From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=0.3 required=3.0 tests=DKIM_ADSP_ALL,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA104C43441 for ; Sat, 24 Nov 2018 19:15:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46C44205C9 for ; Sat, 24 Nov 2018 19:15:51 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=natalenko.name header.i=@natalenko.name header.b="qmqhAm1Y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 46C44205C9 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=natalenko.name Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726176AbeKYGEy (ORCPT ); Sun, 25 Nov 2018 01:04:54 -0500 Received: from vulcan.natalenko.name ([104.207.131.136]:37914 "EHLO vulcan.natalenko.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725738AbeKYGEx (ORCPT ); Sun, 25 Nov 2018 01:04:53 -0500 Received: from mail.natalenko.name (vulcan.natalenko.name [IPv6:fe80::5400:ff:fe0c:dfa0]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by vulcan.natalenko.name (Postfix) with ESMTPSA id D560F47A67C; Sat, 24 Nov 2018 20:15:45 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=dkim-20170712; t=1543086945; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qU36QWKxefo84ZnAJ7PbSAPL4RuwqtNYWsDCd3cnAZ4=; b=qmqhAm1YTsSgzjUfbTnxDLo27rkWl4ytpv4pQ//eviWCYjNfKywD2pCRMh6lc3klJEzjMz ypBznQoT1hfFenC0SMJsG0MTmIsI7Okw8bx0bjpHLXiAWQIV6D/VZ/eQnf4XwQSRpuMGi0 1IRlU+b2p2YX2VDokYxnNZ7y3y1AsRY= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Sat, 24 Nov 2018 20:15:45 +0100 From: Oleksandr Natalenko To: Steven Rostedt Cc: "David S. Miller" , Sebastian Andrzej Siewior , Thomas Gleixner , Eric Dumazet , Dave Jones , netdev@vger.kernel.org, linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org, Nikolay Aleksandrov Subject: Re: WARN_ON() in netconsole with PREEMPT_RT In-Reply-To: <20181111210105.7f376c35@vmware.local.home> References: <20181111210105.7f376c35@vmware.local.home> Message-ID: X-Sender: oleksandr@natalenko.name User-Agent: Roundcube Webmail/1.3.8 ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=natalenko.name; s=arc-20170712; t=1543086945; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qU36QWKxefo84ZnAJ7PbSAPL4RuwqtNYWsDCd3cnAZ4=; b=QhdfbK6/KTDx8ma2SQFqFUzTXOohMoA1hctWC29n7DDo+aTFlUhb9+wQwEfvV/Gt6FaoSh uLusfjthqbbRQAW5+bQaKspEqmZE10sHdFyWEDP2n/Z17WTCcy0S2Ky7A3qKlyHjt5kQSl Xhm+Gpkfz2qW/BBxKohxG2GtyaXZXwU= ARC-Seal: i=1; s=arc-20170712; d=natalenko.name; t=1543086945; a=rsa-sha256; cv=none; b=A/qJelJEaQwKxOvfZ75US1x2lzBcHITKicLnYTP71/M5h6/7gG0qEtvZAaKTzGnCfxYkpV o6FDbeJzYGgU8wOhZpfVh1EA7iF6VdECxCuZqbKfe+uMmn1mA9mE6kQ73mVKA3iEFKKocD Es90VkqqJALbHrKv30UJR4vQXQsow20= ARC-Authentication-Results: i=1; vulcan.natalenko.name; auth=pass smtp.auth=oleksandr@natalenko.name smtp.mailfrom=oleksandr@natalenko.name Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi. On 12.11.2018 03:01, Steven Rostedt wrote: > On Sun, 11 Nov 2018 21:16:00 +0100 > Oleksandr Natalenko wrote: >> Oh, I see that write_msg() calls netpoll_send_udp() under >> spin_lock_irqsave(), but in PREEMPT_RT this, AFAIK, does not disable >> interrupts. >> >> So, the real question here is whether the interrupts should be indeed >> disabled. And if so, -rt should replace spin_lock_irqsave() call there >> with what? local_irq_save()? and get rid of the warning? >> > > Why do we care if interrupts are disabled with PREEMPT_RT here? I don't know, if you ask me. But the check was added intentionally with c9fd56b34efd0, so the author had definitely something on his mind. Cc'ing him. > printk() itself has a lot of issues with PREEMPT_RT that we are working > on dealing with. Right now netconsole is actually at the end of that > todo list. OK, I see. -- Oleksandr Natalenko (post-factum)