From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) (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 A413D145348; Thu, 17 Jul 2025 16:38:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.17 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752770327; cv=none; b=ahisBP7GdpDfBbd8kcR6J5f3DAk4ezqcyGavO3E5dvWokNWnuQ+QSnfgAbDA3Qu2neFlvNSKDBI9jKtRlfrYdL5A52agnnzrW3I5fpF/GDN84As57ZlkjA2nhK9HtwT5G8zGfF/XUIUOpW7WC7i1EFyNczV7TayZ6AmwnoIgYzA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752770327; c=relaxed/simple; bh=/lWi3pXaJ3llT/utRyZVcTX6L5mZifX69h5Q13eMmJ4=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=d0AFOx7rsyeTD0JyEgaoIjYSJtJxJSpU2a1Abq5GrnEfEvjXG/FXqqIsLiRkyJsyeVeMLJ11eQ59dbYl4pDXkEIo3n7583qW8uJUxpLbEaoz8cL7dBh00jvZRLhTbuoaCXtB8WuW4z5Sw3KiK3vQZIOFxFPG5n8mXJK2MJSPoO4= 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=216.40.44.17 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 omf10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 86DFB1A017A; Thu, 17 Jul 2025 16:38:41 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf10.hostedemail.com (Postfix) with ESMTPA id 74CAE32; Thu, 17 Jul 2025 16:38:36 +0000 (UTC) Date: Thu, 17 Jul 2025 12:38:35 -0400 From: Steven Rostedt To: "Paul E. McKenney" 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 , Peter Zijlstra , 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 v14 09/12] unwind deferred: Use SRCU unwind_deferred_task_work() Message-ID: <20250717123835.21c8aa89@batman.local.home> In-Reply-To: References: <20250717004910.297898999@kernel.org> <20250717004957.918908732@kernel.org> <47c3b0df-9f11-4e14-97e2-0f3ba3b09855@paulmck-laptop> <20250717082526.7173106a@gandalf.local.home> <41c204c0-eabc-4f4f-93f4-2568e2f962a9@paulmck-laptop> <20250717121010.4246366a@batman.local.home> 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 X-Rspamd-Server: rspamout04 X-Rspamd-Queue-Id: 74CAE32 X-Stat-Signature: xay1j81jcwor5ab8f19ohqmfyxetzg5p X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+dwEPDopII2FDU0xpnvkJQH8Cc23zvuzs= X-HE-Tag: 1752770316-666472 X-HE-Meta: U2FsdGVkX19l5YJ+we3bRDbWCryF5sp2t3YoXG0e5O1vVjxoXf4mqiiSkhzgpVLZDmdboRShCD/D/VyDiG57trD6Jp6HNNoJM856H4WPxuif7BgZyD/wMACwGw+4KUg7qeeIq3TVxQg2hQNEAbjbDLtoeMBM2WPU5GgXATtYBl+mTqaGqhkO17DOlxS5+9JOyDc065n+WbMh7SmDplrlFWl9s20KM8MXT5ZeP6US6vo8zYSMBzuskVQ4TNIJb0F+eFiHtzZB0BBgQDI7BKISqFPM9z3DPDqIwN8SfG6g1+g578MFpDbYOjO0OOmP4OXa3sMIf67/vWq1HwPKj6fUHhbroXJAtUAi On Thu, 17 Jul 2025 09:27:34 -0700 "Paul E. McKenney" wrote: > > Two, I'm still grasping at the concept of srcu_fast (and srcu_lite for > > that matter), where I rather be slow and safe than optimize and be > > unsafe. The code where this is used may be faulting in user space > > memory, so it doesn't need the micro-optimizations now. > > Straight-up SRCU and guard(srcu), then? Both are already in mainline. > > Or are those read-side smp_mb() calls a no-go for this code? As I stated, the read-side is likely going to be faulting in user space memory. I don't think one or two smp_mb() will really make much of a difference ;-) It's not urgent. If it can be switched to srcu_fast, we can do it later. Thanks, -- Steve