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 BD9AF18CBFB; Tue, 31 Dec 2024 08:27:36 +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=1735633656; cv=none; b=fbDQx8/Z/Oo/lDiP5l+rkuIZaA89DIyMablPXOjtQGA1kRCsbXEDwRxUGejWfzCrarLQ4pCn5lZnZA0SZPi1d/gIlLO6Pe6Z3G5lLWGAjdrNfbPiJaLDvaoKra06yalM6wnJ4c+64Sv8Q4TKWK3PifPXWW7pOAbyKPndY0Y1tQU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735633656; c=relaxed/simple; bh=vdaYmVIu4nzrIC3ahqNYkLwlI2zA1IocyzDKY4qLhfo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=E6eHh9TZ/QYZRIuJtMMbwQVWFvjtzqbMMWJF8GRdRJJLFye9Inw0i4By7/Ul4pRLs9j6sb5qc2cqG2mok7R61e43fGCeNIWL+9aKWUpiEnsNSBykIBW2uj/BtKhsV8HpfZS0tJVbC5PVslp/8942o70K0VxTzKhbvcm6VqQSRnQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ThiEI3QX; 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="ThiEI3QX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CEA08C4CED6; Tue, 31 Dec 2024 08:27:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1735633656; bh=vdaYmVIu4nzrIC3ahqNYkLwlI2zA1IocyzDKY4qLhfo=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ThiEI3QXEa+Ti8tLVeKyEokiIu/JQ7MIv3TUj1t6HEP/3kdlBc6sDvhAqF8Oc7xN5 j/pa9gEpn6uZkiShsapOB+vo48xy0+WIzjJ0cWjzVaj1yR6AJs6oBrgHDMDG7x9nbx CRVS6mggf3cNX0ksqVCpN7FpuUdb7gXOXZDvp6B8= Date: Tue, 31 Dec 2024 09:26:49 +0100 From: Greg KH To: Zhang Zekun Cc: dan.j.williams@intel.com, linux-kernel@vger.kernel.org, rafael.j.wysocki@intel.com, regressions@lists.linux.dev, tj@kernel.org, alex.williamson@redhat.com, chenjun102@huawei.com Subject: Re: Possible hungtask issue will be introduced with device_lock() in uevent_show() Message-ID: <2024123128-monetize-outtakes-3260@gregkh> References: <172790598832.1168608.4519484276671503678.stgit@dwillia2-xfh.jf.intel.com> <20241231075608.84009-1-zhangzekun11@huawei.com> 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: <20241231075608.84009-1-zhangzekun11@huawei.com> On Tue, Dec 31, 2024 at 03:56:08PM +0800, Zhang Zekun wrote: > Hi, Dan, Greg, > > We have found a potential tungtask issue has been introduce by commit 9a71892cbcdb ("Revert "driver core: Fix uevent_show() vs driver detach race""), which revert the rcu in device_uevent but reintroduce the device_lock() in uevent_show(). The reproduce procedure is quite simple: The revert just puts the original logic back in place, so this is not anything new that has been introduced, right? It's just that the attempted fix didn't work, so a different fix needs to happen. If you could help debug the original fix, that would be most appreciated as none of us here are arguing that there isn't a bug present, only that the fix caused different problems which required it to be reverted. thanks, greg k-h