From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f175.google.com (mail-pl1-f175.google.com [209.85.214.175]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6197C1A8F6D for ; Thu, 5 Dec 2024 07:05:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.175 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733382358; cv=none; b=KLK3UOCzadfwA32/y7lqctjCfazc7Y24E1IbmcFmdySjK/SSK5mkkvV2bwEGnWX/eUs7139JqiNCAb/wYXKOnPzlOSoorfmdySLZHoYdaW/9pMwD0QFlWJ46XKRooyW5iPrv2ThdZ0PfcFCVsnI0D+x7EQRDYN2byG/sYOmPwps= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733382358; c=relaxed/simple; bh=zjJgxmY2y1deqyKR6Stt9PT+fsWAX390mIy9QNV8za8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LgDMHcX4k9CD64FBoysOYrjZ84aqaCpVykbAgznwmF/xq8IJ9qKwZ/qMUzIBoQvkuqWJMNlCFT5solP7IEOjlphluwXxsvWu7jk0/Mn9HdBVwhRGRdJg/gDW6FNrhDhEZ5LwKfaMD4KO30n3MQPTpgRYuiMDBMNzGE3Jsdss9zc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org; spf=pass smtp.mailfrom=chromium.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b=YsJncUg1; arc=none smtp.client-ip=209.85.214.175 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=chromium.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=chromium.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="YsJncUg1" Received: by mail-pl1-f175.google.com with SMTP id d9443c01a7336-21577f65bdeso4965305ad.0 for ; Wed, 04 Dec 2024 23:05:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1733382357; x=1733987157; darn=vger.kernel.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=pnVjnK/k6GXXnPfVx21d5+g3wu4ThlrDFA24wTktnFw=; b=YsJncUg1a1f6U1pWsuQgbpsAxT8+oIrE0rzyWKTp8gT/FSob/b6EzyyycQe0BbTJE9 ZWlqWhSXG/rlcmo+XyLQ06rTNJlSGO1tOfNG9wAf+fg6tSHr2ZVuuQjL/hQMeGDcC7Yd U1FTktsfhLwuAtLKuR6KTRXHYbPcEB0ND0mGA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1733382357; x=1733987157; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=pnVjnK/k6GXXnPfVx21d5+g3wu4ThlrDFA24wTktnFw=; b=hPELWIhqZmU3D+bMd01mZbdHS+Y+azoZVfdG5nCnqTtIz315clvsz7erpZx3b4u24l rnKD8q6aexLq07QlY2HsFlUTsl2cLgkrOeOYqx1ZP/jOYQ2jqpGD39UZTWBk3IdUUyNv K6h3S0mx+cZsUXXa/vH2LlnasJYxGLeJNtjw2BysP08mSNTVh4UOpjg+wKANSK/wirQq 5IAPpPZrsvhlysOXu7GAnfTLU76c45ExR+WB6JfS5rcr4f7SbBvkw9a9QuUg8kb/1vX+ k/4gM5C9W5yqkJIe78+Ii45VtUeGc+XKSmOKaYBaCie0IObRUoKkPhmmV3YYxEmKpXsv FzRA== X-Forwarded-Encrypted: i=1; AJvYcCUZZ8LjCZ6ukdM9VjkIqM4XPNxK2pGKUbbKLdC47M9cIgzIt3llFy5rYrYBiBL0sU5OJjQMC/3q7efgQA==@vger.kernel.org X-Gm-Message-State: AOJu0YzattCPYCZhN0mmcyXPw2h8Snp/DTrLTr8lnPcuQHLBe+w8IHdc hXT9F6XiAG29/WCTZ25s11VZYxJMU1rqhl/Pa+0dxRRUgxZcYTTykHChYqbi5yofPtGPMERGNds = X-Gm-Gg: ASbGncvB9q/p65sUbtMkNFj2yr5DeTLd+uwCAdFjQQPRPpH+XSSfkzwSyzpLw33/FYQ wGPU1Q8bnrDGSRmTs0WJcmmohWpThSl7P0eIWx6E8xO4Fcg706z9RvXVTlwBII3GqduqGEBzT5C 5Tf2RS9jrTbWYAY+tzX5Wpbhtn59hgmWsHNDMVujJ6IWj/MtLgKQe6sPVPVLrFREEBE9Pi5OaI9 o1I4H+EKY07E2oXSSpxkgPD+kxJ09+AYh2ahfEAS7Qng/5GT1HE X-Google-Smtp-Source: AGHT+IHmb5xrPz+rTcqYtFMLlN13EqPWRM+lusJzh9gyYi0pYOG3cg9tOPzuRPSq4iV6N8E2CP/VqA== X-Received: by 2002:a17:902:dace:b0:215:65c2:f3f2 with SMTP id d9443c01a7336-215f3c56e3emr34471825ad.6.1733382356790; Wed, 04 Dec 2024 23:05:56 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:84f:5a2a:8b5d:f44f]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-215f8ef9dafsm5958855ad.120.2024.12.04.23.05.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Dec 2024 23:05:56 -0800 (PST) Date: Thu, 5 Dec 2024 16:05:52 +0900 From: Sergey Senozhatsky To: Andrew Morton , Kairui Song Cc: linux-mm@kvack.org, Minchan Kim , Sergey Senozhatsky , linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, Desheng Wu , stable@vger.kernel.org Subject: Re: [PATCH 1/2] zram: refuse to use zero sized block device as backing device Message-ID: <20241205070552.GE16709@google.com> References: <20241204180224.31069-1-ryncsn@gmail.com> <20241204180224.31069-2-ryncsn@gmail.com> Precedence: bulk X-Mailing-List: linux-block@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: <20241204180224.31069-2-ryncsn@gmail.com> On (24/12/05 02:02), Kairui Song wrote: > From: Kairui Song > > Setting a zero sized block device as backing device is pointless, and > one can easily create a recursive loop by setting the uninitialized > ZRAM device itself as its own backing device by (zram0 is uninitialized): > > echo /dev/zram0 > /sys/block/zram0/backing_dev > > It's definitely a wrong config, and the module will pin itself, > kernel should refuse doing so in the first place. > > By refusing to use zero sized device we avoided misuse cases > including this one above. > > Fixes: 013bf95a83ec ("zram: add interface to specif backing device") > Reported-by: Desheng Wu > Signed-off-by: Kairui Song > Cc: stable@vger.kernel.org Reviewed-by: Sergey Senozhatsky