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AJvYcCWxqUKqltdN0k5tFbeweAkyVeRbVX295InAiyipQn2tcpLjEk3pRC1AEDkivxvt0qiPoXapNGZDXw==@kvack.org X-Gm-Message-State: AOJu0YwJk/YPVFDzN3vLhU/OYnD/Q8FrjmckIuU8AN+OifC8OLYPz/Lw 9WhXe+0MyBfcntingQZYhcYCxXTKBfAn/Px0ZkibyAnMlTAv0SVTNxgCOU6vEjx56y5srQyBaML HPDYrflx7GqIVWxCuENocFLXR0L0qO1g= X-Gm-Gg: AY/fxX42YA8InF+JPRLWJ+EUbtjmuBX6c96t38rjmRFGulV8bp8q4nnqplCwvsgdvPf PIOMFoE99tVJjEXD6BBm0mPKnRev2xpUYCO8f20pzUe4jwpo0bEFdOeCFiyURE/UvIpDjplLhD8 9l45Ltu/kpnao3FzRQ/N0WRujepImNycyHwD78dGYRwjCGOk18fXfkvq3jhEncNF/cLmlMmniIj TE5lHYuHaUw03TVMIYGsGiIpQdsVi92/8U8VWhm8O96LqzcFNuTH4b5YU6noPibW/tmOQ== X-Google-Smtp-Source: AGHT+IHK6iUXK4O2FjWbiuKko6BqfTjCmwioqFyNTMNva06WBEbn4DaE+x+NHDutsoUOQOCC9hYzmZcbMsu+Tfxl2SM= X-Received: by 2002:a05:6214:568f:b0:88c:5888:9690 with SMTP id 6a1803df08f44-88d837933aemr657165516d6.37.1767130117274; Tue, 30 Dec 2025 13:28:37 -0800 (PST) MIME-Version: 1.0 References: <20251230130110.1366374-1-wale.zhang.ftd@gmail.com> In-Reply-To: From: Barry Song <21cnbao@gmail.com> Date: Wed, 31 Dec 2025 10:28:25 +1300 X-Gm-Features: AQt7F2okIg7ROlhTPq72Ax5tD78usjQfMKe7TrJvJV-EG1QlTNuWcSQ3-NXq3_4 Message-ID: Subject: Re: [PATCH v2] mm/swapops,rmap: remove should-never-be-compiled codes. To: "David Hildenbrand (Red Hat)" Cc: Wale Zhang , akpm@linux-foundation.org, chrisl@kernel.org, ziy@nvidia.com, lorenzo.stoakes@oracle.com, matthew.brost@intel.com, linux-mm@kvack.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Queue-Id: 47F0B40004 X-Rspamd-Server: rspam04 X-Stat-Signature: ee67bysogdwhxhdqogf1ocjypjkmns4k X-HE-Tag: 1767130118-659000 X-HE-Meta: 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 KSz8wq1l FJUHT91AoPQW3LiCs7NAYG8NTC5BUWe2EychbX0wFV1NmHpajNBK7D1fPVvisiNpQn72/BxgGq+Azw492AIH16oI+wj+0AiZ0sSAlRMmPxcW6RbsFnjCxf/4ww4GW4aMid+h2nj6xfOWVyrfRx+ykFQ2KlJ8EIu2qDbKzdHmQ3KoIrY8GifY7lFf9L4f2+DMCv5msBq98QRyCzZtggIQG3lvdikXuM4VsbYEq3OUPCPps+iEjXmwRZwkNZtByX06XmYgnFDWxf9wEPh3sjwsfMBk5jLMvz1K142sjWbMWOw7TpMHbjDEq45QH4J1aiiGe1TK4uu1JQMHDnLo8s0NaOlN0P0lXOAzZeLMRkxD/zh6HAtBP4TNWthC5lj7RDXdhND81y8Ve7l9JT78k0Zvnt2jKj7VYHm7REuuhybAycNVYWg/64r8aefy0kppgPFgpn2Zw 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: List-Subscribe: List-Unsubscribe: On Wed, Dec 31, 2025 at 8:50=E2=80=AFAM David Hildenbrand (Red Hat) wrote: > > > > - break; > > +#ifdef CONFIG_NO_PAGE_MAPCOUNT > > + last =3D atomic_add_negative(-1, &folio->_entire_mapcount= ); > > + if (level =3D=3D PGTABLE_LEVEL_PMD && last) > > + nr_pmdmapped =3D folio_large_nr_pages(folio); > > + nr =3D folio_dec_return_large_mapcount(folio, vma); > > + if (!nr) { > > + /* Now completely unmapped. */ > > + nr =3D folio_large_nr_pages(folio); > > + } else { > > + partially_mapped =3D last && > > + nr < folio_large_nr_pages(folio); > > + nr =3D 0; > > The whole code was written to avoid ifdefs. The #ifdefs are only for -O0 builds, which are never a mainline requirement. However, dropping functions that contain nothing but a BUILD_BUG() seems reasonable? If those functions were actually required, the compiler would fail anyway. In that case, there doesn=E2=80=99t seem to be much value in keeping wrapper functions whose sole purpose is to contain a single BUILD_BUG(). Thanks Barry