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t=1684508948; bh=rDLgLUJ0rrmB/7UJshPY5Np0IALAi+sq2a59vSquYrM=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=XwtGzrlehOHApxGNhTJs7uj3zzus/T/qulGrC436Io2KRBxHmBrifjbaz4joKgfVa t9Kj0/dQiDzIlb1sQKd9sQ4ac/gNMK96DS78eVtxKVUwdZBY0lQz8rCTqDNx1ljLCn bFD1c0xwaQc+oOE+hNCC/NQFoQv7alZRj1MZnN3PB7dGKjy6Tt4CoQZpovflYHFYkX 45zZZPMyn/s88NmUsluCQPyO7sVqVB4jC9LMVXIpl3ExRhepi8Ckx9qWStHFoE+N60 PddB1nTcBq+ECU5Sdp456AJMpfRJx79qKNxqWDc0Hd127uKHIGAyFyfiO+XUQPQn/r mb2+JnUgaT+Cw== Received: by mail-lj1-f175.google.com with SMTP id 38308e7fff4ca-2af2958db45so3476541fa.1 for ; Fri, 19 May 2023 08:09:08 -0700 (PDT) X-Gm-Message-State: AC+VfDy6XtDnVE9eY0HdJJ2EgR1gtWQoP50EvvCL/sYfbYBnFMyKyn4Q a0P+PhRCSXmu78O4Joc8I1naJ919u2C4YxKWg8Y= X-Google-Smtp-Source: ACHHUZ5ITafro9iwmTU6vR/smLxeVBItH3Onrt90yV7r9RdUM8xsIZj5uBIiwP+QRe9z/Lw0esi3rIVYclGXiVS2V20= X-Received: by 2002:a2e:8845:0:b0:2af:228a:a277 with SMTP id z5-20020a2e8845000000b002af228aa277mr1174433ljj.21.1684508946420; Fri, 19 May 2023 08:09:06 -0700 (PDT) MIME-Version: 1.0 References: <20230518152354.GD4967@kernel.org> In-Reply-To: From: Song Liu Date: Fri, 19 May 2023 08:08:54 -0700 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [RFC PATCH 1/5] mm: intorduce __GFP_UNMAPPED and unmapped_alloc() To: Kent Overstreet Cc: Mike Rapoport , linux-mm@kvack.org, Andrew Morton , Dave Hansen , Peter Zijlstra , Rick Edgecombe , Thomas Gleixner , Vlastimil Babka , linux-kernel@vger.kernel.org, x86@kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: AF2301401F4 X-Stat-Signature: kohpr8duq8uoo67x1wynf4sscf1pctai X-Rspam-User: X-HE-Tag: 1684508950-318205 X-HE-Meta: U2FsdGVkX1+sxtNmbt18hlCoog6R+KAzojiM6tUhLRvfoX8hK9olqKYADAkM6tuas74Wi/CuQLWe2wOCbzZkFxVE9Ju1Ms7K92q+KFB7A0Ar0qnz1/dJ+vpFLpUN8cfipfQgnEYwdXnhcSnpVzfvX8PC93J0KQLhmpNbXP0yaopGSYYI1ygDkt2SH6H6pVrVVHH8x5Vw3PHp9oAqBcpH0TPWMkORJEQRLa1rQTZadwWQSHeOT9X7YadAM+9btzJP3q0rK2D89gzfe1/ke6VjtKiob/K7N5Xec8LGwdfg7qunk071bqQjlEZckG61FinnJFyLpOID4WVSLucD2mjnYqKhcJcS3kRYkq9xg9C9srOetVnRuN2o/sXYuI2ivmglPXx++ulgw77PtRs4nxJj6OXt/1uLm7Ll56esOvXojTO2tNf/pOVsmzj1iUWlv+/VO1rKRTfHpXQPudwcTXIqlxmew+gktOizD88IZPWefTmb7IslwkPdPWWr5IcOoIF7fW3/lm/D9ybeCmb+a0ggz47mVql2w+kMShbUTGVzAtQ/b4ABJ4t9jrn5/FqzY1rRVD7b41orcN7W/HxWN8kKJCupBfaLSKgiCTiGkvgFJrmvXh6FJK0YzmaNlaX3yB38WAhkPkdeUNZxR5j9068jo+YYH27Yrqn4c9riX35k1OvyXWuMCkbO1L/NFuLx3mXxXvoCWvHl5T5zH/KdfwD1VYpRVM8DKSrP33V8EjTwd3YMsKRbW0KU+IX+oQPsQPf1HXDbDDKBygwPeStRgjitlaFaonMOxm1lWV1Pp6cKTHiDpzEmnuXZPSxQ3RUJ+ifcwDnXnv4+rOM4WZFT1VxV9+nsEf3dSJVhrC+vGVZQ4seK0LVWk9IY3jK+yYBwnoF85Yc/RLPYV2F64ZZ6Yqo+RwfXyNRFrzbpT/cn1+3HwlydoRES7FH+5PKNH5z/Q/0TxWdzIEkEcuX5MdB12Nl 1QAAKVj0 EXbC6Fp0EN9MCsjql5PHNjWyrvzqWZGU+JiijDeTNRRehb2X4y6UB3okbk2Nu/jBv0SyBBRoeIvK3oU9agWBUApCc2zuiXIIZePaeWrbDp4uivXs/cE2q9ELWjRsaZX23xeqAgYpVGNMfirlY3gegJ2+wZ/jCaKXn0Yt+2rzLufufBG0apquP7fXUdbHXz6D9iiN13tR1dJygusOrMYLIJobb4VY9uH80gp/4c4wI/YFcBqVOrQt8uGEuqw+D725IjLeP2hn1xpk99k/tAT1BzwngXF7r9bgf6zh8Uu223pv4D+ETPGdlPJzE/2GmUkVBQXG9IaID48G8ZYZR4cGp8OoILybim+KrhW8aUpxhD8TTT2o= 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 Thu, May 18, 2023 at 6:24=E2=80=AFPM Kent Overstreet wrote: > > On Thu, May 18, 2023 at 01:51:08PM -0700, Song Liu wrote: > > > To allocate memory for text, we will allocate 2MiB, make it ROX, and th= en > > use it for many small allocations. IIUC, buddy allocator will use unall= ocated > > parts of this page for metadata. I guess this may be a problem, as the > > whole page is ROX now, and we have to use text_poke to write to it. > > The standard kernel buddy allocator does _not_ store anything in the > page itself - because the page might be a highmem page. Thanks for the correction. Song > > That's also why I went with the bitmap for my slab allocator; standard > kernel slab allocator stores a freelist ptr in free objects.