From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 E22C32D7D3A for ; Tue, 21 Apr 2026 10:15:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776766530; cv=none; b=Dwvk9tqCia+JGJL9fsajLsaDDZltfelKWqrY8IQsGX5q7KT/R3vQrrPob2nVTSNu9oPtt6kOzOeZ3qSZJdS7MlitS45m15M0zyAozNZHefaJMlXBJzY0AegfB45rgsuYNSkCJ5ZnVo+z5IX0wv+Bh3dubh9dcI9gVZAH+rdpR6c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776766530; c=relaxed/simple; bh=A/GL6Glyfl0ZlaaVOo7DG2U1pXhEuVuJgIt9YAbXXUM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GUo+ToJk66OkeIoxYSaCP/RL1nLR97PnUfn4GJi5EXgK/pcZwm0y7FnB2QuHmHjx86+cEdoPKxCy57/DTgp8FjoEfzgmc/NMhTn1Y32J2u8otZ3H9CngwlTxgHYbOXJwJxzX6tzj1Endb+7i2VNYS+3ppzm7lLgsRRokRa0ej1o= 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=qCsat0lf; arc=none smtp.client-ip=90.155.50.34 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="qCsat0lf" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=6VTyml2rkKvGCCL9WLwv3vpWAHAsWbCWLHCbHrD18+g=; b=qCsat0lf1XhVGkE5QQ6l59pOot Ejone6Ia4Db3lpd2f3ADrQTPvYgbgLETSMUksTcHWBPwo20BOinQdoI4z/aEoUsk/e/kxal66lb3j r6oaaTgSnigsAxutTGV42vRL2qH5K9rwfYN93jv8Eq16duIbkKQ/w0Enc3w4vCkdiyl7PGLQhiBxu WjcQm+ZHV+Lr+upDsW5Z8QwMdbgNR16LCI93g5k9p/ErhCDohoR7XjPKxWq3326BUmPz9KqJQXlhz rNAeGk27C7+GZ1qmr/txCD29uoh+DeQ8o7seCRS6nHmDMzRzTXtiwvnOW7WiXJlrY/I0uIqQwrN6B x3bS91FA==; Received: from 2001-1c00-8d85-4b00-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:4b00:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1wF88X-00000009wD9-40WF; Tue, 21 Apr 2026 10:15:22 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 50674300708; Tue, 21 Apr 2026 12:15:21 +0200 (CEST) Date: Tue, 21 Apr 2026 12:15:21 +0200 From: Peter Zijlstra To: John Stultz Cc: "Borah, Chaitanya Kumar" , willy@infradead.org, linux-kernel@vger.kernel.org, "intel-gfx@lists.freedesktop.org" , "intel-xe@lists.freedesktop.org" , "Kurmi, Suresh Kumar" , "Saarinen, Jani" , ravitejax.veesam@intel.com, K Prateek Nayak Subject: Re: Regression on linux-next (next-20260324 ) Message-ID: <20260421101521.GO3102624@noisy.programming.kicks-ass.net> References: <20260327163100.GL3738010@noisy.programming.kicks-ass.net> <20260327164353.GM3739106@noisy.programming.kicks-ass.net> <20260330195037.GW2872@noisy.programming.kicks-ass.net> <20260420130318.GD3102924@noisy.programming.kicks-ass.net> 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: On Mon, Apr 20, 2026 at 11:45:12PM -0700, John Stultz wrote: > So I tripped over this in my own testing today preping proxy patches, > bisecting it down to the same problematic commit 25500ba7e77c > ("locking/mutex: Remove the list_head from struct mutex"). > > Inteed it does seem related to ww_mutexes, as I can pretty easily > reproduce it with defconfig + CONFIG_WW_MUTEX_SELFTEST=y using > qemu-system-x86 > > Where the test will basically hang on bootup. *groan* indeed. This of course means no CI is running this thing :-( Anyway, yay for deterministic reproducer. Let me go prod at this.