From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3FAA542982F for ; Tue, 28 Apr 2026 14:12:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777385530; cv=none; b=BgWJuCKIsxoOOepd0kZt1R5utTvLhBCNF1/556hOUtEzzBb9NdZNPjHQf9dIwPeGPhklIKo/mCKZLbxFbMyNmEjQAA+DCXb9xFRdDRZ9gS68GRiUbrmUgaDCFUZ72o9rtlmMFJLh1HgUfR31gNJnCMxA7wxSzCi0pdycP/IoLCs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777385530; c=relaxed/simple; bh=7iMlmt/hLF9HoZFooJKJml0LDLHD4uk5wBmxsr3Z0lA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ZzTmO/Ey3PvqFI8y1RWumxOGCKNFlMQHN5lYqe/Ea22Sh+EK6+FC8GIGKCvcv+YxAF1as7O8pdwT23ToMJ/98bLhRDHF23cUMEIDCMzffsZAFalIJvGGATHZ0Z8oxpB0UEeVthKC8MFFMzARjWXlaSjQsDB4nCCjksWj/J22x5g= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.17 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf16.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay09.hostedemail.com (Postfix) with ESMTP id CF62C8693A; Tue, 28 Apr 2026 14:11:58 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf16.hostedemail.com (Postfix) with ESMTPA id 4103520016; Tue, 28 Apr 2026 14:11:55 +0000 (UTC) Date: Tue, 28 Apr 2026 10:12:09 -0400 From: Steven Rostedt To: K Prateek Nayak Cc: Andrea Righi , Ingo Molnar , "Peter Zijlstra" , Juri Lelli , "Vincent Guittot" , Dietmar Eggemann , Ben Segall , Mel Gorman , Valentin Schneider , Christian Loehle , Koba Ko , Felix Abecassis , Balbir Singh , Joel Fernandes , Shrikanth Hegde , Subject: Re: [PATCH 1/6] sched/fair: Use guard(rcu) for sched_domain RCU sections Message-ID: <20260428101209.58006c27@gandalf.local.home> In-Reply-To: <0882ce78-a51f-4317-a1b4-624e39e65507@amd.com> References: <20260428051720.3180182-1-arighi@nvidia.com> <20260428051720.3180182-2-arighi@nvidia.com> <0882ce78-a51f-4317-a1b4-624e39e65507@amd.com> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: br5jn1ng1ayjicnbpcaam7w4bfcfmbug X-Rspamd-Server: rspamout02 X-Rspamd-Queue-Id: 4103520016 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+P0qGUDfc9S27cZTHRdSJDF54h+thLE18= X-HE-Tag: 1777385515-20678 X-HE-Meta: U2FsdGVkX1/XUcBNf+FNV10aHv1GN0zQmckHHc1PR3fQsLuKVwSW40eh/9fD4wc8wTLm2s6dPQfjgthWRy4TZdWo2MwV6ZIvViync3RDJ1x7S+R70QCIZGF3gftL2JfyCGGlE+SFIbi4fzZmUQQJ998AMG8CuuGR6Bcqzv5oDbK2QX5C9fFNZJY6HnxTZ4C0Qpo2E0Qu5n1xic/iQh5zhEKDo8pDjg6WEGp0hhTAulW9U1Wk5dPp9rAnoEbrp+x6xC98C9sCCUw0Bh1sepCvi0DXtAv3iuJJcv/zC1hKsE986Dj3jroCP2M7AL/59TA5uqqdxR065gk4pG8OpbXYdOrjkI1KCdyp On Tue, 28 Apr 2026 14:03:59 +0530 K Prateek Nayak wrote: > > - if (rq->nr_running >= 2) { > > - flags = NOHZ_STATS_KICK | NOHZ_BALANCE_KICK; > > - goto out; > > - } > > - > > - rcu_read_lock(); > > + guard(rcu)(); > > and since this is only called from: > > sched_tick() /* IRQs disabled */ > sched_balance_trigger() > nohz_balancer_kick() > > with IRQs disabled, we can get rid of that rcu_read_lock() entirely. Then we need to add a lockdep_assert_irqs_disabled() here too. -- Steve