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 smtp3.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 62BE9E94617 for ; Mon, 9 Feb 2026 22:56:38 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id 148A360C28; Mon, 9 Feb 2026 22:56:38 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id InZJ9P9WRp7B; Mon, 9 Feb 2026 22:56:36 +0000 (UTC) X-Comment: SPF check N/A for local connections - client-ip=140.211.166.142; helo=lists1.osuosl.org; envelope-from=intel-wired-lan-bounces@osuosl.org; receiver= DKIM-Filter: OpenDKIM Filter v2.11.0 smtp3.osuosl.org 3FEAF60B36 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osuosl.org; s=default; t=1770677796; bh=oXcdE+dCCg1DeJ80lcF+E7Xz9tNNb1S/uNq8kkMlQg4=; h=From:To:Cc:In-Reply-To:References:Date:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=Tqz2OKIBiSwvmH0OKfdGb4MTIXWTswZFyvQPphD5xyZKIDOZ91VMsTQMhFDP3boDY meBe9fmr9Z+P9g8rzSc4bi3gylGcBycY4aWQ/7Sn4h0jXsdrWCvSH2i0odLVaf5y0p +F4hV5l+w7wd/jf5bqvjzl5KFHvchH3ZFTLHQnzdJehXjH7ZhsPMaZjYWw7bzBT2tJ eut2j6+ZY7KvN8XIPX8yIzAjupXfAP0yxqvCFVxwLoVrBiQd1dUgxyyAKZMLYetxA6 q+bFbXbURnSTLIsEJfr3xJCxEP/clgsKYsIYHjd8MIiHUN7Vx8lI85TimvHT/QT+XZ O+x0X7249jP3A== Received: from lists1.osuosl.org (lists1.osuosl.org [140.211.166.142]) by smtp3.osuosl.org (Postfix) with ESMTP id 3FEAF60B36; Mon, 9 Feb 2026 22:56:36 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) by lists1.osuosl.org (Postfix) with ESMTP id 2248EF2 for ; Mon, 9 Feb 2026 22:56:35 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 06F3F4026E for ; Mon, 9 Feb 2026 22:56:35 +0000 (UTC) X-Virus-Scanned: amavis at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavis, port 10024) with ESMTP id UVYYXm6BLnn8 for ; Mon, 9 Feb 2026 22:56:34 +0000 (UTC) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=2600:3c04:e001:324:0:1991:8:25; helo=tor.source.kernel.org; envelope-from=tglx@kernel.org; receiver= DMARC-Filter: OpenDMARC Filter v1.4.2 smtp2.osuosl.org 5987F40249 DKIM-Filter: OpenDKIM Filter v2.11.0 smtp2.osuosl.org 5987F40249 Received: from tor.source.kernel.org (tor.source.kernel.org [IPv6:2600:3c04:e001:324:0:1991:8:25]) by smtp2.osuosl.org (Postfix) with ESMTPS id 5987F40249 for ; Mon, 9 Feb 2026 22:56:34 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 138A760008; Mon, 9 Feb 2026 22:56:33 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A334C116C6; Mon, 9 Feb 2026 22:56:32 +0000 (UTC) From: Thomas Gleixner To: Joe Damato Cc: intel-wired-lan@lists.osuosl.org, Tony Nguyen , Przemek Kitszel , netdev@vger.kernel.org In-Reply-To: References: <87v7g8zv2o.ffs@tglx> Date: Mon, 09 Feb 2026 23:56:29 +0100 Message-ID: <87a4xhbk6a.ffs@tglx> MIME-Version: 1.0 Content-Type: text/plain X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770677792; bh=trw4gZg3u5netF1WY9Edyh3HqtUonFyD0wBYk7S4QxA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=r5kEeuHy3lfzpJAInS+BRw3PmZL6CXsXz14Urxz8g6Z5va/QaUMHUDabPMIGZ+oYl F2tdFDYonNJcgd172JM6S7+/wpqy8viblrbx9bSbjsspn5MZUQa22gKskjS+mNZZu/ fEVmEEhQSRGh2sV5RjCGbVzSNRAeQukzkotxIEahoybo78CIOrPSwok3BFQ/wiJC70 MI/p/2hl38F+smbf6l/zw+2brV89ESzA0VtL+phuesuY+dJX/HUHtHikHIA1eCUfZq gewriuu0KzRb+bIJlXW8EJ48pn7DnAM40x70avjyMyJYDb3CnvimyA4pzCQiynhKQh rMHmHEx+jjP8A== X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dmarc=pass (p=quarantine dis=none) header.from=kernel.org X-Mailman-Original-Authentication-Results: smtp2.osuosl.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=r5kEeuHy Subject: Re: [Intel-wired-lan] i40e: Fix preempt count leak in napi poll tracepoint X-BeenThere: intel-wired-lan@osuosl.org X-Mailman-Version: 2.1.30 Precedence: list List-Id: Intel Wired Ethernet Linux Kernel Driver Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-wired-lan-bounces@osuosl.org Sender: "Intel-wired-lan" On Mon, Feb 09 2026 at 14:07, Joe Damato wrote: > On Sat, Feb 07, 2026 at 11:50:23AM +0100, Thomas Gleixner wrote: >> Using get_cpu() in the tracepoint assignment causes an obvious preempt >> count leak because nothing invokes put_cpu() to undo it: >> >> softirq: huh, entered softirq 3 NET_RX with preempt_count 00000100, exited with 00000101? >> >> This clearly has seen a lot of testing in the last 3+ years... > > I'm the author who introduced the bug. FWIW, I did use it quite a bit when I > had i40e devices. Right, but always with PREEMPT_NONE and no debug option which would enforce PREEMPT_COUNT ... 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 36F823176EB for ; Mon, 9 Feb 2026 22:56:32 +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=1770677793; cv=none; b=X1+wKLNnRhofv4Pm9AcEQzJ6/oYiqpew/EYkK8klGxrBRSioejdXCCDEc7e9iDcHNLk0adMZM83GodM8Msi1PF5RqFF1FiaaI0EJ5coKV4LxmNy8oQjCvxaoeflJEdEcstr6d0LoGVhhrNY3kkRND/GBqggXmQI9t4w6MNRaDtg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770677793; c=relaxed/simple; bh=trw4gZg3u5netF1WY9Edyh3HqtUonFyD0wBYk7S4QxA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=XOZW2YlFZEJFTtnHHel1VwlrL4/S7sICuDmJGhLrVzoEYqr3IapAd/ecP3kWvax4WsP/3Ez16W135tZERtrpmqH4b/X7UsfoqX1gGOjl09EXICMFwcW7z7Hm95aROuKZWpepLqs26bc/sK4qxMn0XBTnipHJNBlKf0vMKrUaHek= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=r5kEeuHy; 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="r5kEeuHy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5A334C116C6; Mon, 9 Feb 2026 22:56:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770677792; bh=trw4gZg3u5netF1WY9Edyh3HqtUonFyD0wBYk7S4QxA=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=r5kEeuHy3lfzpJAInS+BRw3PmZL6CXsXz14Urxz8g6Z5va/QaUMHUDabPMIGZ+oYl F2tdFDYonNJcgd172JM6S7+/wpqy8viblrbx9bSbjsspn5MZUQa22gKskjS+mNZZu/ fEVmEEhQSRGh2sV5RjCGbVzSNRAeQukzkotxIEahoybo78CIOrPSwok3BFQ/wiJC70 MI/p/2hl38F+smbf6l/zw+2brV89ESzA0VtL+phuesuY+dJX/HUHtHikHIA1eCUfZq gewriuu0KzRb+bIJlXW8EJ48pn7DnAM40x70avjyMyJYDb3CnvimyA4pzCQiynhKQh rMHmHEx+jjP8A== From: Thomas Gleixner To: Joe Damato Cc: intel-wired-lan@lists.osuosl.org, Tony Nguyen , Przemek Kitszel , netdev@vger.kernel.org Subject: Re: i40e: Fix preempt count leak in napi poll tracepoint In-Reply-To: References: <87v7g8zv2o.ffs@tglx> Date: Mon, 09 Feb 2026 23:56:29 +0100 Message-ID: <87a4xhbk6a.ffs@tglx> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon, Feb 09 2026 at 14:07, Joe Damato wrote: > On Sat, Feb 07, 2026 at 11:50:23AM +0100, Thomas Gleixner wrote: >> Using get_cpu() in the tracepoint assignment causes an obvious preempt >> count leak because nothing invokes put_cpu() to undo it: >> >> softirq: huh, entered softirq 3 NET_RX with preempt_count 00000100, exited with 00000101? >> >> This clearly has seen a lot of testing in the last 3+ years... > > I'm the author who introduced the bug. FWIW, I did use it quite a bit when I > had i40e devices. Right, but always with PREEMPT_NONE and no debug option which would enforce PREEMPT_COUNT ...