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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 5CDC9C433FF for ; Tue, 13 Aug 2019 15:06:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 36041205F4 for ; Tue, 13 Aug 2019 15:06:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729894AbfHMPGy convert rfc822-to-8bit (ORCPT ); Tue, 13 Aug 2019 11:06:54 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60566 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726637AbfHMPGx (ORCPT ); Tue, 13 Aug 2019 11:06:53 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3893830EA1BA; Tue, 13 Aug 2019 15:06:53 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-255.rdu2.redhat.com [10.10.120.255]) by smtp.corp.redhat.com (Postfix) with ESMTP id 8F79580FD6; Tue, 13 Aug 2019 15:06:51 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <0000000000004c2416058c594b30@google.com> <24282.1562074644@warthog.procyon.org.uk> <20330.1564583454@warthog.procyon.org.uk> <22318.1564586386@warthog.procyon.org.uk> <3135.1565706180@warthog.procyon.org.uk> To: Dmitry Vyukov Cc: dhowells@redhat.com, syzbot , Eric Biggers , David Miller , linux-afs@lists.infradead.org, LKML , netdev , syzkaller-bugs Subject: Re: kernel BUG at net/rxrpc/local_object.c:LINE! MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <8012.1565708810.1@warthog.procyon.org.uk> Content-Transfer-Encoding: 8BIT Date: Tue, 13 Aug 2019 16:06:50 +0100 Message-ID: <8013.1565708810@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Tue, 13 Aug 2019 15:06:53 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dmitry Vyukov wrote: > > I meant that I don't know how to turn a tracepoint on from inside the kernel. > > This /sys/kernel/debug/tracing/events/rxrpc/rxrpc_local/enable in: > echo 1 > /sys/kernel/debug/tracing/events/rxrpc/rxrpc_local/enable > should map to some global variable, right? If so, it should be > possible to initialize that var to 1 statically. Or that won't work > for some reason? As I understand it, it's all hidden inside of tracing macros and ftrace infrastructure and involves runtime patching the code to enable tracepoints (they're effectively NOP'ed out when not in use). So, no, it's not that simple. I asked Steven and he says: trace_set_clr_event("sched", "sched_switch", 1); is the same as echo 1 > events/sched/sched_switch/enable So it can be done. Will syzbot actually collect the trace log? David