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Thu, 24 Aug 2023 19:27:11 -0700 (PDT) Received: from [10.70.252.135] ([203.208.167.146]) by smtp.gmail.com with ESMTPSA id w4-20020a637b04000000b0055fd10306a2sm335950pgc.75.2023.08.24.19.27.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 24 Aug 2023 19:27:11 -0700 (PDT) Message-ID: Date: Fri, 25 Aug 2023 10:27:00 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [PATCH v5 27/45] vmw_balloon: dynamically allocate the vmw-balloon shrinker Content-Language: en-US To: Nadav Amit Cc: Qi Zheng , Andrew Morton , "david@fromorbit.com" , "tkhai@ya.ru" , "vbabka@suse.cz" , "roman.gushchin@linux.dev" , "djwong@kernel.org" , "brauner@kernel.org" , "Paul E. McKenney" , "tytso@mit.edu" , "steven.price@arm.com" , "cel@kernel.org" , "senozhatsky@chromium.org" , "yujie.liu@intel.com" , Greg Kroah-Hartman , Muchun Song , Linux Kernel Mailing List , linux-mm , "linux-fsdevel@vger.kernel.org" , Muchun Song , Pv-drivers , Arnd Bergmann References: <20230824034304.37411-1-zhengqi.arch@bytedance.com> <20230824034304.37411-28-zhengqi.arch@bytedance.com> <2E63E088-10D8-4343-BB78-27D2ABFB95E7@vmware.com> From: Qi Zheng In-Reply-To: <2E63E088-10D8-4343-BB78-27D2ABFB95E7@vmware.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: EF16920007 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: kx3rk9argmnyn4r7cywitfd8erj1wjaj X-HE-Tag: 1692930432-320932 X-HE-Meta: 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 B7+Vw/0E 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Nadav, On 2023/8/24 23:28, Nadav Amit wrote: > > >> On Aug 23, 2023, at 8:42 PM, Qi Zheng wrote: >> >> In preparation for implementing lockless slab shrink, use new APIs to >> dynamically allocate the vmw-balloon shrinker, so that it can be freed >> asynchronously via RCU. Then it doesn't need to wait for RCU read-side >> critical section when releasing the struct vmballoon. >> >> And we can simply exit vmballoon_init() when registering the shrinker >> fails. So the shrinker_registered indication is redundant, just remove it. > > ... > > Ugh. We should have already moved to OOM notifier instead... > >> static void vmballoon_unregister_shrinker(struct vmballoon *b) >> { >> - if (b->shrinker_registered) >> - unregister_shrinker(&b->shrinker); >> - b->shrinker_registered = false; >> + shrinker_free(b->shrinker); >> } > > If the patch goes through another iteration, please add: > > b->shrinker = NULL; > > Not that this is a real issue, but I prefer it so in order to more easily > identify UAF if the function is called elsewhere. OK, will add it. > > Otherwise, LGTM. Thanks. Thanks for your review! Qi >