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Fri, 7 Mar 2025 02:07:09 +0000 (GMT) Received: from epsmgms1p1new.samsung.com (unknown [182.195.42.41]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20250307020709epsmtrp1f246c0161cdecf6e660696025c4f0786~qYyf4ej2s2858928589epsmtrp1Q; Fri, 7 Mar 2025 02:07:09 +0000 (GMT) X-AuditID: b6c32a33-5a18170000005ad5-2b-67ca54cd474c Received: from epsmtip1.samsung.com ( [182.195.34.30]) by epsmgms1p1new.samsung.com (Symantec Messaging Gateway) with SMTP id 08.F1.18729.DC45AC76; Fri, 7 Mar 2025 11:07:09 +0900 (KST) Received: from ssuk04 (unknown [10.253.104.229]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250307020708epsmtip109d190634692605b936976f3bbff9bb4~qYyfpNT5c0429604296epsmtip1K; Fri, 7 Mar 2025 02:07:08 +0000 (GMT) From: "Sooyong Suk" To: "'Jaewon Kim'" , "'Christoph Hellwig'" Cc: , , , , , , , , In-Reply-To: Subject: RE: [RFC PATCH] block, fs: use FOLL_LONGTERM as gup_flags for direct IO Date: Fri, 7 Mar 2025 11:07:08 +0900 Message-ID: <848301db8f05$a1d79430$e586bc90$@samsung.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQHaiiw9LXrMK4mioaI0ilN2PEwZlQJfPoLQAkXgmoQCszXN9rMuMbSQ Content-Language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrCJsWRmVeSWpSXmKPExsWy7bCmru7ZkFPpBm/aNC3mrF/DZrH6bj+b xaH5SRanJyxisujePJPRYu8tbYvLu+awWdxb85/V4t7dBnaLyZcWsFmc/3uc1YHbY+esu+we CzaVemxeoeVx+Wypx6ZPk9g9Tsz4zeLxeZOcx6Ynb5kCOKKybTJSE1NSixRS85LzUzLz0m2V vIPjneNNzQwMdQ0tLcyVFPISc1NtlVx8AnTdMnOAjlRSKEvMKQUKBSQWFyvp29kU5ZeWpCpk 5BeX2CqlFqTkFJgV6BUn5haX5qXr5aWWWBkaGBiZAhUmZGf83/+CteCEZMXLIzINjK8luhg5 OSQETCQurZzI1MXIxSEksINR4tS9VYwQzidGiTWHj7BAON8YJR5PvM0E03Kw7ydU1V5GiYnb 7rFDOE8ZJW5/mAtWxSagLvH+zW0WEFtEIEJizf27YB3MAs8ZJd4eXswGkuAUCJRY+eE6WJGw QJBE98b5QDYHB4uAisTUuz4gYV4BS4lXnRCbeQUEJU7OfAJWziygLbFs4WtmiIsUJH4+XcYK sctNYveHD2wQNSISszvbmEH2Sggc4JCY2rICqsFFYv8UGFtY4tXxLewQtpTEy/42KLtY4lff R1aI5gZGif5jS6Aa7CVW7O9kBTmUWUBTYv0ufYhlfBLvvvaAhSUEeCU62oQgquUlfm+6wAIR FpXY9sYBwvSQuDbHfwKj4iwkj81C8tgsJA/MQli1gJFlFaNYakFxbnpqsmGBITyuk/NzNzGC k6+W8Q7Gy/P/6R1iZOJgPMQowcGsJMIruPlkuhBvSmJlVWpRfnxRaU5q8SFGU2BIT2SWEk3O B6b/vJJ4QxNLAxMzIxMLY0tjMyVx3gvbWtKFBNITS1KzU1MLUotg+pg4OKUamOwWT0i23cN6 Y5r6Lr3bDyy1/znduKtcWK6jYsI9UbTUSXG33+V7k2Yv1i964h9az6QuHSsuID29ue2XZe6B la/D5+WwSZj5TUndVV/PEet87rC4xlUNKefwtMeKMy2dPLv4Mz4YuZbGnW82nvT3x7HdR5fq 1XmlT7RV+HNT8Z3Irmcz+1gzm6L+d+cdXXI1QXbKUi9rt6kx3P9Md5ma5Un3nl4UtceESz5X 4Ajn2huP5j52tUyzDM6q2pek51Wu+2lSoeLUlfapxmbdK6NO1u0Qi1rY8I1pW+eZUyIxU8y4 emsCe3/evJby5uxL61df+TR9LGvs/tya+rXp+eY99UI//AJfT/hdaL5qqna/EktxRqKhFnNR cSIAApG8aUcEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprPIsWRmVeSWpSXmKPExsWy7bCSnO7ZkFPpBh/PsVnMWb+GzWL13X42 i0PzkyxOT1jEZNG9eSajxd5b2haXd81hs7i35j+rxb27DewWky8tYLM4//c4qwO3x85Zd9k9 Fmwq9di8Qsvj8tlSj02fJrF7nJjxm8Xj8yY5j01P3jIFcERx2aSk5mSWpRbp2yVwZXTMmstS sFWwovWVSwPjCd4uRk4OCQETiYN9Pxm7GLk4hAR2M0psP32BCSIhKvHs9zeWLkYOIFtY4vDh Yoiax4wSX6d1soPUsAmoS7x/c5sFxBYRiJDYu+05K0gRs8BHRomJzT/ZIDreM0r8vTcbrIpT IFBi5YfrYFOFBQIkGq5HgZgsAioSU+/6gFTwClhKvOq8zQRhC0qcnPkErJNZQFvi6c2ncPay ha+ZIe5UkPj5dBkrxA1uErs/fGCDqBGRmN3ZxjyBUXgWklGzkIyahWTULCQtCxhZVjFKphYU 56bnFhsWGOallusVJ+YWl+al6yXn525iBMehluYOxu2rPugdYmTiYDzEKMHBrCTCK7j5ZLoQ b0piZVVqUX58UWlOavEhRmkOFiVxXvEXvSlCAumJJanZqakFqUUwWSYOTqkGJgbfeUsbvxpN vPWOP9co5Uezwq+LVZNOfrU4VCMYoGd728s50/2b4oPeH2qfpwoqxyVnRKkdPDnj7JPlH58f zU2QbNZavEC22m3r3x3cldwGd6/zT2eoCu/R0WexCL/OXczaGdPAnJZ1cApjjH/SmpCCEsHj vT7yPVxWkQnJ2nMv8G/1FLY7yOHQuXU7z33v6NWiD7PsX0be/rKXNUj9VsC7P5NbW1d/SNv+ q3Yij6HmIYtL+QW/44UsVS+Jbs11/SIWU6HBaXx2/qlXKZ9LOJ5re7nelX7Su6DUaOG+9HOf T13YqpNpU9oqs0X1nOU1+aLKhr3lpqZf8u24zlbz7jRftDBaZM1TzZ154ZpKLMUZiYZazEXF iQDd305XMgMAAA== X-CMS-MailID: 20250307020709epcas1p4f7dbc7989988c32674ca79d7a4cf757a X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250306074101epcas1p4b24ac546f93df2c7fe3176607b20e47f References: <20250306074056.246582-1-s.suk@samsung.com> > On Fri, Mar 7, 2025 at 12:26=E2=80=AFAM=20Christoph=20Hellwig=20=0D=0A>=20wrote:=0D=0A>=20>=0D=0A>=20>=20On=20Thu,=20Mar=2006,= =202025=20at=2004:40:56PM=20+0900,=20Sooyong=20Suk=20wrote:=0D=0A>=20>=20>= =20There=20are=20GUP=20references=20to=20pages=20that=20are=20serving=20as= =20direct=20IO=0D=0A>=20buffers.=0D=0A>=20>=20>=20Those=20pages=20can=20be= =20allocated=20from=20CMA=20pageblocks=20despite=20they=20can=20be=0D=0A>= =20>=20>=20pinned=20until=20the=20DIO=20is=20completed.=0D=0A>=20>=0D=0A>= =20>=20direct=20I/O=20is=20eactly=20the=20case=20that=20is=20not=20FOLL_LON= GTERM=20and=20one=20of=20the=0D=0A>=20>=20reasons=20to=20even=20have=20the= =20flag.=20=20So=20big=20fat=20no=20to=20this.=0D=0A>=20>=0D=0A>=20=0D=0A= =0D=0AUnderstood.=0D=0A=0D=0A>=20Hello,=20thank=20you=20for=20your=20commen= t.=0D=0A>=20We,=20Sooyong=20and=20I,=20wanted=20to=20get=20some=20opinions= =20about=20this=20FOLL_LONGTERM=0D=0A>=20for=20direct=20I/O=20as=20CMA=20me= mory=20got=20pinned=20pages=20which=20had=20been=20pinned=20from=0D=0A>=20d= irect=20io.=0D=0A>=20=0D=0A>=20>=20You=20also=20completely=20failed=20to=20= address=20the=20relevant=20mailinglist=20and=0D=0A>=20>=20maintainers.=0D= =0A>=20=0D=0A>=20I=20added=20block=20maintainer=20Jens=20Axboe=20and=20the= =20block=20layer=20maillinst=20here,=0D=0A>=20and=20added=20Suren=20and=20S= andeep,=20too.=0D=0A=0D=0AThen,=20what=20do=20you=20think=20of=20using=20PF= _MEMALLOC_PIN=20for=20this=20context=20as=20below?=0D=0AThis=20will=20only= =20remove=20__GFP_MOVABLE=20from=20its=20allocation=20flag.=0D=0ASince=20__= bio_iov_iter_get_pages()=20indicates=20that=20it=20will=20pin=20user=20or= =20kernel=20pages,=0D=0Athere=20seems=20to=20be=20no=20reason=20not=20to=20= use=20this=20process=20flag.=0D=0A=0D=0Ablock/bio.c=20=7C=203=20+++=0D=0A= =201=20file=20changed,=203=20insertions(+)=0D=0A=0D=0Adiff=20--git=20a/bloc= k/bio.c=20b/block/bio.c=0D=0Aindex=2065c796ecb..671e28966=20100644=0D=0A---= =20a/block/bio.c=0D=0A+++=20b/block/bio.c=0D=0A=40=40=20-1248,6=20+1248,7= =20=40=40=20static=20int=20__bio_iov_iter_get_pages(struct=20bio=20*bio,=20= struct=20iov_iter=20*iter)=0D=0A=20=09unsigned=20len,=20i=20=3D=200;=0D=0A= =20=09size_t=20offset;=0D=0A=20=09int=20ret=20=3D=200;=0D=0A+=09unsigned=20= int=20flags;=0D=0A=20=0D=0A=20=09/*=0D=0A=20=09=20*=20Move=20page=20array= =20up=20in=20the=20allocated=20memory=20for=20the=20bio=20vecs=20as=20far= =20as=0D=0A=40=40=20-1267,9=20+1268,11=20=40=40=20static=20int=20__bio_iov_= iter_get_pages(struct=20bio=20*bio,=20struct=20iov_iter=20*iter)=0D=0A=20= =09=20*=20result=20to=20ensure=20the=20bio's=20total=20size=20is=20correct.= =20The=20remainder=20of=0D=0A=20=09=20*=20the=20iov=20data=20will=20be=20pi= cked=20up=20in=20the=20next=20bio=20iteration.=0D=0A=20=09=20*/=0D=0A+=09fl= ags=20=3D=20memalloc_pin_save();=0D=0A=20=09size=20=3D=20iov_iter_extract_p= ages(iter,=20&pages,=0D=0A=20=09=09=09=09=20=20=20=20=20=20UINT_MAX=20-=20b= io->bi_iter.bi_size,=0D=0A=20=09=09=09=09=20=20=20=20=20=20nr_pages,=20extr= action_flags,=20&offset);=0D=0A+=09memalloc_pin_restore(flags);=0D=0A=20=09= if=20(unlikely(size=20<=3D=200))=0D=0A=20=09=09return=20size=20?=20size=20:= =20-EFAULT;=0D=0A=0D=0A