From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 73144313D48; Tue, 23 Sep 2025 12:16:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758629803; cv=none; b=DqX6+MKGUUB+XV1Mf0j/qS3AkO3IqEksVoyd0jW1yzWPN97PeOfkh+FUxZvHSsBAEJxbFX23ypJNEuzAOtyBRDrDSkb+eq9HoVqPsplmM+bOzb19onU61/51IMpxIjr0QULWXhcUESWwq8bqWu9PVleG9OESq4YYz3ufxhf4c+8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758629803; c=relaxed/simple; bh=LpPwgkPOFFj4f6p46yUHv3+NqbNrx5FI55W7uiJ7e3s=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=Pe4LJw3VUdMsbKfwp14vIQSbyGIQRnCCUrUMdScCae5yZFUYnw7H5Am0t+rQFpxuy5YatGNxncVZkeSMdTzJA7FNoVW06kMCGXdhtwcKVO/h6tiYLbO4ne3T+Ld0ADX/NejaaYfdqPMyP9wQaDxgkN+Sh3MOzkxHGAYL1AdFt18= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YaY54zQw; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YaY54zQw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E23F0C4CEF5; Tue, 23 Sep 2025 12:16:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1758629803; bh=LpPwgkPOFFj4f6p46yUHv3+NqbNrx5FI55W7uiJ7e3s=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=YaY54zQwHVs+wWZOk4fmHWhRWqXMCJSxicNnD+pdINd2vl2XOOgqkxA1ZzeUexF7m LBPvqPCnbrSB2bdCakQHumwGVp3npdw9eISfjQ6ZvtnhfUq3XeVpcU9oLYrA2iZNWX Haty5AiIuOTXdpqDafSRyWpI/391FYAWEYCL8JrEqrVFwIxe0DtgUycBYxsvx+8+1G yhewcwMk9o3ourwOAm4sFl65oM30KGcBL8PQ7WnSwnvtiJAPg5nQOB1rWJ0LrEZpZK OQiT+azwPA6rI7GzTiIY6hcIsEK1DVe1QyBsVoripFZDQPEPoq1VaADo9N1gTbUtRB vzp0EzgrG58bA== Date: Tue, 23 Sep 2025 08:16:34 -0400 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, Masami Hiramatsu , Mark Rutland , Mathieu Desnoyers , Andrew Morton , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , Linus Torvalds , Josh Poimboeuf Subject: Re: [PATCH v2 2/2] unwind deferred/x86: Do not defer stack tracing for compat tasks Message-ID: <20250923081634.24ef8132@batman.local.home> In-Reply-To: <20250923104515.GF3419281@noisy.programming.kicks-ass.net> References: <20250827193644.527334838@kernel.org> <20250827193828.514833400@kernel.org> <20250923104515.GF3419281@noisy.programming.kicks-ass.net> X-Mailer: Claws Mail 3.17.8 (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 On Tue, 23 Sep 2025 12:45:15 +0200 Peter Zijlstra wrote: > Changelog seems to forget mentioning *why* we can't unwind compat. > > I'm sure I've seen compat FP unwind support at some point in this > series. Did that go missing somewhere? > > Also, these two patches are in the wrong order, first you enable things, > including compat tasks, and then you go 'whoopsie, no compats'. Sure, we can swap it. Yes, we had patches to support it, but they were a bit complicated and when I tested them, they didn't work. But then I also noticed that the current stack tracing didn't work on compat either. Instead of adding complicated code that wasn't working on my machine, I decided to remove the patches. But after I did that, I realized I needed to make sure it wasn't even tried, which is this patch. I'm not sure who needs profiling on compat code, and I figured we can not add the new deferred work to it if it's not needed. If in the future we need it, we can add it then. -- Steve