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 0BCB643E9DF for ; Wed, 1 Apr 2026 16:05:50 +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=1775059554; cv=none; b=ZKXephKeKu9nDu1bV3WzZ2mJxK0A+T7NEvQHozPWzusw6XoJYiNlgRR43Qwk3i04Inajx2PLBTEKirZjzjBhdI7lAkopYsRUQhyQO7E1uJjqT9lK9ZReoI5sXEhFbvk1YE2jjSEGRh3ffaseQplkYXt21WMKycBa3n7XmFYFtSI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775059554; c=relaxed/simple; bh=oB+lrARKT0dxZ01hzqQZRWakdvXCoRQGEvAp7ej+jxU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=N+DNPMNVqx4gfcgFEUQon1i6ej9QqkkLLbk/UV4I1JecOdBpKgabfdFLcFgyBbNG6MleBSXMkgPE3PiovwmCWfUShWGq8pBINO6sUUvbcBOLVBQX2vOLLEHqGHqIFrOxNstM+0VPo5RRTk3yEL5qMbsXGUE1reRGIJq7aZM7/qc= 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=f/DiQqIB; 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="f/DiQqIB" 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=oVjDQ6EWmS36gisg4QOLuAo/ep+4dMBdY4/8mKH1/Sw=; b=f/DiQqIBr5KmMmXsYDoot/kmM5 w/CErb1pj/UZr8gUS3CnnHpj62L56kgRHo6ez6dcCuCzuFzva2/xSInHsIycnxzVD3UXfdUBcGYtd u/CBPdPvTD4luVd1AJDr72VCa5IuugIEnpv7zeWROc61fmreYh3SP/r+9gA1bEW5Cdzn3RP1BBIbv ylnEXGFd0E8I3iowxWkAj5SCZjySOLz0NRa1ppS3YXI6PSTugz/kolimDNvSNCqfAZL5gqO4nf+66 HYDrGEQXi7U4WvlOZOQg3y65RO/QEJVV10/054Cm4w40hpU3MPUPGtV4vvOFHVQ4MTLe1fv8PkAd4 GWh91Wsw==; 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 1w7y4i-0000000AfSn-0GO0; Wed, 01 Apr 2026 16:05:48 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0075B3032D8; Wed, 01 Apr 2026 18:05:45 +0200 (CEST) Date: Wed, 1 Apr 2026 18:05:45 +0200 From: Peter Zijlstra To: Christopher Lusk Cc: linux-kernel@vger.kernel.org, mingo@redhat.com Subject: Re: [BUG] WARNING in perf_cgroup_switch: EVENT_FROZEN assertion during kthread sched-out Message-ID: <20260401160545.GX2872@noisy.programming.kicks-ass.net> References: 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 Wed, Apr 01, 2026 at 10:15:56AM -0400, Christopher Lusk wrote: > Hello, > > I'm hitting a WARNING in perf_cgroup_switch() on kernel 6.12.0 during > continuous syzkaller fuzzing. The assertion WARN_ON_ONCE(ctx->is_active & > EVENT_FROZEN) in __perf_ctx_lock() fires when the rcu_preempt kthread is > being scheduled out. > > Kernel: 6.12.0 (RHEL 10 build, no out-of-tree modules) Does this reproduce on anything recent?