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[209.85.166.175]) by smtp.gmail.com with ESMTPSA id o8sm2220885ilb.64.2020.09.18.13.15.15 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 18 Sep 2020 13:15:15 -0700 (PDT) Received: by mail-il1-f175.google.com with SMTP id y9so7578133ilq.2 for ; Fri, 18 Sep 2020 13:15:15 -0700 (PDT) X-Received: by 2002:a92:2e0b:: with SMTP id v11mr32233591ile.112.1600460114870; Fri, 18 Sep 2020 13:15:14 -0700 (PDT) MIME-Version: 1.0 References: <20200917204514.GA2880159@google.com> <20200918162305.GB25599@embeddedor> <20200918193426.GA15213@embeddedor> <20200918200252.GH32101@casper.infradead.org> In-Reply-To: <20200918200252.GH32101@casper.infradead.org> From: Linus Torvalds Date: Fri, 18 Sep 2020 13:14:54 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] percpu fix for v5.9-rc6 To: Matthew Wilcox Cc: "Gustavo A. R. Silva" , Dennis Zhou , Tejun Heo , Christoph Lameter , Linux-MM , Linux Kernel Mailing List , Kees Cook 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, Sep 18, 2020 at 1:02 PM Matthew Wilcox wrote: > > I suppose it's not really necessary, we could do offsetof here, right? Yup, that would make a lot more sense. But right now, the sizeof() obviously silently works. As do a number of other fairly nonsensical things, like assigning a struct etc. And yes, I realize we may well do that too. But I think that's a dangerous pattern too, ie doing *a = *b; silently works, and copies everything but the final array. And yes - none of this is _worse_ than using zero-sized arrays, but the point is that it isn't better either. Linus