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 226A62D9EC2 for ; Tue, 21 Apr 2026 13:55:40 +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=1776779741; cv=none; b=S6vSXLr9nsxg9mbR51Q0pVqniPrCdXd5O5HYMz5M01eL0rC3LYv8NoTnSsaqiEAzRLHmwB+OqW9w5fJ7xg1+wCd5tRl/LyLoDm7POV2ta22v6GkYWkrZQk97d8HTb/CorLLkyEs2eLrmTQNGX9SxNIpZEhe+iOK3wrXzzSYVJbQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776779741; c=relaxed/simple; bh=Pn79hZC55AAJm6orMAw/AtvVsrxQLBNVHTd3te5BSTo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bxkkO32YNRJo9pZgBovDj2JxK0HjWaqkz5a6Ibg3e/lkEkqqivtvw9XcLzFuayHhh6YlHPfX9UDow0PNCDSkG3z7nQnLEbrDYdEVJutAYf3SxQ77mxLR+9Ix4Xh0rovt6J/csoZdd4WFq9PXK+hbTjR4t+OFA4S+m+bD9YX90a0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vmUN33M5; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="vmUN33M5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CF39C2BCB0; Tue, 21 Apr 2026 13:55:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1776779740; bh=Pn79hZC55AAJm6orMAw/AtvVsrxQLBNVHTd3te5BSTo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=vmUN33M5R/+URLDZgEhEcZyTKMvTLlvvc8muScgz0dpDA9LqoP4tJEVtAJfymcujP uChhYxduKmXlWBEPLQwfsc79VjP1x5B4Y7Po6zwUmPbw/tGfjqbbRGCKAMeUSTxbTP nJNd8eyfqOmhcPT2aIk2NUThsMmZLojt81SPLd+o= Date: Tue, 21 Apr 2026 15:55:38 +0200 From: Greg Kroah-Hartman To: Jens Axboe Cc: io-uring@vger.kernel.org Subject: Re: [PATCH] io_uring: take page references for NOMMU pbuf_ring mmaps Message-ID: <2026042108-fiscally-unglazed-56c7@gregkh> References: <2026042115-body-attention-d15b@gregkh> <842a9dff-b12c-4cec-bc8d-8c1adb3ba280@kernel.dk> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <842a9dff-b12c-4cec-bc8d-8c1adb3ba280@kernel.dk> On Tue, Apr 21, 2026 at 07:50:32AM -0600, Jens Axboe wrote: > On 4/21/26 7:46 AM, Greg Kroah-Hartman wrote: > > Note, I have no way of testing this, I'm only forwarding this on because > > I got the bug report and was able to generate something that "seems" > > AI bug report I presume? Because I can't imagine anyone ever attempted > to run this. Yes, I got a bunch of "non-mmu" bug reports, which is a bit odd but I guess you can do that with qemu these days? I should dig into that, maybe that way I can test this and get a reproducer for you. If not, let's just bin the thing. > > correct, but it might be a total load of crap here, my knowledge of the > > vm layer is very low so take this for where it is coming from (i.e. a > > non-deterministic pattern matching system.) > > > > I do have another patch that just disables io_uring for !MMU systems, if > > you want that instead? Or is this feature something that !MMU devices > > actually care about? > > I mean, who really cares about !MMU in the first place, we should just > kill that off with a passion. > > Let me take a closer look at this and bounce it past some vm people, my > nommu knowledge is close to zero as it's never been relevant in my > professional life time. Which is saying something... Let me try to get a reproducer going first, let's not waste any more human time on this just yet, sorry for sending this out without that done first... thanks, greg k-h