From mboxrd@z Thu Jan 1 00:00:00 1970 From: Austin S Hemmelgarn Subject: Re: [PATCH] mm-move-mremap-from-file_operations-to-vm_operations_struct-fix Date: Fri, 17 Jul 2015 14:39:14 -0400 Message-ID: <55A94BD2.5040603@gmail.com> References: <20150716231405.GA25147@redhat.com> <20150716162444.26425f5e227387f1166a6d16@linux-foundation.org> <20150716235227.GA26551@redhat.com> <20150717140615.GA2779@kvack.org> <20150717172726.GA30443@redhat.com> <20150717173757.GD2779@kvack.org> <20150717175542.GA31888@redhat.com> <55A94578.5050306@gmail.com> <20150717181940.GA946@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha1; boundary="------------ms080100000305000807000003" Return-path: Received: from mail-ie0-f174.google.com ([209.85.223.174]:34633 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752085AbbGQSjb (ORCPT ); Fri, 17 Jul 2015 14:39:31 -0400 In-Reply-To: <20150717181940.GA946@redhat.com> Sender: linux-next-owner@vger.kernel.org List-ID: To: Oleg Nesterov Cc: Benjamin LaHaise , Andrew Morton , Joonsoo Kim , Fengguang Wu , Jeff Moyer , Johannes Weiner , Stephen Rothwell , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org This is a cryptographically signed message in MIME format. --------------ms080100000305000807000003 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: quoted-printable On 2015-07-17 14:19, Oleg Nesterov wrote: > On 07/17, Austin S Hemmelgarn wrote: >> >> On 2015-07-17 13:55, Oleg Nesterov wrote: >>> On 07/17, Benjamin LaHaise wrote: >>>> >>>> Don't add BUG(). It's the equivalent approach of saying "I think th= is code >>>> isn't needed, but I'm lazy and not going to remove it properly." >>> >>> There is another interpretation: I think this code must be never call= ed, >>> if it is actually called we have a serious problem which should be lo= udly >>> reported. >>> >> And not compiling it at all _will_ loudly report it, it'll just report= >> it during linking instead of at run-time, which is a much better time = to >> shout about it. > > And how can we do this? > If a function that isn't defined (for example, you use a #if block to=20 comment it out under certain circumstances), then the link will fail=20 rather noisily something references it. We already know during the=20 compile that it's a NOMMU kernel, so anything that calls it on a MMU=20 enabled kernel can have a compile time check added instead of doing the=20 check at runtime (or even just calling it without checking), thus even=20 further reducing code size. --------------ms080100000305000807000003 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExCzAJBgUrDgMCGgUAMIAGCSqGSIb3DQEHAQAAoIIGuDCC BrQwggScoAMCAQICAxBuVTANBgkqhkiG9w0BAQ0FADB5MRAwDgYDVQQKEwdSb290IENBMR4w HAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmlu ZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZzAeFw0xNTAz MjUxOTM0MzhaFw0xNTA5MjExOTM0MzhaMGMxGDAWBgNVBAMTD0NBY2VydCBXb1QgVXNlcjEj MCEGCSqGSIb3DQEJARYUYWhmZXJyb2luN0BnbWFpbC5jb20xIjAgBgkqhkiG9w0BCQEWE2Fo ZW1tZWxnQG9oaW9ndC5jb20wggIiMA0GCSqGSIb3DQEBAQUAA4ICDwAwggIKAoICAQCdD/zW 2rRAFCLnDfXpWxU1+ODqRVUgzHvrRO7ADUxRo1CBDc3JSX5TIW2OGmQ3DAKGOACp8Z0sgxMc B05tzAZ/M7m4jajVrwwdVCdrwVGxTdAai7Kwg4ZCVfyMVhcwo8R2eW3QahBx34G0RKumK9sZ ZQSQ+zULAzpY6uz7T1sAk/erMoivRXF6u8WvOsLkOD1F/Xyv1ZccSUG5YeDgZgc0nZUBvyIp zXSHjgWerFkrxEM3y2z/Ff3eL1sgGYecV/I1F+I5S01V7Kclt/qRW10c/4JEGRcI1FmrJBPu BtMYPbg/3Y9LZROYN+mVIFxZxOfrmjfFZ96xt/TaMXo8vcEKtWcNEjhGBjEbfMUEm4aq8ygQ 4MuEcpJc8DJCHBkg2KBk13DkbU2qNepTD6Uip1C+g+KMr0nd6KOJqSH27ZuNY4xqV4hIxFHp ex0zY7mq6fV2o6sKBGQzRdI20FDYmNjsLJwjH6qJ8laxFphZnPRpBThmu0AjuBWE72GnI1oA aO+bs92MQGJernt7hByCnDO82W/ykbVz+Ge3Sax8NY0m2Xdvp6WFDY/PjD9CdaJ9nwQGsUSa N54lrZ2qMTeCI9Vauwf6U69BA42xgk65VvxvTNqji+tZ4aZbarZ7el2/QDHOb/rRwlCFplS/ z4l1f1nOrE6bnDl5RBJyW3zi74P6GwIDAQABo4IBWTCCAVUwDAYDVR0TAQH/BAIwADBWBglg hkgBhvhCAQ0ESRZHVG8gZ2V0IHlvdXIgb3duIGNlcnRpZmljYXRlIGZvciBGUkVFIGhlYWQg b3ZlciB0byBodHRwOi8vd3d3LkNBY2VydC5vcmcwDgYDVR0PAQH/BAQDAgOoMEAGA1UdJQQ5 MDcGCCsGAQUFBwMEBggrBgEFBQcDAgYKKwYBBAGCNwoDBAYKKwYBBAGCNwoDAwYJYIZIAYb4 QgQBMDIGCCsGAQUFBwEBBCYwJDAiBggrBgEFBQcwAYYWaHR0cDovL29jc3AuY2FjZXJ0Lm9y ZzAxBgNVHR8EKjAoMCagJKAihiBodHRwOi8vY3JsLmNhY2VydC5vcmcvcmV2b2tlLmNybDA0 BgNVHREELTArgRRhaGZlcnJvaW43QGdtYWlsLmNvbYETYWhlbW1lbGdAb2hpb2d0LmNvbTAN BgkqhkiG9w0BAQ0FAAOCAgEAGvl7xb42JMRH5D/vCIDYvFY3dR2FPd5kmOqpKU/fvQ8ovmJa p5N/FDrsCL+YdslxPY+AAn78PYmL5pFHTdRadT++07DPIMtQyy2qd+XRmz6zP8Il7vGcEDmO WmMLYMq4xV9s/N7t7JJp6ftdIYUcoTVChUgilDaRWMLidtslCdRsBVfUjPb1bF5Ua31diKDP e0M9/e2CU36rbcTtiNCXhptMigzuL3zJXUf2B9jyUV8pnqNEQH36fqJ7YTBLcpq3aYa2XbAH Hgx9GehJBIqwspDmhPCFZ/QmqUXCkt+XfvinQ2NzKR6P3+OdYbwqzVX8BdMeojh7Ig8x/nIx mQ+/ufstL1ZYp0bg13fyK/hPYSIBpayaC76vzWovkIm70DIDRIFLi20p/qTd7rfDYy831Hjm +lDdCECF9bIXEWFk33kA97dgQIMbf5chEmlFg8S0e4iw7LMjvRqMX3eCD8GJ2+oqyZUwzZxy S0Mx+rBld5rrN7LsXwZ671HsGqNeYbYeU25e7t7/Gcc6Bd/kPfA+adEuUGFcvUKH3trDYqNq 6mOkAd8WO/mQadlc3ztS++XDMhmIpfBre9MPAr6usqf+wc+R8Nk9KLK39kEgrqVfzc/fgf8L MaD4rHnusdg4gca6Yi+kNrm99anw7SwaBrBvULYBp7ixNRUhaYiNW4YjTrYxggShMIIEnQIB ATCBgDB5MRAwDgYDVQQKEwdSb290IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5v cmcxIjAgBgNVBAMTGUNBIENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEW EnN1cHBvcnRAY2FjZXJ0Lm9yZwIDEG5VMAkGBSsOAwIaBQCgggH1MBgGCSqGSIb3DQEJAzEL BgkqhkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTE1MDcxNzE4MzkxNFowIwYJKoZIhvcNAQkE MRYEFLVrEKDCHhSehNUCZbDEpBs3SJ01MGwGCSqGSIb3DQEJDzFfMF0wCwYJYIZIAWUDBAEq MAsGCWCGSAFlAwQBAjAKBggqhkiG9w0DBzAOBggqhkiG9w0DAgICAIAwDQYIKoZIhvcNAwIC AUAwBwYFKw4DAgcwDQYIKoZIhvcNAwICASgwgZEGCSsGAQQBgjcQBDGBgzCBgDB5MRAwDgYD VQQKEwdSb290IENBMR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMT GUNBIENlcnQgU2lnbmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2Fj ZXJ0Lm9yZwIDEG5VMIGTBgsqhkiG9w0BCRACCzGBg6CBgDB5MRAwDgYDVQQKEwdSb290IENB MR4wHAYDVQQLExVodHRwOi8vd3d3LmNhY2VydC5vcmcxIjAgBgNVBAMTGUNBIENlcnQgU2ln bmluZyBBdXRob3JpdHkxITAfBgkqhkiG9w0BCQEWEnN1cHBvcnRAY2FjZXJ0Lm9yZwIDEG5V MA0GCSqGSIb3DQEBAQUABIICAEIVwk87GD5g4TR2cxIDl1YEjgfgZjxLpf/RDh4az6sPJV68 csZ0Kx39l8RhmkfNYhtGr58HlldTEJSlXnzgbtIVFibPKK4RDu4Gjid5/iuIDWqExvrowjL9 FsjrC8/btCUkaQnSWr29xkEG8YCp06Kg18z+xD0rJlqC96pMk1EN7jHtKjgiowdK924T/qwh 43SSxrH+Z6fN/nje5OSWmKNoHvy8PO7k/TLSZUq70UlRamGTtmDUQV5d4eFRAnYSgca6t5Fr yqZpdflhJnOpKfUqc2viWwiH7LeqKx2FgKNN744NRUNUpbbT5QAhsyBBOKz/QHiOzppMnH1Z GQExnjLBCraGgzf0uHWz+8L6ZF1DHUzf+BNfdlJAtkjy1w3sQD6paCD+kVXqPUtjMzZADUwy VhFMozWUAMldNgV0X0HcqYkonxAQXFtPt6a0oWIixJQQk1HdY3/Ovu97GR+YMYeRLduF8zMM 9VFmvjyHsD7zi5uve/8U72BsCJfVNvksRc1Gtkj8zfedw15VoZ4g8OXhFwdhQv373tNZP55I OEivqVV2XrdxkhMq9aNny17Cq5htekNGjzVV2zBjABO1b5KEaRzT1W2k9gfhSIxIVueQw6or TvkB/D4I4z/MF1T3/HmB9N1Ldo3z0llG9qzx+FLKXQQYcemKxf2jUlSfi+ThAAAAAAAA --------------ms080100000305000807000003--