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Fri, 10 Apr 2020 11:57:05 +0000 (UTC) Received: from [10.10.112.152] (ovpn-112-152.rdu2.redhat.com [10.10.112.152]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 0C3FD9DD96; Fri, 10 Apr 2020 11:57:01 +0000 (UTC) Subject: Re: [PATCH] Documentation: hugetlb: Update hugetlb options To: Peter Xu , linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Mike Kravetz References: <20200409215800.8967-1-peterx@redhat.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: <465b3e80-d8db-510d-f005-7f1cc7831e6f@redhat.com> Date: Fri, 10 Apr 2020 07:57:00 -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: <20200409215800.8967-1-peterx@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0XjUQfG032zRm6QmnPWsuePcT6inCQ8ks" 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: This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --0XjUQfG032zRm6QmnPWsuePcT6inCQ8ks Content-Type: multipart/mixed; boundary="1lLocalmcbgyNm1E0Ukp1K5jm2SWOF4U6" --1lLocalmcbgyNm1E0Ukp1K5jm2SWOF4U6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Content-Language: en-US On 4/9/20 5:58 PM, Peter Xu wrote: > The hugepage options are not documented clearly. > > Firstly, default_hugepagesz=3D should always be specified after the > declaration of the same type of huge page using hugepagesz=3D. For > example, if we boot a x86_64 system with kernel cmdline > "default_hugepagesz=3D2M", we'll get a very funny error message: > > "HugeTLB: unsupported default_hugepagesz 2097152. Reverting to 2097152" There is an ongoing discussion to fix this issue. AFAIK it has not been settled yet and Mike was going to post a patch-set. https://lkml.org/lkml/2020/3/9/96 > > It's understandable from code-wise because when hugetlb_init() we > didn't have the 2M page hstate registered, so it's unsupported. > However 2M is actually the default huge page size on x86_64, so we'll > register it right after the error message. However it's very > confusing if without these knowledges. > > Secondly, hugepages=3D option must be used _after_ another hugepagesz=3D. > The word "interleave" is fine but it didn't declare the fact that > each of the hugepages=3D option will be applied to the previous parsed > hugepagesz=3D option. > > State all these clear. > > Signed-off-by: Peter Xu > --- > .../admin-guide/kernel-parameters.txt | 19 ++++++++++++------- > 1 file changed, 12 insertions(+), 7 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentat= ion/admin-guide/kernel-parameters.txt > index 86aae1fa099a..2a77b2b01e5e 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -839,7 +839,8 @@ > =09=09=09the legacy /proc/ hugepages APIs, used for SHM, and > =09=09=09default size when mounting hugetlbfs filesystems. > =09=09=09Defaults to the default architecture's huge page size > -=09=09=09if not specified. > +=09=09=09if not specified. This option can only be used with a > +=09=09=09pre-defined "hugepagesz=3D" of the same size. > =20 > =09deferred_probe_timeout=3D > =09=09=09[KNL] Debugging option to set a timeout in seconds for > @@ -1475,13 +1476,17 @@ > =09hpet_mmap=3D=09[X86, HPET_MMAP] Allow userspace to mmap HPET > =09=09=09registers. Default set by CONFIG_HPET_MMAP_DEFAULT. > =20 > +=09hugepagesz=3D=09[HW,IA-64,PPC,X86-64] Declare one type of HugeTLB pag= es > +=09=09=09with the size specified. Valid pages sizes on x86-64 > +=09=09=09are 2M (when the CPU supports "pse") and 1G (when the > +=09=09=09CPU supports the "pdpe1gb" cpuinfo flag). > + > =09hugepages=3D=09[HW,X86-32,IA-64] HugeTLB pages to allocate at boot. > -=09hugepagesz=3D=09[HW,IA-64,PPC,X86-64] The size of the HugeTLB pages. > -=09=09=09On x86-64 and powerpc, this option can be specified > -=09=09=09multiple times interleaved with hugepages=3D to reserve > -=09=09=09huge pages of different sizes. Valid pages sizes on > -=09=09=09x86-64 are 2M (when the CPU supports "pse") and 1G > -=09=09=09(when the CPU supports the "pdpe1gb" cpuinfo flag). > +=09=09=09On x86-64 and powerpc, this option must be used after > +=09=09=09one hugepagesz=3D to allocate huge pages of that specific > +=09=09=09size. This option can also be used multiple times > +=09=09=09pairing with hugepagesz=3D to allocate huge pages for > +=09=09=09different sizes. > =20 > =09hung_task_panic=3D > =09=09=09[KNL] Should the hung task detector generate panics. --=20 Nitesh --1lLocalmcbgyNm1E0Ukp1K5jm2SWOF4U6-- --0XjUQfG032zRm6QmnPWsuePcT6inCQ8ks Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkXcoRVGaqvbHPuAGo4ZA3AYyozkFAl6QXwwACgkQo4ZA3AYy ozkkGxAA0cf0ab+K20o7f9ds/YZFMWjQK+UyK6GHMqUSDMOOWFBMHaUkS0a3Pxsf 4sRv26WVKVVDOEgmo5J8Ljl/1eJt8//a6smWPnuk+SbstNHfEvSzgLHB9eNWjyYg Eqn10Fqt5c9xKCfPGDY/Sh3ysjpOQXg9Kp162QcdNoW8CW4Rl1eQq/d7ic9o89v5 eHP2Uann8jgYdQJm5MZGQ5AoIENWBy41r7lK8KR9EphGsFb/n0ciOcvDPoamT7JW aR/yCnOE93ZA44uByu3asleDgzWLvNkrDi5/NccjLv0u9c+ap/BzaITMJWhZSflI T+isj8WNaPOH3na2ApFLF3Pwa09kfMVtOCb/rnm1cTDBJku2cTcy1u16Ft0pzcU4 oan35BewIjcAyKI8Avs/x3CDHmxLMLKIczdvPl54fkau6LzzVODaVCQ+CRdVFCpL NQICH0iGdoGQ9ZyW8PBIign8iSBcpK22f6E1wJFkKpOT9LULyRE3NIWoCWYhiq5c X7AzdXb1rn2szmYlI78OaTqIh23XlKhNxdE+qUn/07OC/TJFMA0Zts4WrzkshWSu TfzxYsY5CA3Y9GZm8AbIq58ygePQKcgsg1q1Vu6wweCe7+C0S+9FjZBjT5YVXooe o6dZYjOf71Hlg7mMT17Fv08CVIl9HCs/5ImuSHpVnWZP3aZg9PE= =48iJ -----END PGP SIGNATURE----- --0XjUQfG032zRm6QmnPWsuePcT6inCQ8ks--