From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 0061D38DC7 for ; Mon, 16 Sep 2024 10:38:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726483118; cv=none; b=TvvQRamnTgQxMkqlm9K0fr3uqDilI6/0p2p2nvUUPsTJOwiMoFKQzuNGadndNT8JLaub9wQ0oU/a8/kaMEGxwuRbclGikDfhEvlh8+ErJm6D/+YWsGNzO5nPIfxRBRqmtake9vwFwmVA/2oBB4DRLQuq6hNnRSzGA2Ro0B/D56s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1726483118; c=relaxed/simple; bh=qjNa3UtU8uCaSWy+UerRzf1K9Z0cHIBE+rP3Q7Oi7rY=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EVfaTokSMbfPKOfo9s6zQyN3l/SIPXCSOAYFspHWnqTdPiuGh206DYIKAvLXJUUrDBJUCY75vzjK65GhEezybpXnYBJwfsmSq2RmxpLlgeHHwZ/6/LItfPkomDyx77QIpLSNQiYSUq0C+eN4+KZMZwOzMKJd45MQ7Uc0X+sMKfs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=O9Mk1PYS; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="O9Mk1PYS" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1726483114; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TFuK5S8ppIHmZYG3Axev2zHBowrYvgWSkbnTKV3dF9s=; b=O9Mk1PYSYWK4QAGiGqNyBp9LcuQN95l9JgG6tcdMwm2IAq+EY6J/auEuBmdBWDGcWT4gDB 5PyOBPbWTjZRtSt7XIIUwB4VFF1O+t2fKVPRdZB0JJ+vB1LAojabt6m56i4bX7NWboE/B/ y96wlAr2yoqc+0VSsFqZVBss1Cpgh+o= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-650-lhl6jNH1ORazlwaAqRgEWg-1; Mon, 16 Sep 2024 06:38:31 -0400 X-MC-Unique: lhl6jNH1ORazlwaAqRgEWg-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4A4DE19560AB; Mon, 16 Sep 2024 10:38:29 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.82]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id EE06D195605A; Mon, 16 Sep 2024 10:38:24 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Mon, 16 Sep 2024 12:38:16 +0200 (CEST) Date: Mon, 16 Sep 2024 12:38:11 +0200 From: Oleg Nesterov To: Steven Rostedt , Masami Hiramatsu , Catalin Marinas , Will Deacon , Puranjay Mohan , Mark Rutland , Mark Brown , Kalesh Singh , chenqiwu Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: arm64: stacktrace: WARN_ON(state->common.pc == orig_pc) in kunwind_recover_return_address() Message-ID: <20240916103811.GA14111@redhat.com> References: <20240916102741.GA13899@redhat.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: <20240916102741.GA13899@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Ah, sorry for the noise, I looked into the wrong tree, missed the recent c060f93253ca ("arm64: stacktrace: fix the usage of ftrace_graph_ret_addr()") On 09/16, Oleg Nesterov wrote: > > I don't know the details but people report that > kunwind_recover_return_address() hits this warning. > > I know absolutely nothing about arm64 or kernel/trace/fgraph.c, but at > first glance this code looks broken: > > kunwind_recover_return_address: > > ... > > orig_pc = ftrace_graph_ret_addr(state->task, NULL, > state->common.pc, > (void *)state->common.fp); > if (WARN_ON_ONCE(state->common.pc == orig_pc)) > > ftrace_graph_ret_addr: > > ... > > if (!idx) > return ret; > > > given that kunwind_recover_return_address() passes idx == NULL to > ftrace_graph_ret_addr(), it should always return ret == state->common.pc ? > > > Perhaps this connects to 29c1c24a27 ("function_graph: Fix up ftrace_graph_ret_addr()") > and I have no idea if something like the patch below makes any sense. > > Oleg. > > --- a/arch/arm64/kernel/stacktrace.c > +++ b/arch/arm64/kernel/stacktrace.c > @@ -106,7 +106,8 @@ kunwind_recover_return_address(struct kunwind_state *state) > if (state->task->ret_stack && > (state->common.pc == (unsigned long)return_to_handler)) { > unsigned long orig_pc; > - orig_pc = ftrace_graph_ret_addr(state->task, NULL, > + orig_pc = ftrace_graph_ret_addr(state->task, > + &state->task->curr_ret_stack, > state->common.pc, > (void *)state->common.fp); > if (WARN_ON_ONCE(state->common.pc == orig_pc))