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[195.135.220.15]) by mx.google.com with ESMTPS id q1si27692ejr.44.2019.04.11.11.49.23 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 11 Apr 2019 11:49:23 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id ED84FADE5; Thu, 11 Apr 2019 18:49:22 +0000 (UTC) Date: Thu, 11 Apr 2019 20:49:20 +0200 From: Michal Hocko To: Mike Kravetz Cc: Yufen Yu , linux-mm@kvack.org, kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com Subject: Re: [PATCH v2] hugetlbfs: fix protential null pointer dereference Message-ID: <20190411184920.GF10383@dhcp22.suse.cz> References: <20190411035318.32976-1-yuyufen@huawei.com> <20190411081900.GP10383@dhcp22.suse.cz> <20190411182220.GD10383@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) 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: On Thu 11-04-19 11:40:02, Mike Kravetz wrote: > On 4/11/19 11:22 AM, Michal Hocko wrote: > > On Thu 11-04-19 09:52:45, Mike Kravetz wrote: > >> Or, do you think that is too much? > >> Ideally, that comment should have been added as part of 58b6e5e8f1ad > >> ("hugetlbfs: fix memory leak for resv_map") as it could cause one to wonder > >> if resv_map could be NULL. > > > > I would much rather explain a comment explaining _when_ inode_resv_map > > might return NULL than add checks just to be sure. > > You are right. That would make more sense. It has been a while since I > looked into that code and unfortunately I did not save notes. I'll do some > research to come up with an appropriate explanation/comment. Thanks a lot! This is highly appreciated. -- Michal Hocko SUSE Labs