From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 EB34B2EF646; Thu, 30 Oct 2025 09:07:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761815252; cv=none; b=OGtwmaS4rGrvaRSB4p8eDVZpqMbYGIIZvHYeXalSCiIq9woAknUMV9becgsw8z4zNC4poyPJNIDKe/F9JJbmXJJv9tgivGS7sGoLRZSZxC0gZ2LnL7tyiSZWmOHxjYEkadvKEfCGp4YfnpVcaWyJGTymscxMOkaExk2okdx2XQE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761815252; c=relaxed/simple; bh=l1viRMC/UmwSuDDuvBE2zGgXvumdL/Ls7gVexkoy3K4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=j2xxlpBgSsowXMlmyxipY9/Ht1oAQrxo8Yux6K4OdReK55OJxB+xZqUZLadHoKEanFkx9QSWmgq9uBTD41KeUkHSTW2Xj3LVkst20KrjoC67XUjjiggMK7TgXWLqWoYih/pExB/ZNMMGyDvEFJPxRy1Fs2BV4zDP78KJHu2g3gI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=NyQmXPBW; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="NyQmXPBW" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=c2jqJvelZ1hYmz7asbMfIdSEjayi1eF7SkgIc3nH9G8=; b=NyQmXPBWuzXksesCUhML6S47F7 d4sh5asusrkHqeWZdIZBKm3lARUaHgSkqQ2jjpmoF5lHUEe/f4khSkrnTWJNRswo4N27Cufmc2KKy 9oOTPwWHTIVdZOu+iMiPL/4MxAgcw7+ig4N5EKdrnZvZaarohqH3bCqC1qUUR1iIHUZ3vF5ydAzbw LGrOGZUZfaaEHEosbbBDZl7uPgkKsJaaCDV/Wx/MaQqEzfwE9dZ3oN+MCQekzSlz1tfpXZbLH05vc x4/b5LJsc3OYPsrJJHDb5SrqGber647sJbn3be3d6mYsGSs83updmcgM74m7qnSk9D/p7RMiUPKbK jFqxFuTw==; Received: from 77-249-17-252.cable.dynamic.v4.ziggo.nl ([77.249.17.252] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vENl3-00000008jZI-0NhC; Thu, 30 Oct 2025 08:11:45 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id AE094300343; Thu, 30 Oct 2025 10:07:15 +0100 (CET) Date: Thu, 30 Oct 2025 10:07:15 +0100 From: Peter Zijlstra To: Mark Brown Cc: tj@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, longman@redhat.com, hannes@cmpxchg.org, mkoutny@suse.com, void@manifault.com, arighi@nvidia.com, changwoo@igalia.com, cgroups@vger.kernel.org, sched-ext@lists.linux.dev, liuwenfang@honor.com, tglx@linutronix.de Subject: Re: [PATCH 07/14] sched: Fix do_set_cpus_allowed() locking Message-ID: <20251030090715.GQ3245006@noisy.programming.kicks-ass.net> References: <20250910154409.446470175@infradead.org> <20250910155809.103475671@infradead.org> <29d7b92b-594e-4835-9dd3-3c9e2b02ada3@sirena.org.uk> Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <29d7b92b-594e-4835-9dd3-3c9e2b02ada3@sirena.org.uk> On Thu, Oct 30, 2025 at 12:12:01AM +0000, Mark Brown wrote: > On Wed, Sep 10, 2025 at 05:44:16PM +0200, Peter Zijlstra wrote: >=20 > > All callers of do_set_cpus_allowed() only take p->pi_lock, which is > > not sufficient to actually change the cpumask. Again, this is mostly > > ok in these cases, but it results in unnecessarily complicated > > reasoning. >=20 > We're seeing lockups on some arm64 platforms in -next with the LTP > cpuhotplug02 test, the machine sits there repeatedly complaining that > RCU is stalled on IPIs: Did not this help? https://lkml.kernel.org/r/20251027110133.GI3245006@noisy.programming.kick= s-ass.net