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Fri, 01 Sep 2023 03:29:18 -0700 (PDT) MIME-Version: 1.0 References: <20230831105252.1385911-1-zhaoyang.huang@unisoc.com> In-Reply-To: From: Zhaoyang Huang Date: Fri, 1 Sep 2023 18:29:07 +0800 Message-ID: Subject: Re: [PATCH] mm: make __GFP_SKIP_ZERO visible to skip zero operation To: Matthew Wilcox , glider@google.com Cc: "zhaoyang.huang" , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, ke.wang@unisoc.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: CE62280008 X-Rspam-User: X-Stat-Signature: nh6u7f3pe8ry7rwmzcjsfaje3t1o4t88 X-Rspamd-Server: rspam03 X-HE-Tag: 1693564160-947203 X-HE-Meta: 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 NUb5r+lR 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 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: loop alex On Thu, Aug 31, 2023 at 8:16=E2=80=AFPM Matthew Wilcox wrote: > > On Thu, Aug 31, 2023 at 06:52:52PM +0800, zhaoyang.huang wrote: > > From: Zhaoyang Huang > > > > There is no explicit gfp flags to let the allocation skip zero > > operation when CONFIG_INIT_ON_ALLOC_DEFAULT_ON=3Dy. I would like to mak= e > > __GFP_SKIP_ZERO be visible even if kasan is not configured. > > This bypasses a security feature so you're going to have to do a little > better than "I want it". Thanks for pointing this out. What I want to do is to give the user a way to exempt some types of pages from being zeroed, which could help on performance issues. Could we have the most safety concern admin use INIT_ON_FREE while the less concerned use INIT_ON_ALLOC & __GFP_SKIP_ZERO as a light version method? > > > Signed-off-by: Zhaoyang Huang > > --- > > include/linux/gfp_types.h | 3 +-- > > 1 file changed, 1 insertion(+), 2 deletions(-) > > mode change 100644 =3D> 100755 include/linux/gfp_types.h > > What is this garbage? Header files should not be executable. sorry for that, will remove