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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: stable@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