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 BB6F2194C63; Thu, 6 Jun 2024 10:29:26 +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=1717669767; cv=none; b=G22WSGmrAuZy3Q8CU43aFYzhTonA7Fb+07qCdeWnZt31jLs9g8aPrTP+/il/Ax9OI5EKzY9QVxoMPPWvyZslEujeCAvBbb7WTztn9lHZ2tZpfiltIfJaYP6OWQCjpxkVzV6KR6uCZK5RfEqjaQyMhpGAor1u/Mfj20Ou1fxTDu8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717669767; c=relaxed/simple; bh=qhqknNWVMeNYoWtTdBFYEjniMNaEAVGn4mAJNY/G3To=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=XHCcd+ZEpbZzSYD/fB1m/rkrI1q4YVLMWVckDGSf4mbC+USeZoX70vUeNNdx5WceKYbSzqCajDX7L8z7eK67tTVKETR6l642cYddtPmmMvV7FjXogbPK7nAVuUTF1eEv0Rrzx6K/iCWt/+hGGcpgP9TemoR6egkuJMIEQBBtmG8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=k+xivNkp; 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="k+xivNkp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 877A6C4AF0F; Thu, 6 Jun 2024 10:29:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717669766; bh=qhqknNWVMeNYoWtTdBFYEjniMNaEAVGn4mAJNY/G3To=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=k+xivNkpkyVhP1NuwNn+lsy8+20Ri42Il3zhipU1fxf8wo6vrLJp+Scs92UYJETMc yCkDwht9art5jJTfNiTyj48jjXCFnHkGKkItGnHHJQZVyLWmic+dv1hcIms34EnpPE e9aX73VH7w/YSpHPRVyk22wRauXo2Utv9OLK7svRtI9myoUyJQlJF0cXCT3T53Mn7t zWPFwtuz+tJDbwCPtb+fAkXgMsFK4D5BNENzFAgiaqQsSKXPXhbn+P8W60QYPaGImp gRYNGgW1qglssWl4XPG6ia0iOFkH3qY4FX1y0GJpTlREjlsIpQn5qxyqUzZvAo6Wbu 99yoYfX65B+Zw== Date: Thu, 6 Jun 2024 13:29:21 +0300 From: Leon Romanovsky To: Hillf Danton Cc: Tejun Heo , Peter Zijlstra , Lai Jiangshan , Zqiang , linux-kernel@vger.kernel.org, Gal Pressman , Tariq Toukan , RDMA mailing list Subject: Re: [PATCH -rc] workqueue: Reimplement UAF fix to avoid lockdep worning Message-ID: <20240606102921.GE13732@unreal> References: <4c4f1fb769a609a61010cb6d884ab2841ef716d3.1716885172.git.leon@kernel.org> <20240531034851.GF3884@unreal> <20240604105456.1668-1-hdanton@sina.com> <20240604113834.GO3884@unreal> <20240605111055.1843-1-hdanton@sina.com> <20240606073801.GA13732@unreal> Precedence: bulk X-Mailing-List: linux-kernel@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: <20240606073801.GA13732@unreal> On Thu, Jun 06, 2024 at 10:38:01AM +0300, Leon Romanovsky wrote: > On Wed, Jun 05, 2024 at 07:10:55PM +0800, Hillf Danton wrote: > > On Tue, 4 Jun 2024 21:58:04 +0300 Leon Romanovsky > > > On Tue, Jun 04, 2024 at 06:30:49AM -1000, Tejun Heo wrote: > > > > On Tue, Jun 04, 2024 at 02:38:34PM +0300, Leon Romanovsky wrote: > > > > > Thanks, it is very rare situation where call to flush/drain queue > > > > > (in our case kthread_flush_worker) in the middle of the allocation > > > > > flow can be correct. I can't remember any such case. > > > > > > > > > > So even we don't fully understand the root cause, the reimplementation > > > > > is still valid and improves existing code. > > > > > > > > It's not valid. pwq release is async and while wq free in the error path > > > > isn't. The flush is there so that we finish the async part before > > > > synchronize error handling. The patch you posted will can lead to double > > > > free after a pwq allocation failure. We can make the error path synchronous > > > > but the pwq free path should be updated first so that it stays synchronous > > > > in the error path. Note that it *needs* to be asynchronous in non-error > > > > paths, so it's going to be a bit subtle one way or the other. > > > > > > But at that point, we didn't add newly created WQ to any list which will execute > > > that asynchronous release. Did I miss something? > > > > > Maybe it is more subtle than thought, but not difficult to make the wq > > allocation path sync. See if the patch could survive your test. > > Thanks, I started to run our tests with Dan's revert. > https://lore.kernel.org/all/171711745834.1628941.5259278474013108507.stgit@dwillia2-xfh.jf.intel.com/ > > As premature results, it fixed my lockdep warnings, but it will take time till I get full confidence. Don't series fixed reported issue. Thanks