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 11B752874FB; Fri, 1 May 2026 21:39:12 +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=1777671553; cv=none; b=F1i6ds3qPDTc796m1rsERflesdCCgd66vyWCjCNK5nSAow8PLf3k1uobEHFjsZusgyTvzjcsnlPRpR4p6gVah+m29jVTztJu001kyd49MoztVEU2mNdmdc+drFuHg740isiMeRz/yqnYurbOuDg5qj1q5q4iF5PsLqPftT2pbsA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777671553; c=relaxed/simple; bh=IZ4fMqegu5iKE8cxWQbd1JhDfA6xQ/yHQeOrJcQf+68=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=mm5+GgKI8wpnfapwdK2UgPe6m4DBBAZHfexFx50p49QMXwv0Tni5RRsiagP1GMAFjEJV1bDpPBIeeCCx+2HThrStK0tfgBCceo3uI68QKYYUpOxaUK+tp16Z0TwSKD4cI/MtRb3bJXkA1xAXXDkvPcC4Pc0s71oZwuVa97M88zY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=TpL0xOq1; 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="TpL0xOq1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7823AC2BCB4; Fri, 1 May 2026 21:39:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777671552; bh=IZ4fMqegu5iKE8cxWQbd1JhDfA6xQ/yHQeOrJcQf+68=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TpL0xOq1ja8r7/RpfQgHVLfSj5uIVZW+drXKO1vyEJAPdMDONTwfTBzhyop/4dQjk w2DDxccgFytfc+ASNlY4MJR3xBt7yeAM3nGeNfSeyn8nfMSk+lrMJ/+8DIDhp9uQKO P0R0E6ZcZBgOFTkDUQmyE+pcLAOV++3WAHqBogQUqtThAjTl0Vm75CCG3FZz+mUyw5 ErfkIEP9iQbtakHVl/zgKU5mGuTuWbgn4TLEN0L+skPvOC+qIDV+VRcdDkWLjA4d2d F5lYRPz9PQkvKygqqPiGC3sj0AEGdcvmR0NfozTt4QNl2eKY0ooLfjYT5HScDaxiQq BbPOp/pqFYLnA== Date: Fri, 1 May 2026 17:39:10 -0400 From: Sasha Levin To: Jens Axboe Cc: Ben Hutchings , Greg Kroah-Hartman , stable@vger.kernel.org, patches@lists.linux.dev, syzbot+641eec6b7af1f62f2b99@syzkaller.appspotmail.com, lvc-project@linuxtesting.org, Fedor Pchelkin Subject: Re: [PATCH 5.10 491/491] io_uring/poll: correctly handle io_poll_add() return value on update Message-ID: References: <20260413155819.042779211@linuxfoundation.org> <20260501111233-b371eac52cd006bfddfbd9e5-pchelkin@ispras> <20260501200000.item005-revert@kernel.org> <6eb47d20-ed49-45f6-90f1-41c15fa99896@kernel.dk> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <6eb47d20-ed49-45f6-90f1-41c15fa99896@kernel.dk> On Fri, May 01, 2026 at 03:23:33PM -0600, Jens Axboe wrote: >On 5/1/26 3:11 PM, Sasha Levin wrote: >> On Fri, 01 May 2026 11:54:18 +0300, Fedor Pchelkin wrote: >>> The Fixes: tag of upstream 84230ad2d2afb points to 97b388d70b53 >>> ("io_uring: handle completions in the core", v5.19), which is NOT >>> present in 5.10 or 5.15. Additionally, in 5.10/5.15 'preq->result' >>> is unsigned so the 'if (preq->result < 0)' check is a no-op, and >>> __io_poll_add() already completes the request when it returns >>> non-zero, leading to a potential double-completion. >>> >>> I would suggest to revert the patch from these trees because there >>> appears to be no real bug to fix. >> >> Agreed. I've reverted both the original backport and the followup >> "fix backport" commit on 5.10 and 5.15. > >Please hold off, I have fully tested these. It's quite possible they are >wonky in certain ways, but they currently fix a livelock as well that >you can hit on 5.10/15 which is arguably worse. Double claim + complete >should be handled by the poll grab side, I'm _assuming_ more cosmetic >than anything else. > >Please refrain from dropping patches until they have been confirmed by >someone that actually knows the code. I've been busy today and haven't >had time to look into this one just yet. You're just making more work >for me by dropping this you have little insight into. I haven't realized that this was a custom backport - I thought that they were pulled in without the Fixes commit being present. I'll drop the revert, luckily this wasn't pushed to stable-queue yet. -- Thanks, Sasha