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Shutemov" CC: LKML , Linux-MM , "oleg@redhat.com" , "rostedt@goodmis.org" , "mhiramat@kernel.org" , "matthew.wilcox@oracle.com" , "kirill.shutemov@linux.intel.com" , "Kernel Team" Subject: Re: [PATCH v4 5/5] uprobe: collapse THP pmd after removing all uprobes Thread-Topic: [PATCH v4 5/5] uprobe: collapse THP pmd after removing all uprobes Thread-Index: AQHVIhGkBNxZAI1nUkK1d2OfbYvmTqamGxWAgAAIBYCAAAVYgIAAAncAgAAuG4A= Date: Fri, 21 Jun 2019 16:30:04 +0000 Message-ID: <707D52CA-E782-4C9A-AC66-75938C8E3358@fb.com> References: <20190613175747.1964753-1-songliubraving@fb.com> <20190613175747.1964753-6-songliubraving@fb.com> <20190621124823.ziyyx3aagnkobs2n@box> <20190621133613.xnzpdlicqvjklrze@box> <4B58B3B3-10CB-4593-8BEC-1CEF41F856A1@fb.com> In-Reply-To: <4B58B3B3-10CB-4593-8BEC-1CEF41F856A1@fb.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-mailer: Apple Mail (2.3445.104.11) x-originating-ip: [2620:10d:c090:200::1:e314] x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 637ab245-7cc0-476e-1212-08d6f665b71d x-microsoft-antispam: BCL:0;PCL:0;RULEID:(2390118)(7020095)(4652040)(8989299)(5600148)(711020)(4605104)(1401327)(4534185)(4627221)(201703031133081)(201702281549075)(8990200)(2017052603328)(7193020);SRVR:MWHPR15MB1616; x-ms-traffictypediagnostic: MWHPR15MB1616: x-microsoft-antispam-prvs: x-ms-oob-tlc-oobclassifiers: OLM:8882; x-forefront-prvs: 0075CB064E x-forefront-antispam-report: SFV:NSPM;SFS:(10019020)(39860400002)(396003)(376002)(366004)(346002)(136003)(199004)(189003)(5660300002)(76116006)(73956011)(256004)(50226002)(6246003)(54906003)(6916009)(33656002)(102836004)(186003)(76176011)(53546011)(6506007)(478600001)(25786009)(66946007)(486006)(4326008)(66556008)(66446008)(64756008)(66476007)(2906002)(7736002)(57306001)(81156014)(14454004)(46003)(81166006)(99286004)(316002)(476003)(8676002)(53936002)(6512007)(6486002)(6116002)(36756003)(2616005)(11346002)(229853002)(71200400001)(71190400001)(6436002)(68736007)(446003)(86362001)(8936002)(305945005);DIR:OUT;SFP:1102;SCL:1;SRVR:MWHPR15MB1616;H:MWHPR15MB1165.namprd15.prod.outlook.com;FPR:;SPF:None;LANG:en;PTR:InfoNoRecords;A:1;MX:1; received-spf: None (protection.outlook.com: fb.com does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 x-microsoft-antispam-message-info: aQa6KhLL3tB5eksbA19jSs8upkISddY089JT1IO6zWnJlvIip9I1FMsDjUnVAOdG8LluV5BRIBl2eDqRXy/HEc5yyOwZNFkxFDF2D3VkYJUMp4vqTj4xXAOx0xV0dL3sNlP9Hm9M4V4R8M9zj3jfTOb1FeZmLubnyefbEsjlpwqWO0bbOyWU9y+Ges4Wyhfyxv66xSPku8WrbrGpUODwQaDEAhHV2W1wS6cgndnW6nithhAygoVQhAtAs7DMTN3j3LlZC2/DoX20ixRVQ/OsYfUXaIidUlaNd/P/aotdEwSF/g+t/QypzFe40CeEm91mD6L2jyvKVw+dW5k2p272T5nN+h2MzaaBe7IrpagF8CzX8c8SETdJ/eFP7/6tW0UxfZ7ZpCyweUiC+8cdoI+JNNe0ckd77J2uMOl6hrOpYCA= Content-Type: text/plain; charset="us-ascii" Content-ID: <274FD60A5325DD41BC5BD6A652FD3B91@namprd15.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-MS-Exchange-CrossTenant-Network-Message-Id: 637ab245-7cc0-476e-1212-08d6f665b71d X-MS-Exchange-CrossTenant-originalarrivaltime: 21 Jun 2019 16:30:04.1697 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: songliubraving@fb.com X-MS-Exchange-Transport-CrossTenantHeadersStamped: MWHPR15MB1616 X-OriginatorOrg: fb.com X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-06-21_11:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=706 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906210132 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Jun 21, 2019, at 6:45 AM, Song Liu wrote: >=20 >=20 >=20 >> On Jun 21, 2019, at 6:36 AM, Kirill A. Shutemov w= rote: >>=20 >> On Fri, Jun 21, 2019 at 01:17:05PM +0000, Song Liu wrote: >>>=20 >>>=20 >>>> On Jun 21, 2019, at 5:48 AM, Kirill A. Shutemov = wrote: >>>>=20 >>>> On Thu, Jun 13, 2019 at 10:57:47AM -0700, Song Liu wrote: >>>>> After all uprobes are removed from the huge page (with PTE pgtable), = it >>>>> is possible to collapse the pmd and benefit from THP again. This patc= h >>>>> does the collapse. >>>>>=20 >>>>> An issue on earlier version was discovered by kbuild test robot. >>>>>=20 >>>>> Reported-by: kbuild test robot >>>>> Signed-off-by: Song Liu >>>>> --- >>>>> include/linux/huge_mm.h | 7 +++++ >>>>> kernel/events/uprobes.c | 5 ++- >>>>> mm/huge_memory.c | 69 ++++++++++++++++++++++++++++++++++++++++= + >>>>=20 >>>> I still sync it's duplication of khugepaged functinallity. We need to = fix >>>> khugepaged to handle SCAN_PAGE_COMPOUND and probably refactor the code= to >>>> be able to call for collapse of particular range if we have all locks >>>> taken (as we do in uprobe case). >>>>=20 >>>=20 >>> I see the point now. I misunderstood it for a while.=20 >>>=20 >>> If we add this to khugepaged, it will have some conflicts with my other= =20 >>> patchset. How about we move the functionality to khugepaged after these >>> two sets get in?=20 >>=20 >> Is the last patch of the patchset essential? I think this part can be do= ne >> a bit later in a proper way, no? >=20 > Technically, we need this patch to regroup pmd mapped page, and thus get= =20 > the performance benefit after the uprobe is detached.=20 >=20 > On the other hand, if we get the first 4 patches of the this set and the= =20 > other set in soonish. I will work on improving this patch right after tha= t.. Actually, it might be pretty easy. We can just call try_collapse_huge_pmd()= =20 in khugepaged.c (in khugepaged_scan_shmem() or khugepaged_scan_file() after= =20 my other set).=20 Let me fold that in and send v5.=20 Thanks, Song