From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 D235C1C27 for ; Sat, 9 Nov 2024 02:05:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731117915; cv=none; b=oXHxqXWh+hZXC1FDCL0i2xot1e94cXRP0BhXM1vp6ooWtXRL1shF3t0n483kk9ZzYRtKZ3gqY5SmcuSsLfw0lvuDDaQgLX9qt0IIyXhQwXYUcxyTPu+D/a0EDZGzwPOhEuf8S+4+BBfK9dhp94tpfDAqzftsRqsHyLBqNhhM1xk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731117915; c=relaxed/simple; bh=oHDnLhe79l2GGcoFm13Qr6MszLy/IqdJy1F39Si0m0g=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=WymJaPzfoDfdeoLXYGX+bjDspbtREQVZNNPcmKuXBiUtEx8l0oBCmDpUiROt9XVIX0q4Og+Dx2IbSJO+maUyla48ueWsRrRZe3jmQiUjPLJbwRJtpLsCGnzYW0k6oLAt68WaSwuFhgSnpHyaXTQpj7X7etAihyUD1BKog8VHQcM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=RPDcb0P+; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="RPDcb0P+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48F80C4CECF; Sat, 9 Nov 2024 02:05:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731117915; bh=oHDnLhe79l2GGcoFm13Qr6MszLy/IqdJy1F39Si0m0g=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=RPDcb0P+HICuQdMVfIz9NpkU9SdL2m+8KYvyqDXqf+SonFhPbjMjH9CO/KS2hKFvp k2MFn7LBRcA4IGyahZ/XEg1i0CRnvzMnAkCYz3s2nnrDxu13xFImTCurbNZs39LF7Y 2XLuX82FyvtsY1EcmoOCYKBUgE0+VHWnE7mOC/X6OJUG74ewAePKNWVfmvOKIpbNj2 mtdaEJmiIP50OW9feY5Mq37OaDyHBuz7k6RFGgUavcreWUIo2n8DiiPNDPO7ff5l7r hdZEAtQ56ZcIYrmuJF77vN1mkjXLDqfBKWc0K5IxG0dElHd2ZDcWZVWGMp4kklobCA +WGYREON3aUaQ== Date: Fri, 8 Nov 2024 16:05:14 -1000 From: Tejun Heo To: Changwoo Min Cc: arighi@nvidia.com, void@manifault.com, changwoo@igalia.com, kernel-dev@igalia.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] sched_ext: add a missing rcu_read_lock/unlock pair at scx_select_cpu_dfl() Message-ID: References: <20241109015420.170729-1-changwoo@igalia.com> 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-Disposition: inline In-Reply-To: <20241109015420.170729-1-changwoo@igalia.com> Hello, On Sat, Nov 09, 2024 at 10:54:20AM +0900, Changwoo Min wrote: ... > diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c > index 6ff501a18b88..830a21d666e9 100644 > --- a/kernel/sched/ext.c > +++ b/kernel/sched/ext.c > @@ -3320,9 +3320,11 @@ static s32 scx_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, > if (static_branch_maybe(CONFIG_SCHED_MC, &scx_selcpu_topo_llc)) { > struct sched_domain *sd; > > + rcu_read_lock(); > sd = rcu_dereference(per_cpu(sd_llc, prev_cpu)); > if (sd) > llc_cpus = sched_domain_span(sd); > + rcu_read_unlock(); Shouldn't RCU critical section cover the places where llc_cpus is deref'd? Thanks. -- tejun