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Fri, 23 Jan 2026 18:25:27 +0000 Date: Fri, 23 Jan 2026 18:25:26 +0000 From: Jonathan Cameron To: Gregory Price CC: "David Hildenbrand (Red Hat)" , , , , , , , , , , , , , , , Subject: Re: [PATCH 3/8] mm/memory_hotplug: add APIs for explicit online type control Message-ID: <20260123182526.00005ee8@huawei.com> In-Reply-To: References: <20260114085201.3222597-1-gourry@gourry.net> <20260114085201.3222597-4-gourry@gourry.net> <4520e7b0-8218-404d-8ede-e62d95c50825@kernel.org> X-Mailer: Claws Mail 4.3.0 (GTK 3.24.42; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.203.177.15] X-ClientProxiedBy: lhrpeml500009.china.huawei.com (7.191.174.84) To dubpeml500005.china.huawei.com (7.214.145.207) X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: EA6241C000B X-Stat-Signature: tjgxjxftyhc5chd6488kcartsfcht3zn X-HE-Tag: 1769192732-98700 X-HE-Meta: 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 JZCo1eH1 sHh6hu7f+IXJu/SQVFuiJaN/LeRrOGdr3IB3Q6dx8Y1Ufj7gBFZ+SeUzgwjad3xbp6+FE/wwAMfy6WLgDQgtm4dunQJHya6/eMnJVEE55eL8JtSvjRGhaq9Cx1AikVjOJECvJGXjWCmwelWgqWALIvXW84JS4znU0po1nfeDVYuD3yqnCKrRMKHNSgyg6AXAP29ef0n7tUA8RzFM+KSLKoYfS8M9sbZDiaq9xtRZOt4UMOLmhIRD0DV9iFgjs8359/+3nfaFkEG7gvtkLAKG7LcIRGD5uCZl+vDrr53r/Z4Z3ScDr0yG/rrJ8yDEE8GnWWrEBp9NdXg0CEwI= 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: List-Subscribe: List-Unsubscribe: On Thu, 22 Jan 2026 19:34:10 -0500 Gregory Price wrote: > On Thu, Jan 22, 2026 at 11:41:24PM +0100, David Hildenbrand (Red Hat) wrote: > > > > Right, but I don't want any other OOT kernel module to be able to make use > > of add_memory_driver_managed() to do arbitrary things, because we don't know > > if it's really user space setting the policy for that memory then. > > > > Ah, this was lost on me. > > > So either restrict add_memory_driver_managed() to kmem+virtio_mem > > completely, or add another variant that will be kmem-only (or however that > > dax/cxl module is called). > > unclear to me how to restrict a function to specific drivers, but i can > add add_and_online_memory_driver_managed() trivially so no big issue. Is EXPORT_SYMBOL_GPL_FOR_MODULE() enough? > > You'd be ok with with this? > > add_and_online_memory_driver_managed(..., online_type) { > ... existing add_memory_driver_managed() code ... > } > > add_memory_driver_managed(...) { > add_and_online_memory_driver_managed(..., mhp_get_default_policy()); > } > > ~Gregory >