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Wed, 4 Oct 2023 05:12:23 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7F06A20043; Wed, 4 Oct 2023 05:12:23 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2738220040; Wed, 4 Oct 2023 05:12:21 +0000 (GMT) Received: from [9.109.212.144] (unknown [9.109.212.144]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 4 Oct 2023 05:12:20 +0000 (GMT) Message-ID: <6e636e70-cbe5-45a7-8918-abdf196d5437@linux.ibm.com> Date: Wed, 4 Oct 2023 10:42:20 +0530 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 2/2] dax/kmem: allow kmem to add memory with memmap_on_memory Content-Language: en-US To: "Verma, Vishal L" , "Williams, Dan J" , "Jiang, Dave" , "osalvador@suse.de" , "david@redhat.com" , "akpm@linux-foundation.org" Cc: "Hocko, Michal" , "Huang, Ying" , "Jonathan.Cameron@Huawei.com" , "linux-cxl@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "jmoyer@redhat.com" , "dave.hansen@linux.intel.com" , "linux-mm@kvack.org" , "nvdimm@lists.linux.dev" References: <20230928-vv-kmem_memmap-v4-0-6ff73fec519a@intel.com> <20230928-vv-kmem_memmap-v4-2-6ff73fec519a@intel.com> <73bdc58d-edc1-4344-b42a-4b83ca885329@linux.ibm.com> From: Aneesh Kumar K V In-Reply-To: Content-Type: text/plain; charset=UTF-8 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: lwr6gmcUVDz9kvKRX2_JLfm8fM4InJpt X-Proofpoint-ORIG-GUID: q9xukhjGvTEJd5H1i7EYqmnB_Vay5YoE Content-Transfer-Encoding: 7bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.267,Aquarius:18.0.980,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-10-04_01,2023-10-02_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 mlxlogscore=664 malwarescore=0 impostorscore=0 adultscore=0 bulkscore=0 suspectscore=0 clxscore=1015 mlxscore=0 phishscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2309180000 definitions=main-2310040035 X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 8DE8640004 X-Stat-Signature: rtyanhfk8oby4qmqrpdeedpmhcc8o9wu X-HE-Tag: 1696396362-719444 X-HE-Meta: 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 eocDh8MF fU4Ng7wtymQqDNOlLd/l5kov3NUtewkXj+l5oLis3QK4F+MUYe3FQgd+tdWkbx/nny9Ls0mwo6zMru95UMTWMGiCqTjMreOSVW3L8c26cQ7Pb3NJ7gZCjK77SJqEEqd0VUVOo78o5XU/aEyUykagB57SNrn33ENJvWfuK4EAayypQ/AFIH8DOYarrzRWbMZ1OC3XCcfCdyJNrx8ppFM5EuQ+BL7dpnxMQF5l86cKQrPcrUvD4Q+OIA67E26YhFoEzP3q2UtbgXCyZ+D1mCfHSxi36EfLOOWpL2tT0jKeqyeH595WwnNbF96dMUIt0AP1zv4KJ9bJJMjWUDXQGVaEIOmEtn6qPYThkLcOr64jAolKPoHjmHr0vWdrWrAcnLO5275oYWJQEmfhgB+CuVg2iK+4OHulftoUfgpXViV0TI9KOevQhcpmf/lDzC5YY8dGjN0S/Ao6lELOBGLI= 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: On 10/4/23 5:18 AM, Verma, Vishal L wrote: > On Tue, 2023-10-03 at 09:34 +0530, Aneesh Kumar K V wrote: >> On 9/29/23 2:00 AM, Vishal Verma wrote: >>> Large amounts of memory managed by the kmem driver may come in via CXL, >>> and it is often desirable to have the memmap for this memory on the new >>> memory itself. >>> >>> Enroll kmem-managed memory for memmap_on_memory semantics if the dax >>> region originates via CXL. For non-CXL dax regions, retain the existing >>> default behavior of hot adding without memmap_on_memory semantics. >>> >> >> Are we not looking at doing altmap space for CXL DAX regions? Last discussion around >> this was suggesting we look at doing this via altmap reservation so that >> we get contigous space for device memory enabling us to map them >> via 1G direct mapping entries? >> > Hey Aneesh - was this on a previous posting or something - do you have > a link so I can refresh myself on what the discussion was? > > If it is enabling something in CXL similar to the --map=mem mode for > pmem + device dax, that could be incremental to this. Yes. Agree that we can do that incremental to this. https://lore.kernel.org/linux-mm/b6753402-2de9-25b2-36e9-eacd49752b19@redhat.com -aneesh