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 503182032D; Fri, 5 Apr 2024 11:19:34 +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=1712315975; cv=none; b=E8JaE1uVvkFWsxq04bn/M378FfwiLZIBvBRsHVJi6fgAWOuagX1d2rWG/HoezS1r0OKraT0QfWfP117/KLU2s9+SYdH4eIW47OIOsZfzC/bjFYm15OpCS/hdeteZX3CN6sGRX31WF2U94T5cLLzqYmVr129yJ0jZOr0StInjZk8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712315975; c=relaxed/simple; bh=D6eENCgBQXPyEg6sNqruhx+GuX+x1pb2tuOAUmIs064=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=duVJ/uVfU/XoeAPNZiwUPckIkZqFqb/pT+Aq3YncPrmBS8scwuCZRl1JnMaM312WZn1/s562qKRHEezlHd01F7V89qF30yU7PhnuJOaDXyJfoYSBPuDiI6fdF6AvFsLif7s00dgobBKyOIUBtn4bomYkKon3oApT3ECowgytI0M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Wl5ElMuB; 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="Wl5ElMuB" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EBE1BC433C7; Fri, 5 Apr 2024 11:19:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1712315974; bh=D6eENCgBQXPyEg6sNqruhx+GuX+x1pb2tuOAUmIs064=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Wl5ElMuBHn+2iLXVfIq4ibHiXCmslFxi2+3OaN21w77qfuymMyGLzQZDdLhxyd95k B55y7c6Z5FvTlUgHyRkglYEG+G1LfCOTznmo6vgkCB/T5XLMjItKlj8NdFL95E2cm4 bjattl7wZZKdArnOTwFMZWg6+0AMyXNCzvTXl/Cu1O5TKRZDvo1AUhjlN/SEofoPH/ r4CFQnJJRca/6X9Oh+Hz12TE5hT+wacwfcpX55W6HhKAPUyqEttdwz03FLjLpFZwAy QAlDIZhfoqbINe7+jhufW6UR6vvrF1F/JDOhCavqfMA8BFIIidI20X38jKxFjrKbns 08NX9ff4uJLUA== Date: Fri, 5 Apr 2024 13:19:27 +0200 From: Christian Brauner To: Christoph Hellwig Cc: Amir Goldstein , Al Viro , syzbot , gregkh@linuxfoundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tj@kernel.org, valesini@yandex-team.ru, Jan Kara , Miklos Szeredi Subject: Re: [syzbot] [kernfs?] possible deadlock in kernfs_fop_llseek Message-ID: <20240405-ozonwerte-hungrig-326d97c62e65@brauner> References: <00000000000098f75506153551a1@google.com> <0000000000002f2066061539e54b@google.com> <20240404081122.GQ538574@ZenIV> <20240404082110.GR538574@ZenIV> <20240405065135.GA3959@lst.de> 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=utf-8 Content-Disposition: inline In-Reply-To: <20240405065135.GA3959@lst.de> On Fri, Apr 05, 2024 at 08:51:35AM +0200, Christoph Hellwig wrote: > On Thu, Apr 04, 2024 at 12:33:40PM +0300, Amir Goldstein wrote: > > I don't follow what you are saying. > > Which code is in non-starter violation? > > kernfs for calling lookup_bdev() with internal of->mutex held? > > That is a huge problem, and has been causing endless annoying lockdep > chains in the block layer for us. If we have some way to kill this > the whole block layer would benefit. Why not just try and add a better resume api that forces resume to not use a path argument neither for resume_file nor for writes to /sys/power/resume. IOW, extend the protocol what can get written to /sys/power/resume and then phase out the path argument. It'll take a while but it's a possibly clean solution.