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Fri, 08 Nov 2024 19:42:50 -0800 (PST) Received: from google.com ([2401:fa00:8f:203:eeab:613e:a460:41fd]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-724078bfccfsm4666547b3a.82.2024.11.08.19.42.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 08 Nov 2024 19:42:50 -0800 (PST) Date: Sat, 9 Nov 2024 12:42:46 +0900 From: Sergey Senozhatsky To: Liu Shixin Cc: Sergey Senozhatsky , Andrew Morton , Minchan Kim , Jens Axboe , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [PATCH] zram: fix NULL pointer in comp_algorithm_show() Message-ID: <20241109034246.GB549125@google.com> References: <20241108100147.3776123-1-liushixin2@huawei.com> <20241109011249.GA549125@google.com> 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=us-ascii Content-Disposition: inline In-Reply-To: On (24/11/09 11:23), Liu Shixin wrote: > >> Fixes: 7ac07a26dea7 ("zram: preparation for multi-zcomp support") > > So I think this fixes something much older, probably around e46b8a030d76d > > time (2014). > > The NULL pointer is introduced when zram->compressor is changed to zram->comp_algs in > 7ac07a26dea, where the former is an array of chars and the latter is an array of pointers. > Before that, if we cat comp_algorithm int the time window, we will get a message with no > algorithm selected like this: Good point, you are right.