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Mon, 22 May 2023 09:11:11 -0700 (PDT) MIME-Version: 1.0 References: <20230517150321.2890206-1-revest@chromium.org> <20230517150321.2890206-5-revest@chromium.org> <7883b08b-6bdc-a214-96a3-3f5bc1d36da4@redhat.com> In-Reply-To: <7883b08b-6bdc-a214-96a3-3f5bc1d36da4@redhat.com> From: Florent Revest Date: Mon, 22 May 2023 18:11:00 +0200 Message-ID: Subject: Re: [PATCH v2 4/5] mm: Add a NO_INHERIT flag to the PR_SET_MDWE prctl To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, catalin.marinas@arm.com, anshuman.khandual@arm.com, joey.gouly@arm.com, mhocko@suse.com, keescook@chromium.org, peterx@redhat.com, izbyshev@ispras.ru, broonie@kernel.org, szabolcs.nagy@arm.com, kpsingh@kernel.org, gthelen@google.com, toiwoton@gmail.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: CF532140009 X-Stat-Signature: junhm9xckwgjmz67n1i3749zj3ju416y X-HE-Tag: 1684771872-284902 X-HE-Meta: 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 t/QC0gyJ XuJiQ0Y60dnw3eJDgBSlM5xeEgTpI5b6H/ECt5O/etvzquZRRsu0TDqQReT3shj5DwTKG/4H3HzS20dEDeP+QRvK2EROheQvgON+R0ARZpDc696UGjo2f8VGgogaPsFF9CWLEL7PzoUFmCo9uJFLMUScNXEkq4g9TewlhjK/yqM9WCNY5B/VLx+bT/QSrhrOmWSp3198f45W+aMROkEUSxowGFibiWm0Ny4TMzgIJIXaXw1HbKTPoYzu76kW/omSr5zMePt2df1lk9ntOIWTxcNOlwbPtKM6O5kkDtMPkPeyAaxI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.002547, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, May 22, 2023 at 11:01=E2=80=AFAM David Hildenbrand wrote: > > On 17.05.23 17:03, Florent Revest wrote: > > +#define MMF_INIT_FLAGS(flags) ({ = \ > > + unsigned long new_flags =3D flags; = \ > > + if (new_flags & (1UL << MMF_HAS_MDWE_NO_INHERIT)) \ > > + new_flags &=3D ~((1UL << MMF_HAS_MDWE) | = \ > > + (1UL << MMF_HAS_MDWE_NO_INHERIT)); \ > > + new_flags & MMF_INIT_MASK; \ > > +}) > > Why the desire for macros here? :) I just thought that's what the cool kids do nowadays ?! :) Eh, I'm joking, I completely agree. Somehow this was suggested to me in v1 as a macro and I didn't think of questioning that, but a static inline function should be more readable indeed! I will fix this in v3. > We have a single user of MMF_INIT_FLAGS, why not inline or use a proper > inline function? I have a slight preference for a separate function, so we don't spill over too much of this logic in fork.c. Thanks for the review David!