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[79.139.184.182]) by smtp.googlemail.com with ESMTPSA id d23sm3102281ljl.115.2021.07.22.06.46.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 22 Jul 2021 06:46:00 -0700 (PDT) Subject: Re: [PATCH v14 062/138] mm/migrate: Add folio_migrate_copy() To: Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, "Theodore Y. Ts'o" References: <20210715033704.692967-1-willy@infradead.org> <20210715033704.692967-63-willy@infradead.org> From: Dmitry Osipenko Message-ID: Date: Thu, 22 Jul 2021 16:45:59 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: B5ED8B000193 X-Stat-Signature: kef8ikpy9r6ccycxchr6ysf46jdy8x9n Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=ODQJCwhH; spf=pass (imf25.hostedemail.com: domain of digetx@gmail.com designates 209.85.167.50 as permitted sender) smtp.mailfrom=digetx@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-HE-Tag: 1626961562-641462 Content-Transfer-Encoding: quoted-printable 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: 22.07.2021 15:29, Matthew Wilcox =D0=BF=D0=B8=D1=88=D0=B5=D1=82: > On Thu, Jul 22, 2021 at 02:52:28PM +0300, Dmitry Osipenko wrote: ... > The obvious solution is just to change folio_copy(): >=20 > { > - unsigned i, nr =3D folio_nr_pages(src); > + unsigned i =3D 0; > + unsigned nr =3D folio_nr_pages(src); >=20 > - for (i =3D 0; i < nr; i++) { > - cond_resched(); > + for (;;) { > copy_highpage(folio_page(dst, i), folio_page(src, i)); > + if (i++ =3D=3D nr) This works with the ++i precedence change. Thanks! > + break; > + cond_resched(); > } > } >=20 > now it only calls cond_resched() for multi-page folios. ... Thank you for the explanation and for the fix! The fs/ and mm/ are mostly outside of my scope, hope you'll figure out the buffer-head case soon.