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Wed, 15 Apr 2020 11:47:00 +0000 (UTC) Received: from [10.10.113.210] (ovpn-113-210.rdu2.redhat.com [10.10.113.210]) by smtp.corp.redhat.com (Postfix) with ESMTPS id B64B660BE2; Wed, 15 Apr 2020 11:46:58 +0000 (UTC) Subject: Re: [PATCH] mm/hugetlb: avoid weird message in hugetlb_init To: Mike Kravetz , "Longpeng (Mike)" Cc: arei.gonglei@huawei.com, huangzhichao@huawei.com, Matthew Wilcox , Andrew Morton , Qian Cai , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20200305033014.1152-1-longpeng2@huawei.com> <43017337-fe28-16e0-fbdd-d6368bdd2eb2@oracle.com> <641eae15-1ea7-c573-0d64-09dcccc1717d@redhat.com> <0b8d283f-dd31-b980-5d53-4bbca4014da7@oracle.com> From: Nitesh Narayan Lal Autocrypt: addr=nitesh@redhat.com; prefer-encrypt=mutual; keydata= mQINBFl4pQoBEADT/nXR2JOfsCjDgYmE2qonSGjkM1g8S6p9UWD+bf7YEAYYYzZsLtbilFTe z4nL4AV6VJmC7dBIlTi3Mj2eymD/2dkKP6UXlliWkq67feVg1KG+4UIp89lFW7v5Y8Muw3Fm uQbFvxyhN8n3tmhRe+ScWsndSBDxYOZgkbCSIfNPdZrHcnOLfA7xMJZeRCjqUpwhIjxQdFA7 n0s0KZ2cHIsemtBM8b2WXSQG9CjqAJHVkDhrBWKThDRF7k80oiJdEQlTEiVhaEDURXq+2XmG jpCnvRQDb28EJSsQlNEAzwzHMeplddfB0vCg9fRk/kOBMDBtGsTvNT9OYUZD+7jaf0gvBvBB lbKmmMMX7uJB+ejY7bnw6ePNrVPErWyfHzR5WYrIFUtgoR3LigKnw5apzc7UIV9G8uiIcZEn C+QJCK43jgnkPcSmwVPztcrkbC84g1K5v2Dxh9amXKLBA1/i+CAY8JWMTepsFohIFMXNLj+B RJoOcR4HGYXZ6CAJa3Glu3mCmYqHTOKwezJTAvmsCLd3W7WxOGF8BbBjVaPjcZfavOvkin0u DaFvhAmrzN6lL0msY17JCZo046z8oAqkyvEflFbC0S1R/POzehKrzQ1RFRD3/YzzlhmIowkM BpTqNBeHEzQAlIhQuyu1ugmQtfsYYq6FPmWMRfFPes/4JUU/PQARAQABtCVOaXRlc2ggTmFy YXlhbiBMYWwgPG5pbGFsQHJlZGhhdC5jb20+iQI9BBMBCAAnBQJZeKUKAhsjBQkJZgGABQsJ CAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEKOGQNwGMqM56lEP/A2KMs/pu0URcVk/kqVwcBhU SnvB8DP3lDWDnmVrAkFEOnPX7GTbactQ41wF/xwjwmEmTzLrMRZpkqz2y9mV0hWHjqoXbOCS 6RwK3ri5e2ThIPoGxFLt6TrMHgCRwm8YuOSJ97o+uohCTN8pmQ86KMUrDNwMqRkeTRW9wWIQ EdDqW44VwelnyPwcmWHBNNb1Kd8j3xKlHtnS45vc6WuoKxYRBTQOwI/5uFpDZtZ1a5kq9Ak/ MOPDDZpd84rqd+IvgMw5z4a5QlkvOTpScD21G3gjmtTEtyfahltyDK/5i8IaQC3YiXJCrqxE r7/4JMZeOYiKpE9iZMtS90t4wBgbVTqAGH1nE/ifZVAUcCtycD0f3egX9CHe45Ad4fsF3edQ ESa5tZAogiA4Hc/yQpnnf43a3aQ67XPOJXxS0Qptzu4vfF9h7kTKYWSrVesOU3QKYbjEAf95 NewF9FhAlYqYrwIwnuAZ8TdXVDYt7Z3z506//sf6zoRwYIDA8RDqFGRuPMXUsoUnf/KKPrtR ceLcSUP/JCNiYbf1/QtW8S6Ca/4qJFXQHp0knqJPGmwuFHsarSdpvZQ9qpxD3FnuPyo64S2N Dfq8TAeifNp2pAmPY2PAHQ3nOmKgMG8Gn5QiORvMUGzSz8Lo31LW58NdBKbh6bci5+t/HE0H pnyVf5xhNC/FuQINBFl4pQoBEACr+MgxWHUP76oNNYjRiNDhaIVtnPRqxiZ9v4H5FPxJy9UD Bqr54rifr1E+K+yYNPt/Po43vVL2cAyfyI/LVLlhiY4yH6T1n+Di/hSkkviCaf13gczuvgz4 KVYLwojU8+naJUsiCJw01MjO3pg9GQ+47HgsnRjCdNmmHiUQqksMIfd8k3reO9SUNlEmDDNB XuSzkHjE5y/R/6p8uXaVpiKPfHoULjNRWaFc3d2JGmxJpBdpYnajoz61m7XJlgwl/B5Ql/6B dHGaX3VHxOZsfRfugwYF9CkrPbyO5PK7yJ5vaiWre7aQ9bmCtXAomvF1q3/qRwZp77k6i9R3 tWfXjZDOQokw0u6d6DYJ0Vkfcwheg2i/Mf/epQl7Pf846G3PgSnyVK6cRwerBl5a68w7xqVU 4KgAh0DePjtDcbcXsKRT9D63cfyfrNE+ea4i0SVik6+N4nAj1HbzWHTk2KIxTsJXypibOKFX 2VykltxutR1sUfZBYMkfU4PogE7NjVEU7KtuCOSAkYzIWrZNEQrxYkxHLJsWruhSYNRsqVBy KvY6JAsq/i5yhVd5JKKU8wIOgSwC9P6mXYRgwPyfg15GZpnw+Fpey4bCDkT5fMOaCcS+vSU1 UaFmC4Ogzpe2BW2DOaPU5Ik99zUFNn6cRmOOXArrryjFlLT5oSOe4IposgWzdwARAQABiQIl BBgBCAAPBQJZeKUKAhsMBQkJZgGAAAoJEKOGQNwGMqM5ELoP/jj9d9gF1Al4+9bngUlYohYu 0sxyZo9IZ7Yb7cHuJzOMqfgoP4tydP4QCuyd9Q2OHHL5AL4VFNb8SvqAxxYSPuDJTI3JZwI7 d8JTPKwpulMSUaJE8ZH9n8A/+sdC3CAD4QafVBcCcbFe1jifHmQRdDrvHV9Es14QVAOTZhnJ vweENyHEIxkpLsyUUDuVypIo6y/Cws+EBCWt27BJi9GH/EOTB0wb+2ghCs/i3h8a+bi+bS7L FCCm/AxIqxRurh2UySn0P/2+2eZvneJ1/uTgfxnjeSlwQJ1BWzMAdAHQO1/lnbyZgEZEtUZJ x9d9ASekTtJjBMKJXAw7GbB2dAA/QmbA+Q+Xuamzm/1imigz6L6sOt2n/X/SSc33w8RJUyor SvAIoG/zU2Y76pKTgbpQqMDmkmNYFMLcAukpvC4ki3Sf086TdMgkjqtnpTkEElMSFJC8npXv 3QnGGOIfFug/qs8z03DLPBz9VYS26jiiN7QIJVpeeEdN/LKnaz5LO+h5kNAyj44qdF2T2AiF HxnZnxO5JNP5uISQH3FjxxGxJkdJ8jKzZV7aT37sC+Rp0o3KNc+GXTR+GSVq87Xfuhx0LRST NK9ZhT0+qkiN7npFLtNtbzwqaqceq3XhafmCiw8xrtzCnlB/C4SiBr/93Ip4kihXJ0EuHSLn VujM7c/b4pps Organization: Red Hat Inc, Message-ID: <5c6595f7-7a8a-935f-7267-c2a16ccb1997@redhat.com> Date: Wed, 15 Apr 2020 07:46:56 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <0b8d283f-dd31-b980-5d53-4bbca4014da7@oracle.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0dG372tR7vYXwb95lp3IL4xTLq1ddr9Ct" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --0dG372tR7vYXwb95lp3IL4xTLq1ddr9Ct Content-Type: multipart/mixed; boundary="IPsz3W7J0spvKcK1NCcJaLgHJcbQVPqQS" --IPsz3W7J0spvKcK1NCcJaLgHJcbQVPqQS Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US On 4/15/20 12:03 AM, Mike Kravetz wrote: > On 4/13/20 2:21 PM, Nitesh Narayan Lal wrote: >> On 4/13/20 2:33 PM, Mike Kravetz wrote: >>> On 4/10/20 8:47 AM, Nitesh Narayan Lal wrote: >>>> Hi Mike, >>>> >>>> On platforms that support multiple huge page sizes when 'hugepagesz' i= s not >>>> specified before 'hugepages=3D', hugepages are not allocated. (For exa= mple >>>> if we are requesting 1GB hugepages) >>> Hi Nitesh, >>> >>> This should only be an issue with gigantic huge pages. This is because >>> hugepages=3DX not following a hugepagesz=3DY specifies the number of hu= ge pages >>> of default size to allocate. It does not currently work for gigantic p= ages. >> I see, since we changed the default hugepages to gigantic pages and we m= issed >> 'hugepagesz=3D' no page were allocated of any type. >> >>> In the other thread, I provided this explanation as to why: >>> It comes about because we do not definitively set the default huge page= size >>> until after command line processing (in hugetlb_init). And, we must >>> preallocate gigantic huge pages during command line processing because = that >>> is when the bootmem allocater is available. >>> >>> I will be looking into modifying this behavior to allocate the pages as >>> expected, even for gigantic pages. >> Nice, looking forward to it. >> >>>> In terms of reporting meminfo and /sys/kernel/../nr_hugepages reports = the >>>> expected results but if we use sysctl vm.nr_hugepages then it reports = a non-zero >>>> value as it reads the max_huge_pages from the default hstate instead o= f >>>> nr_huge_pages. >>>> AFAIK nr_huge_pages is the one that indicates the number of huge pages= that are >>>> successfully allocated. >>>> >>>> Does vm.nr_hugepages is expected to report the maximum number of hugep= ages? If >>>> so, will it not make sense to rename the procname? >>>> >>>> However, if we expect nr_hugepages to report the number of successfull= y >>>> allocated hugepages then we should use nr_huge_pages in >>>> hugetlb_sysctl_handler_common(). >>> This looks like a bug. Neither sysctl or the /proc file should be repo= rting >>> a non-zero value if huge pages do not exist. >> Yeap, as I mentioned it reports max_huge_pages instead of the nr_huge_pa= ges. > Does this only happen when you specify gigantic pages as the default huge > page size and they are not allocated at boot time? Yes. > Or, are there other > situations where this happens? If so, can you provide a sample of the > boot parameters used, or how to recreate. To reproduce this behavior boot the kernel with 'default_hugepagesz=3D1G hugepages=3D8' parameter in the kernel cmdline, hugepagesz needs to be skipped to ensure that no gigantic hugepages are allocated. After the kernel is up check the output of 'sysctl vm.nr_hugepages'. This should be good enough to reproduce this issue. > > I am fixing up the issue with gigantic pages, and suspect this will take > are of all the issues you are seeing. This will be part of the command l= ine > cleanup series. Just want to make sure I am not missing something. Makes sense. Thank you. --=20 Nitesh --IPsz3W7J0spvKcK1NCcJaLgHJcbQVPqQS-- --0dG372tR7vYXwb95lp3IL4xTLq1ddr9Ct Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkXcoRVGaqvbHPuAGo4ZA3AYyozkFAl6W9DAACgkQo4ZA3AYy ozmgMxAAsjHIF5TKLev1iZpUPzMNlIQAJAyAEczazQz2HJJ7REFOfWs2agnemGbD misO1NoIPtglDEr4Kqa1EF7ojT4aXkQ3zsyd2N3a0rnlD6jX/pE+sKNBmi3HFjft cQva3K8RVKCxUr4UbqcIudwfR1H/IPQ3MouqqvE3epZJ4uvhyUIct4n5pxQ5X4Ra BuIQfUo2eIWSsPvivgYUhzOO8qu8UOMvXWlvl1dSNbCcm5PlnlmMDkb6ntZOBg5e 4GYlyPAcHDlvwkiLphs5ePODiUFfLJbIE8QNbacBagZx2t5lx4Lx8k/4wVtZtxqE knD5FIW998VHABRzzxDemZ4M7c1nNas0jTlaOCLzPvNW31HaRjPi6gzHfJCJ1MFk j8/6yuuI3qwO3cqVA9b1NvZz/PVPJmNCf3Lnhi4NLaWWQoO4VASh+pE8zfEKdAAx ogA4l4b9JLsQfY0YYfNBPbGLPMmk7MAduJY0UFGFCgEtFppBJ9pxZ+OMkYOVFyKu uCytZCqik17mHECfGh4H3JxT0MSXWs4vN5FT+L3KmJQLgIF35Bs3YRxhAfiyk2E6 GRSskOOipJIG8BnP75LhiupzGSf8VA9Yy7kuLKLtCksJI0ANO9+hZZxamyu27Yz7 aZ6rQOTCYrUhXdfFFGYjPvT6xfbda3yTgFbL04fYpr8Ynj9gMhs= =FYpv -----END PGP SIGNATURE----- --0dG372tR7vYXwb95lp3IL4xTLq1ddr9Ct--