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From: Aneesh Kumar K V <aneesh.kumar@linux.ibm.com>
To: "Verma, Vishal L" <vishal.l.verma@intel.com>,
	"Williams, Dan J" <dan.j.williams@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	"osalvador@suse.de" <osalvador@suse.de>,
	"david@redhat.com" <david@redhat.com>,
	"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Cc: "Hocko, Michal" <mhocko@suse.com>,
	"Huang, Ying" <ying.huang@intel.com>,
	"Jonathan.Cameron@Huawei.com" <Jonathan.Cameron@Huawei.com>,
	"linux-cxl@vger.kernel.org" <linux-cxl@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"jmoyer@redhat.com" <jmoyer@redhat.com>,
	"dave.hansen@linux.intel.com" <dave.hansen@linux.intel.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"nvdimm@lists.linux.dev" <nvdimm@lists.linux.dev>
Subject: Re: [PATCH v4 2/2] dax/kmem: allow kmem to add memory with memmap_on_memory
Date: Wed, 4 Oct 2023 10:42:20 +0530	[thread overview]
Message-ID: <6e636e70-cbe5-45a7-8918-abdf196d5437@linux.ibm.com> (raw)
In-Reply-To: <e1600e8d3986b1ed371847d4863628b8d7ad2091.camel@intel.com>

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


      reply	other threads:[~2023-10-04  5:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-28 20:30 [PATCH v4 0/2] mm: use memmap_on_memory semantics for dax/kmem Vishal Verma
2023-09-28 20:30 ` [PATCH v4 1/2] mm/memory_hotplug: split memmap_on_memory requests across memblocks Vishal Verma
2023-10-02  9:28   ` David Hildenbrand
2023-10-03 20:03     ` Verma, Vishal L
2023-10-06 12:33       ` David Hildenbrand
2023-09-28 20:30 ` [PATCH v4 2/2] dax/kmem: allow kmem to add memory with memmap_on_memory Vishal Verma
2023-10-02  9:21   ` David Hildenbrand
2023-10-03  4:04   ` Aneesh Kumar K V
2023-10-03 23:48     ` Verma, Vishal L
2023-10-04  5:12       ` Aneesh Kumar K V [this message]

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