From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) (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 737AC274670; Tue, 15 Jul 2025 12:34:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.14 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752582901; cv=none; b=Vq6iJMj128HoiG+kh85bnvJOdVUiEEfEUfx4DCXxzKbvC+xTVHXtsYbWvEmGNlDVxqd29AI5KOCHtqErIhhIq5rXsUkLminYngWLgmIXxCpalmxVH3+aSOm5ZtmuK+6nz4rDVkGPEroZ5k01+mnDOZdu8NCGaoP0Gm+m/EHyL/k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752582901; c=relaxed/simple; bh=+BZrdO9qK8EyMXdnS9svcH8zWBpti9CiTn7FyoJYg7k=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=L9uAS5lq4TLfHfRSYg7fANnFiUKQeC96qiBhurqlw+mVa6NFYVvQdJVd0mugK2tY3WdCf/5afSFtk0STLBP/RZYqSheOSNKgxRk5HU2BQLbgSF74e1dwMz6sO4CfVPf5bA+VqElXVRP2c9CVumi/JMBQ7M0GKzD4SF5HUxIXcjQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.14 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay02.hostedemail.com (Postfix) with ESMTP id 3E78F12DD02; Tue, 15 Jul 2025 12:34:55 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf09.hostedemail.com (Postfix) with ESMTPA id 9379420032; Tue, 15 Jul 2025 12:34:50 +0000 (UTC) Date: Tue, 15 Jul 2025 08:35:06 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: Steven Rostedt , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, bpf@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mathieu Desnoyers , Josh Poimboeuf , Ingo Molnar , Jiri Olsa , Namhyung Kim , Thomas Gleixner , Andrii Nakryiko , Indu Bhagat , "Jose E. Marchesi" , Beau Belgrave , Jens Remus , Linus Torvalds , Andrew Morton , Jens Axboe , Florian Weimer , Sam James Subject: Re: [PATCH v13 07/14] unwind_user/deferred: Make unwind deferral requests NMI-safe Message-ID: <20250715083506.01458000@gandalf.local.home> In-Reply-To: <20250715090955.GP1613200@noisy.programming.kicks-ass.net> References: <20250708012239.268642741@kernel.org> <20250708012358.831631671@kernel.org> <20250714132936.GB4105545@noisy.programming.kicks-ass.net> <20250714101919.1ea7f323@batman.local.home> <20250714150516.GE4105545@noisy.programming.kicks-ass.net> <20250714111158.41219a86@batman.local.home> <20250715090955.GP1613200@noisy.programming.kicks-ass.net> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: ct31gh6ghco7w9n1i68kjeconey74mg5 X-Rspamd-Server: rspamout07 X-Rspamd-Queue-Id: 9379420032 X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+owfZCLFT0H27JDc0RpGDEM9MNHAUJVLU= X-HE-Tag: 1752582890-436053 X-HE-Meta: U2FsdGVkX1/b+myhqa8kmYE2rBGF4M/NqgI07kl1Bila8O+AqF1RD6ppUI6loRMxrqoU+Y1NgSHLx49SY2kbAkNorGE5zIZSUezJ5OVwhtGMUHAFeUeGB+O9eazvlB7IrCgP1gYdEdEfZv+jdCZnZys2hZLMBgxrnhQnUNwfbFWb5KUbAXx/S3nHIf+NjwHgena/inUELnViQ+AwZnjQNAXavjOqNhLD/Glbs8nxLqcBHC27omqej/8B8I+7+pf1yV5/ZMxStTgRlmwsJSKK5HKKtYLmD+i8f+PBpofeqaDt9TRAeLTgLrYwlIwraWvZZlHbaR0WXytfQ+QjUhjGw9hlE8LOT6yQj1fZC7XDE9xd/2JHnHIEckrh2IEsFPiV On Tue, 15 Jul 2025 11:09:55 +0200 Peter Zijlstra wrote: > On Mon, Jul 14, 2025 at 11:11:58AM -0400, Steven Rostedt wrote: > > On Mon, 14 Jul 2025 17:05:16 +0200 > > Peter Zijlstra wrote: > > > > > Urgh; so I hate reviewing code you're ripping out in the next patch :-( > > > > Sorry. It just happened to be developed that way. Patch 10 came about > > to fix a bug that was triggered with the current method. > > Sure; but then you rework the series such that the bug never happened > and reviewers don't go insane from the back and forth and possibly > stumbling over the same bug you then fix later. > > You should know this. The bug was with actually with the next patch (#8) that uses the bitmask to know which tracer requested a callback. Patch 8 cleared the bit after the callbacks were called. The bug that was triggered was when the tracer set an event to do a user space stack trace on an event that is called between the task_work and going back to user space. It triggered an infinite loop because the bit would get set again and trigger another task_work! I can merge patch 8 and 10, but it still would not have affected this patch, and would have likely led to the same confusion. > > I'm going to not stare at email for some 3 weeks soon; I strongly > suggest you take this time to fix up this series to not suffer nonsense > like this. > Sure, I'll take a deep look at your review and work on the next series to hopefully address each of your concerns. Thanks! -- Steve