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[209.85.167.50]) by smtp.gmail.com with ESMTPSA id r23sm2267250lfi.33.2020.04.10.17.19.31 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Apr 2020 17:19:31 -0700 (PDT) Received: by mail-lf1-f50.google.com with SMTP id x23so2470845lfq.1 for ; Fri, 10 Apr 2020 17:19:31 -0700 (PDT) X-Received: by 2002:ac2:4466:: with SMTP id y6mr3957211lfl.125.1586564371332; Fri, 10 Apr 2020 17:19:31 -0700 (PDT) MIME-Version: 1.0 References: <20200410143047.bf34a933ce1affdc042c7c80@linux-foundation.org> <20200410213235.M6eTaELL2%akpm@linux-foundation.org> <20200410235358.GA38470@xz-x1> In-Reply-To: <20200410235358.GA38470@xz-x1> From: Linus Torvalds Date: Fri, 10 Apr 2020 17:19:15 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [patch 07/35] mm/gup: fix null pointer dereference detected by coverity To: Peter Xu Cc: Andrew Morton , ira.weiny@intel.com, Linux-MM , miles.chen@mediatek.com, mm-commits@vger.kernel.org Content-Type: text/plain; charset="UTF-8" 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 Fri, Apr 10, 2020 at 4:54 PM Peter Xu wrote: > > Though I'm not sure how to teach Coverity about the fact. Maybe a > "BUG_ON(unlocked == NULL)" (which contains an unreachable() inside) > before referencing unlocked? Please don't add BUG_ON's. In the "that would be a horrible bug" case, I'd rather see a NULL pointer cause a fault, than see a BUG_ON. Linus