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 8522742F54F; Mon, 2 Mar 2026 17:37:36 +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=1772473056; cv=none; b=P+2ulbXPojJ4IXjrWyU8EMEGbrUVspFUSXw/Q6SaCwLQfwZKy34HE5ddmebGytbXhW3/yvoek+5C1F2Kd6dEfKIbzesoBuJKbDtrnq5x+iqivoPwZ9Aw3AVGwVpBICkNort5kGshLNuPDrwvNzHJPzXAVkyUXB/V0r/l6M92lt0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772473056; c=relaxed/simple; bh=dRB0F4V6ayCiHSRIZ6hMdlNv3etVugXHS4j3fir50pw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mnoBYbvH/nSxNqtHSrsnQxinhSqz1FLmO/tnFCZNCQEFstDc8ZjZr+ywTfIozWyCIdnPLoMWU3sGVKBzIQdRIHAcRT76QPHimmwZv6ThuBfKXQpfRBs9bO4/vpqjjg6yFY2klNoc0Zjk4KIjy0ZKYXHKswdHRww2w4rOVv8HH8w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=deygbcZZ; 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="deygbcZZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E133BC2BC87; Mon, 2 Mar 2026 17:37:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772473056; bh=dRB0F4V6ayCiHSRIZ6hMdlNv3etVugXHS4j3fir50pw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=deygbcZZHQ0tLbWuge7w1YrRcKUtMT46TzMv0o50uOLUvUgpmjxMJwqEAFaxBrWTW 1t4gqvrfHS0jtvW2bXLtIgz/55hT5BEr9WmWlW6W4cD5naVMpxH1PGRKea3t/oBuZh WI8jR2cJoGP+tyPEzryvqgSVjWFB564m6KNwYAVrMpvSKlPAQBE0h6aY14tnt3SN/+ 7FOzbO0zYuK64JL+AgoQ8GV2OHREkjMxDZQbqcCxqewPfbc0hEs4fh32ixFUbZdKu5 uWJGl4wR6pqj0dfGPwAwbcZHSuiCtzag8pM1PpnoiO3sy79Vjg/hCGNffz8WdPNnV5 gky/6ZMqzUJ6A== Date: Mon, 2 Mar 2026 12:37:24 -0500 From: Sasha Levin To: Steven Rostedt Cc: Zw Tang , paulmck@kernel.org, peterz@infradead.org, mhiramat@kernel.org, jiangshanlai@gmail.com, mingo@redhat.com, acme@kernel.org, namhyung@kernel.org, rcu@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, bigeasy@linutronix.de, ast@kernel.org, boqun.feng@gmail.com, mark.rutland@arm.com Subject: Re: [BUG] RCU stall / hung rcu_gp: process_srcu blocked in synchronize_rcu_normal triggered by perf trace teardown on 7.0.0-rc1 Message-ID: References: <20260302133615.2304836-1-sashal@kernel.org> <20260302112545.51f7e100@gandalf.local.home> Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260302112545.51f7e100@gandalf.local.home> On Mon, Mar 02, 2026 at 11:25:45AM -0500, Steven Rostedt wrote: >On Mon, 2 Mar 2026 08:36:13 -0500 >Sasha Levin wrote: > >> This response was AI-generated by bug-bot. The analysis may contain errors — please verify independently. >> >> ## Bug Summary >> >> This is an RCU stall and hung task deadlock on 7.0.0-rc1, triggered by perf trace teardown under perf interrupt storm conditions. The perf subsystem's tracepoint unregistration path now blocks on SRCU (tracepoint_srcu), which in turn blocks on RCU grace period completion, creating a cascading stall when RCU progress is delayed by perf NMI interrupt storms. Severity: system hang (multiple tasks blocked >143s, eventual complete stall). > >Hmm, this analysis corresponds nicely to what I was thinking when looking >at the stack dumps, but it gives a bit more details than I would have. Thanks for the feedback! I'll finish fine-tuning this script, and publish it in a day or two :) -- Thanks, Sasha