From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (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 42451215048 for ; Thu, 12 Dec 2024 14:12:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.9.28.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734012753; cv=none; b=N2K7gTAVcvx0Imbk/9PJH4U3H2ulkYWHJ9lIusnHPcxIo/y+H9UEbiWpBmXpzOZ0pM7OBSXoEzp4e+p7HKFyBpRbfOzyg9Ds5pBsD8upihyYUHR0UIplqNDwTQien534xi1EKc57iprpW6jjswGW+2hOp2gawQwZ2Slqm1I/2/I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734012753; c=relaxed/simple; bh=fMIPUSjAwwy+axFu6NySo4r9+/ptfI/0mV99yxA0usE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=BK1MKpLRmzKI2OzOIjn+r7d4/4ogyN7Hr34iNosJh5qShyICHaHRJ0KMvDehTaDn158D0MOPpngXgui9Z2YsYrTCY4wyWJ/nN2f7mXI/gt5JKCW6jQIsVY7FD2Zxb0mGsT+y49ijq7ZIyd2T9iYI1LZlTAxgkqot3uEJUlYrUG0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b=OaCIR3CD; arc=none smtp.client-ip=18.9.28.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b="OaCIR3CD" Received: from cwcc.thunk.org (pool-173-48-82-226.bstnma.fios.verizon.net [173.48.82.226]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 4BCECKkE024517 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 12 Dec 2024 09:12:21 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1734012742; bh=7Jxb65opHWfpZ7IWV0B2Mylwq9EqJlQLaqwzBAA8q1Q=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=OaCIR3CDtaIGUNRmh2V0lZ4i7ZItG9YYU0YJ0n0KhAFW9mDpJRfK7tfxtMkpOYk4A mw23T99m1mseHjtUMvu4LZ5y4JrsGcZTuz/TdbAos6tEMstKcGFuOYRpGbMNwTpi4W qDC1Cy5DHLMLV4IlpT43E2f+UbhMD3A2axH7kG1SZZpfmYu4FIzlnX2ov++0+s36Lt qVnvwco1L9+b1VcQaUlM7zMz7YqV39Zv6nsJd4K2IXXw6ztbssmIBfxqwqe0qwS837 VGSRVHW9vT/cToQUzxC6Pi0u5Z/EZAm7yHQ1REm7UuZy2Erz70ymAZG6Hq6uUjmkaH fH+Sk1C+Mt8NA== Received: by cwcc.thunk.org (Postfix, from userid 15806) id 4B66515C028A; Thu, 12 Dec 2024 09:12:20 -0500 (EST) Date: Thu, 12 Dec 2024 09:12:20 -0500 From: "Theodore Ts'o" To: Christoph Hellwig Cc: Sergey Senozhatsky , Jens Axboe , caiqingfu , Andrew Morton , linux-ext4@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [bugzilla:219548] the kernel crashes when storing an EXT4 file system in a ZRAM device Message-ID: <20241212141220.GE1265540@mit.edu> References: <20241212035826.GH2091455@google.com> <20241212053739.GC1265540@mit.edu> <20241212140437.GD1265540@mit.edu> Precedence: bulk X-Mailing-List: linux-ext4@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: <20241212140437.GD1265540@mit.edu> On Thu, Dec 12, 2024 at 09:04:37AM -0500, Theodore Ts'o wrote: > For this particular use case, which is running VM's on > Chromium/ChromeOS, I suspect we do need to have some kind of solution > other than triggering a WARN_ON. Sorry, I didn't complete my thought here. We could just say, "don't use ext4 without a journal in a Chrome VM." But if the are going to allow the VM's access to external USB storage, then ext4 in no-journal mode will be the least of their problems. People trying to access USB thumbdrives or sdcards from their digital cameras using FAT file sytems will be trigerring ZBLK buffer overflow kernel crashes left, right, and center. Especially if they are on a low-cost ChromeOS device with a tiny amount of meory, such that memory pressure should be considered a foregone conclusion. :-) - Ted