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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 7FFE0C742AE for ; Fri, 12 Jul 2019 08:55:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 53EF921537 for ; Fri, 12 Jul 2019 08:55:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="pAshXTbk" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726106AbfGLIzx (ORCPT ); Fri, 12 Jul 2019 04:55:53 -0400 Received: from merlin.infradead.org ([205.233.59.134]:60688 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725877AbfGLIzx (ORCPT ); Fri, 12 Jul 2019 04:55:53 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.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:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=x8WbIHFyv0ABBFcrHAzlMJIMfoT3LVqQH9+jbFhqNOk=; b=pAshXTbk8185R9diOLyIbCIL9 JbNJ9pCeEAgagt55CojO1I8wE+7O9I6TanWMhj4EFNHc2jKM4eDy1W8LUxF4Dmiz4ddGYycbQPTPL RK4c5ge932bvIH+gvxt3NKbodqAv12cCai89jnXSZunX5oilhHFcESRKq+U79IvM1ELtchT6jLiFj mH3EAONPGzd4ePD5Fl378KNIdbb9aFAhofWHhaYk1f6BBt6CF/vKd5Uo1Em+JLCsWIe5g8xga3Som qBkDPQacDtIhtiG11UrHgxrM/RLtrgUNMjcjUJ6VCEZnK+W3VX8UCRtwSNdNcepB/z8ISQm3tejnp GDv6AIdqg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hlrL9-0003mf-9v; Fri, 12 Jul 2019 08:55:39 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 5CBD920120CB1; Fri, 12 Jul 2019 10:55:36 +0200 (CEST) Date: Fri, 12 Jul 2019 10:55:36 +0200 From: Peter Zijlstra To: Bart Van Assche Cc: Eric Dumazet , Ingo Molnar , Will Deacon , linux-kernel@vger.kernel.org, syzbot , syzkaller-bugs@googlegroups.com Subject: Re: BUG: MAX_STACK_TRACE_ENTRIES too low! (2) Message-ID: <20190712085536.GP3402@hirez.programming.kicks-ass.net> References: <20190710172123.GC801@sol.localdomain> <20190710180242.GA193819@gmail.com> <47a9287d-1f02-95d5-a5cf-55f0c0d38378@gmail.com> <9219c421-0868-f97f-2d84-df48aed9f8a8@acm.org> <20190710220943.GM3419@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 11, 2019 at 11:53:12AM -0700, Bart Van Assche wrote: > On 7/10/19 3:09 PM, Peter Zijlstra wrote: > > One thing I mentioned when Thomas did the unwinder API changes was > > trying to move lockdep over to something like stackdepot. > > > > We can't directly use stackdepot as is, because it uses locks and memory > > allocation, but we could maybe add a lower level API to it and use that > > under the graph_lock() on static storage or something. > > > > Otherwise we'll have to (re)implement something like it. > > > > I've not looked at it in detail. > > Hi Peter, > > Is something like the untested patch below perhaps what you had in mind? Most excellent, yes! Now I suppose the $64000 question is if it actually reduces the amount of storage we use for stack traces.. Seems to boot just fine.. :-)