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=-2.0 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 C36FBC74A35 for ; Wed, 10 Jul 2019 22:09:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 974FF21019 for ; Wed, 10 Jul 2019 22:09:54 +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="tvj7nWZT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727940AbfGJWJx (ORCPT ); Wed, 10 Jul 2019 18:09:53 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:59292 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726245AbfGJWJw (ORCPT ); Wed, 10 Jul 2019 18:09:52 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=YyhdUNqc+1DemkH/mFNcRWRYGtV6ZT58QmHsWfF+fSI=; b=tvj7nWZTgbw4gHPrUgwXWZGXZ ooryy+Kv8N/TYO33WSXlxLBltdW0qgv6qSk5M3fBVYumNzMHDyPbZYopJJyI5n8efu/6LfVjKzL+p Y/NfGGL/ZXhiJqfxIJU8lk2FcHraOmMPhgw8ulQu9aqqaLfmRZFF+A8O9CHR1tCGuQNiNxs/zBAgY BtDEpH7Hsovn993InHZyZ/S/1rLNnq7MTQa+GkVPN6dp9UHUL5+8JKg+RAOH+ndtztgIWbSqqqpoZ jc/zNIfduEECVlJkUm2/sv2jm3QEo8MsNeRLpAvgW33LANeh2UKfm+Wg+/H2ZRoma7xS0fri7ylvS kD8IBSJPQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1hlKmY-00016P-34; Wed, 10 Jul 2019 22:09:46 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id CEB57201247EB; Thu, 11 Jul 2019 00:09:43 +0200 (CEST) Date: Thu, 11 Jul 2019 00:09:43 +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: <20190710220943.GM3419@hirez.programming.kicks-ass.net> References: <20190710170057.GB801@sol.localdomain> <20190710172123.GC801@sol.localdomain> <20190710180242.GA193819@gmail.com> <47a9287d-1f02-95d5-a5cf-55f0c0d38378@gmail.com> <9219c421-0868-f97f-2d84-df48aed9f8a8@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9219c421-0868-f97f-2d84-df48aed9f8a8@acm.org> 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 Wed, Jul 10, 2019 at 02:23:39PM -0700, Bart Van Assche wrote: > As one can see in remove_class_from_lock_chain() there is already code > present in lockdep for compacting the chain_hlocks[] array. Similar code > is not yet available for the stack_trace[] array because I had not > encountered any overflows of that array during my tests. 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.