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Mon, 30 May 2022 13:53:38 +0000 Received: from DS7PR12MB5744.namprd12.prod.outlook.com ([fe80::f993:a9a1:3730:a7a5]) by DS7PR12MB5744.namprd12.prod.outlook.com ([fe80::f993:a9a1:3730:a7a5%5]) with mapi id 15.20.5293.019; Mon, 30 May 2022 13:53:38 +0000 From: Zi Yan To: Anshuman Khandual Cc: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [RFC] mm/page_isolation: Fix an infinite loop in isolate_single_pageblock() Date: Mon, 30 May 2022 09:53:36 -0400 X-Mailer: MailMate (1.14r5883) Message-ID: In-Reply-To: <20220530115027.123341-1-anshuman.khandual@arm.com> References: <20220530115027.123341-1-anshuman.khandual@arm.com> Content-Type: multipart/signed; boundary="=_MailMate_428A2DF9-C7E8-4F16-8FC8-7BCA7A91934F_="; micalg=pgp-sha512; protocol="application/pgp-signature" X-ClientProxiedBy: BLAP220CA0002.NAMP220.PROD.OUTLOOK.COM (2603:10b6:208:32c::7) To DS7PR12MB5744.namprd12.prod.outlook.com (2603:10b6:8:73::18) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: f1453801-7a90-4bde-ee7a-08da4243cc16 X-MS-TrafficTypeDiagnostic: DS7PR12MB5960:EE_ X-Microsoft-Antispam-PRVS: X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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dkim=pass header.d=Nvidia.com header.s=selector2 header.b=W3XNRRFd; spf=none (imf03.hostedemail.com: domain of ziy@nvidia.com has no SPF policy when checking 40.107.237.78) smtp.mailfrom=ziy@nvidia.com; dmarc=pass (policy=reject) header.from=nvidia.com X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 0A5E72003C X-HE-Tag: 1653918805-587725 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: --=_MailMate_428A2DF9-C7E8-4F16-8FC8-7BCA7A91934F_= Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On 30 May 2022, at 7:50, Anshuman Khandual wrote: > HugeTLB allocation (32MB pages on 4K base page) via sysfs on arm64 plat= form > is getting stuck in isolate_single_pageblock(), because of an infinite = loop > Because head_pfn always evaluate the same, so does pfn, and the outer l= oop > never exits. Dropping the relevant code block, which seems redundant, m= akes > the problem go away. Thanks for the report. > > Cc: Andrew Morton > Cc: Zi Yan > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Fixes: b2c9e2fbba32 ("mm: make alloc_contig_range work at pageblock gra= nularity") > Signed-off-by: Anshuman Khandual > --- > I am not sure about this fix, and also did not find much time today to > debug any further. There are much code changes around this function in > recent days. This problem is present on latest mainline kernel. > > - Anshuman > > mm/page_isolation.c | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 6021f8444b5a..b0922fee75c1 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -389,10 +389,6 @@ static int isolate_single_pageblock(unsigned long = boundary_pfn, int flags, > struct page *head =3D compound_head(page); > unsigned long head_pfn =3D page_to_pfn(head); > > - if (head_pfn + nr_pages <=3D boundary_pfn) { > - pfn =3D head_pfn + nr_pages; > - continue; > - } > #if defined CONFIG_COMPACTION || defined CONFIG_CMA > /* > * hugetlb, lru compound (THP), and movable compound pages > -- = > 2.20.1 Can you try the patch below to see if it fixes the issue? Thanks. diff --git a/mm/page_isolation.c b/mm/page_isolation.c index 6021f8444b5a..d200d41ad0d3 100644 --- a/mm/page_isolation.c +++ b/mm/page_isolation.c @@ -385,9 +385,9 @@ static int isolate_single_pageblock(unsigned long bou= ndary_pfn, int flags, * above do the rest. If migration is not possible, just = fail. */ if (PageCompound(page)) { - unsigned long nr_pages =3D compound_nr(page); struct page *head =3D compound_head(page); unsigned long head_pfn =3D page_to_pfn(head); + unsigned long nr_pages =3D compound_nr(head); if (head_pfn + nr_pages <=3D boundary_pfn) { pfn =3D head_pfn + nr_pages; -- Best Regards, Yan, Zi --=_MailMate_428A2DF9-C7E8-4F16-8FC8-7BCA7A91934F_= Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQJDBAEBCgAtFiEEh7yFAW3gwjwQ4C9anbJR82th+ooFAmKUzGAPHHppeUBudmlk aWEuY29tAAoJEJ2yUfNrYfqKWs8P/jzfNxyO9u7L8835/kCgqvF7A+Y6zeZMnsr3 kOaYM6SoDyCZWNVQNQK/O0gvO4VQ7qeJxOhJkDNmPKc1EFsCBZmukjli2HTm0HFy /HDp0+Y6IKC6ARIMD7fhlHiXLedh3qQcdgplZ8JGMxbRAyKwLoUBUL287JbvjU+L kEwzJwLpDE+kcR1UTkhWEmEDu7zYEPkoDJqBGOiOaZFazvTaaw9ORWf6DifbEF9y R1d2SC4m0FH+9hekReAe+Z0zBNae9x06Gkjl8wfSP4Ed/IklXGBaup1xx/HyDd9p TYWsKX0iCTmQgb7039kHwHNwR7T4+3OjiSCv99Zf7smMmoneCLEmstGxKx3+T9CZ MnyAUf80tlyo7C3SPZKUq8RKuuY2Bj43EHHszOl1oi83rpL/HSyhi/PRMv1YPHq0 pTcscNFB2xay/K5Vxl14YglgV+g0wn+/mafv6DE7sV1RfqKgMY7U6H1+jckKwcNS 9ktx4B7ROixV9+ErWcTY9Vzor2Juu5nghzKYhOOq9MQR2rQZtQ2sgMWSRckiLC+T Z4rVPBiibCe73Rfx+qRpfNEkynMwSN2YiCy76jYHGE7+IsT3vTmHZ9RxpKKrAAWn tMX6DZqOaTbRzipWEnR6HSJ1E+VRL2CZMMkjGK/6rgUS5rw2JeaKY5xavwckB2Z4 GoOMZGYy =g5Ba -----END PGP SIGNATURE----- --=_MailMate_428A2DF9-C7E8-4F16-8FC8-7BCA7A91934F_=--