From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794621621; b=lWugCvlgjNFs3jCm2rUeTLRHr51X9A+rmK8whyxKXW3RvdVQW+95a+Gm7G9uP3Og8AD1 I+dkrCVz/WlOHWeywNaPgmD3nFhI8vW540NqGgyoM0UlPcz+/PVAsoblswVeAvzqtGP2S ZT2yA4Sd2DEn/RDpMKLb9MvkBKfsgcklYYuDOTOolAjSWeBMq2lE1nlredHxE66Kp+7ti dHkPiiXm8lDWj/m/K3UpqK6OxWMdFUpRevn3DZGUUUuTsFeSmGpS0Nxz2nZBFF/7Z3VB1 x9793YxKNWHo88T+edC+Sntlf82Wva7QsiouBAdrhNlpiYxCz7Tx6R+A3/ySXveQShA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794621621; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=xoFXsjXLKjXD/H4olKCJ+X+jvlc5wR5AHwlRcd4Ub+0=; b=PaoPOVo6polPYF/Fmz3PMMvuAQGzCoUGduE06hOZjYFUjNruWVXyCkz9kKaZ37QYzjnG a9D0Vd1Zh+lSdz6aNi2Z8fbSSG4jLnCCx4m5xzeACQlvDbrXTR98foUk3QVpGQg9WchtS LmYAWv/QdEW6X0keVv2pEn6Xk6t42a9y2RysZbnLnboSGclQX73iwBbe/tl5NMLQlVaa0 dJADlP3nPZcmf4imhv5eNIVZjKPU7nIWAwzikEMx5Es12AteHcwg4S0FjTXJPdTdmibMT z8oF5ybjqDPe5N8JoNu07RUkysr9a2sWclNJXYzUXnnrDhHeIbxNRmLGzZd6/Z85hSw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ifh8gdb+; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BEEDF606A338; Sat, 14 Nov 2026 02:00:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=ifh8gdb+ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 160661F000C4; Sat, 14 Nov 2026 02:00:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794621621; bh=xoFXsjXLKjXD/H4olKCJ+X+jvlc5wR5AHwlRcd4Ub+0=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=ifh8gdb+dPcTYXRBX0r4StppInPy9SLHfiCuCVthVRM6UGThIex/T6apM7OyMVP7n PsHBA3I1ENMUt//7BZDNSnCAS2qAjfNg0LSgBvcW2InK6bpF9lLO8bWmApiBK68FGS AiAYFPmH6iy/k6Mz1S3uRwswx0RnrMo3SiMXE6nk= Date: Fri, 13 Nov 2026 21:00:19 -0500 From: Greg KH To: dev@rebasedinc.com Cc: "stable@vger.kernel.org" , "io-uring@vger.kernel.org" , Jens Axboe , Yufan Chen Subject: Re: Subject: io_uring/eventfd: registered eventfd signals only once after the cd305ee3633a backport (6.18.y, 6.12.y, Ubuntu 26.04) Message-ID: <2026111310-pointer-citric-2f11@gregkh> References: X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Nov 13, 2026 at 11:22:38PM +0000, dev@rebasedinc.com wrote: > While working on my own async runtime on io_uring, I found what looks like a defect in the stable backports. I first saw it on Ubuntu 26.04's kernel, and I can't find any existing report of it. > > A registered io_uring eventfd stops signaling after its first deferred signal on kernels that carry the backport of cd305ee3633a ("io_uring: defer eventfd signaling when queued from a wakeup handler") but not 04fe9aeb4f3c ("io_uring/eventfd: reset deferred signal state"). > > What I see, on Ubuntu 26.04 7.0.0-1016-aws, x86_64 and arm64. Ubuntu's 7.0 kernel took the cd305ee3633a backport through the 6.18.49 stable update: Please test the real kernel.org 6.18.y release. 6.18.49 is very old. If that still has a problem, please let us know and ideally send us a backported patch. thanks, greg k-h