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 E253214A612 for ; Thu, 9 May 2024 15:30:27 +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=1715268629; cv=none; b=hcjABJdxwpC0RZTMMMisn5+oaoKODBIPffwT/CgYEGKoBwzg1DOL7IXvuXshayrzRnqXqc0+wvHNfUNFAo0l02j7Btjfr0SvTq3S7/CEQPNVkzbSBlnJ7LDiWExkIKGeQ3v4OqphUQW+QJttH330P+P/JlIPpl+AMz/dZcmOJ4U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1715268629; c=relaxed/simple; bh=UTqGM0dWpCz6nS63Q6iMVN9wJSByAgwNJAKBTDBd2bM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=afZBa9/RSBiqUfCcKo1vhyhdX5NTofowHWR7yY6kOMbdjfRGMvFruk71FAvXaiy5He82PwmUi7MXvAdfFBkd9yZ2gVkvCnvM44IM2B5JGKYh3C6M14UvbZ+sdVCKem+RL5XqmROKzLiHE8ctTMjr7qAKKb08I24gMQShuEV5F+Q= 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=C/T4oVm6; 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="C/T4oVm6" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1715268626; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=Hy/b3d3gFNZGN9o/TMf1nXsT/S7nrlG2+f6fAjptoCk=; b=C/T4oVm6gew2PPhag8b7eOEWmIyu69ghV59F1Po5xlginR9fU+Sa9MhHE0oaDguU3JvvlK NpGK5LWUWLGruCKg3boOKf2VGK1kRc2HzkkhaqUe0BGTT5gekD14zjw13VJS8ZKP3Rz0W0 BA8k5Xy67KDzLutQtOt1d/VWmwoKMh8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-378-lBH72HkKPEu-T6_GN-WWuA-1; Thu, 09 May 2024 11:30:24 -0400 X-MC-Unique: lBH72HkKPEu-T6_GN-WWuA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (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 mimecast-mx02.redhat.com (Postfix) with ESMTPS id 562671816ED2; Thu, 9 May 2024 15:30:23 +0000 (UTC) Received: from localhost (unknown [10.72.116.38]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 48D5220C5662; Thu, 9 May 2024 15:30:21 +0000 (UTC) Date: Thu, 9 May 2024 23:30:19 +0800 From: Baoquan He To: Rik van Riel Cc: akpm@linux-foundation.org, Vivek Goyal , Dave Young , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH] fs/proc: fix softlockup in __read_vmcore Message-ID: References: <20240507091858.36ff767f@imladris.surriel.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 On 05/09/24 at 09:41am, Rik van Riel wrote: > On Thu, 2024-05-09 at 11:52 +0800, Baoquan He wrote: > > Hi, > > > > On 05/07/24 at 09:18am, Rik van Riel wrote: > > > While taking a kernel core dump with makedumpfile on a larger > > > system, > > > softlockup messages often appear. > > > > > > While softlockup warnings can be harmless, they can also interfere > > > with things like RCU freeing memory, which can be problematic when > > > the kdump kexec image is configured with as little memory as > > > possible. > > > > > > Avoid the softlockup, and give things like work items and RCU a > > > chance to do their thing during __read_vmcore by adding a > > > cond_resched. > > > > Thanks for fixing this. > > > > By the way, is it easy to reproduce? And should we add some trace of > > the > > softlockup into log so that people can search for it and confirm when > > encountering it? > > It is pretty easy to reproduce, but it does not happen all the time. > With millions of systems, even rare errors are common :) > > However, we have been running with this fix for long enough (we > deployed it in order to test it) that I don't think we have the  > warning stored any more. Those logs were rotated out long ago. OK, thanks for the explanation. Acked-by: Baoquan He