >> >> 6991436c2b5d ("sched/core: Provide a scheduling point for RT locks") >> >> Unless I'm missing something else? > > No, you miss nothing. Apologies for my confusion! > > (I could have sworn that someone else corrected me on this earlier, > but I don't see it right off hand.) > > Thanx, Paul Heh, I had a smidge of doubt myself, but since we've cleared this up: Reviewed-by: Valentin Schneider