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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id BCFDBC4321E for ; Sun, 4 Dec 2022 16:34:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230050AbiLDQeU (ORCPT ); Sun, 4 Dec 2022 11:34:20 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230152AbiLDQeU (ORCPT ); Sun, 4 Dec 2022 11:34:20 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1C5B85F65 for ; Sun, 4 Dec 2022 08:34:19 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A9C9460EC6 for ; Sun, 4 Dec 2022 16:34:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A1DBC433D6; Sun, 4 Dec 2022 16:34:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1670171658; bh=TLnTE+kPVXMoDkxyS27j3MgUfr4eKLKaj3jN/XjRVJM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mQZ8taOm1ZDMNheNWTKnBG55XdMU+Ge5cyC0N07LkbZmNp2mXJZHT9Ha1yqSszTOz basEE8K0bEkfr0vWCmKln8HC+8MVMjanwScQ6k01xOm4+XBPB5YgXKkzOBKxJm+KAU vViV4Rwhid92QSFwXbSbIz/q+XI3m6CVDN4GH1Lo= Date: Sun, 4 Dec 2022 17:34:15 +0100 From: Greg KH To: Steven Rostedt Cc: akpm@linux-foundation.org, mhiramat@kernel.org, yujie.liu@intel.com, zhengyejian1@huawei.com, stable@vger.kernel.org Subject: Re: FAILED: patch "[PATCH] tracing: Free buffers when a used dynamic event is removed" failed to apply to 4.19-stable tree Message-ID: References: <167006641591124@kroah.com> <20221203173655.1b1b2fac@gandalf.local.home> <20221204111451.2741a499@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221204111451.2741a499@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Sun, Dec 04, 2022 at 11:14:51AM -0500, Steven Rostedt wrote: > On Sun, 4 Dec 2022 09:21:23 +0100 > Greg KH wrote: > > > > > 5448d44c3855 ("tracing: Add unified dynamic event framework") > > > > > > And this is mentioned below. > > > > > > [..] > > > > > > > If any dynamic event that is being removed was enabled, then make sure the > > > > buffers they were enabled in are now cleared. > > > > > > > > Link: https://lkml.kernel.org/r/20221123171434.545706e3@gandalf.local.home > > > > Link: https://lore.kernel.org/all/20221110020319.1259291-1-zhengyejian1@huawei.com/ > > > > > > > > Cc: stable@vger.kernel.org > > > > Cc: Andrew Morton > > > > Depends-on: e18eb8783ec49 ("tracing: Add tracing_reset_all_online_cpus_unlocked() function") > > > > > > > Depends-on: 5448d44c38557 ("tracing: Add unified dynamic event framework") > > > > > > ^^^ > > > > Did you just make up a new field? We have a documented way to show > > dependancies for stable patches, please let's not create a new one :( > > Ug, I've seen this tag used before: > > example: e3f0c638f428fd66b5871154b62706772045f91a > > And just assumed that was the method. I guess I should have looked deeper. > > > > > > > Depends-on: 6212dd29683ee ("tracing/kprobes: Use dyn_event framework for kprobe events") > > > > Depends-on: 065e63f951432 ("tracing: Only have rmmod clear buffers that its events were active in") > > > > Depends-on: 575380da8b469 ("tracing: Only clear trace buffer on module unload if event was traced") > > > > Fixes: 77b44d1b7c283 ("tracing/kprobes: Rename Kprobe-tracer to kprobe-event") > > > > Adding the "unified framework" seems like way too much for a stable > > patch, are you sure all of these are required and should be applied to > > 4.19.y? > > > > It's that balance between rewriting it to the bare minimum, which is not as > intrusive, but tested much less and may be even more buggy, to backporting > a larger change that has been verified by real world use cases. > > Or we just do not backport it. The bug will still exist, but you really > have to work hard to hit it. And because it's only controlled by privileged > users, maybe it's OK to just ignore it. I think I've seen only one report > of this issue in the last 10 years. > > Thoughts? Sasha backported this to 5.4 and newer without needing the full new feature to be added, so I think we are now ok. thanks, greg k-h