From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 ACC6B195; Thu, 12 Dec 2024 04:49:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733978944; cv=none; b=LEjbKR09HPirqNymPuJaA3naZh2iKvZzrdYx3RmjWxhL8GKmaIG0PrRHq6CTmfMdicSI2aoY6J/wlTbH9QOIOR5cyFPLgfa7e8hykfedBZswswbrs70Y8xjG2GeZ3j/TrrZv09id3i3sh6Pc65tUALxbtle5XLcJGLzXntKxFH8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733978944; c=relaxed/simple; bh=/mGFOstPW/8O12NZTAry1P1DtwGW00o6ENEllI05cB8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=f+CyaoVP6gQwIkqoEGcrPkwkXnDFa0ucdj0dHJWMqWflJqyZErUK6G/cCNY9ripBzdF63raykgGI8a8zng0tNoy6q0Olrbyg9snp4IiU42md0ceRpYBGwq15BA0bYNctJQ3qf+TsGpuJvsoRCTpNaUFexXY7qcfcTPXGVL5OXws= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=A0XU1H+j; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="A0XU1H+j" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=UDfUCvGJZUh5a5QRBeL0Xq8pTitiUzpBZKT6xPZM7Qs=; b=A0XU1H+jpSMbY0mLRmY3PfHalf Au1ZiEEr5gGIKCN4sDxJLj6u+8norkRUWPJ4acUvudSW9qfQ5PxJdXHDo5P60NXOZEof+9tskgARD 2IafdwxtFh+4meLv0AiZCsjT5DiY4i3deelB8rkaK5lUcEocPaASsnFD++j5aA85hsiXybGsKwxin bFNyWIkKB+U8WT63DkXNbMcJN564nXvVhDkXLN9KtRNf9yVDT3rF3dzZujTFpDpiu/YPefb5zhP8d o9PK0k+Hvt07oBlO20pWWIy9EAC0evp2bqtYdB3v4p3B0GmzDC/Iwj+Obsx4Kgm+EzOQMxmyVcIXJ /YowukzA==; Received: from hch by bombadil.infradead.org with local (Exim 4.98 #2 (Red Hat Linux)) id 1tLb8G-0000000Gv0w-1FAl; Thu, 12 Dec 2024 04:49:00 +0000 Date: Wed, 11 Dec 2024 20:49:00 -0800 From: Christoph Hellwig To: Sergey Senozhatsky Cc: Theodore Ts'o , Christoph Hellwig , 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: References: <20241212035826.GH2091455@google.com> 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: <20241212035826.GH2091455@google.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Thu, Dec 12, 2024 at 12:58:26PM +0900, Sergey Senozhatsky wrote: > Hi, > > We've got two reports [1] [2] (could be the same person) which > suggest that ext4 may change page content while the page is under > write(). The particular problem here the case when ext4 is on > the zram device. zram compresses every page written to it, so if > the page content can be modified concurrently with zram's compression > then we can't really use zram with ext4. This smells like ext4 doesn't respect BDI_CAP_STABLE_WRITES somewhere.