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[24.6.216.183]) by smtp.gmail.com with ESMTPSA id q18sm17715537pfj.46.2021.09.27.05.52.13 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 27 Sep 2021 05:52:14 -0700 (PDT) Content-Type: text/plain; charset=us-ascii Mime-Version: 1.0 (Mac OS X Mail 14.0 \(3654.120.0.1.13\)) Subject: Re: [RFC PATCH 2/8] mm/madvise: remove unnecessary check on madvise_dontneed_free() From: Nadav Amit In-Reply-To: <20210927121902.r5gslag4nvvseoxo@box> Date: Mon, 27 Sep 2021 05:52:12 -0700 Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Peter Xu , Andrea Arcangeli , Minchan Kim , Colin Cross , Suren Baghdasarya , Mike Rapoport Content-Transfer-Encoding: quoted-printable Message-Id: <8ACD5AC6-2235-4A62-8044-F686EB26840E@gmail.com> References: <20210926161259.238054-1-namit@vmware.com> <20210926161259.238054-3-namit@vmware.com> <20210927091143.tn6ediykqycu6rtu@box.shutemov.name> <20210927121902.r5gslag4nvvseoxo@box> To: "Kirill A. Shutemov" X-Mailer: Apple Mail (2.3654.120.0.1.13) X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0B3B2801A89F X-Stat-Signature: 9yjkxea4z4uyko66brhyj6ce665qjoak Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=gmail.com header.s=20210112 header.b=lIuP9Ea+; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf06.hostedemail.com: domain of nadav.amit@gmail.com designates 209.85.216.50 as permitted sender) smtp.mailfrom=nadav.amit@gmail.com X-HE-Tag: 1632747135-499959 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000115, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Sep 27, 2021, at 5:19 AM, Kirill A. Shutemov = wrote: >=20 > On Mon, Sep 27, 2021 at 04:05:47AM -0700, Nadav Amit wrote: >> Having said that, if you want, I can turn this condition into >> WARN_ON_ONCE() or VM_BUG_ON(), although I really see no reason to >> do so. >=20 > BUILD_BUG() should be fine here. It does not work. At least my gcc is not smart enough to figure it out in build time. I can put instead: BUILD_BUG_ON(__builtin_constant_p(behavior)); for potentially smarter compilers (clang?), but I doubt it would work.