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b=mj8+82IgGzyI6MJVVLBy57BfvzFo3eflS+GZ+P1hZLQt56+SpuW1qDVqN8T/4ok0o Bo/rnJCkRFxA2hHtsudRKnNMpNYNBdWsAmqfrIlIfhZc6vHsQIb+ZAhvYwZS2jZXLM wWtnZJhzQS+BE7Rdsf9bzz9zjQkPcsWgu2dBs6CjaDd/qr8NqBAXklQ8EJcKKwXa9n eeu5Nk2sTeurjCq3HR22POQH3xW9KiCL/0feoY5DwVCs5gR6vM3oY8Mf+mfvpsaFmN PhQ4IDgGm70galBMIGm9sKMnra1XxFhBP8QX6JfIgJE+Pfho5g5dqLokt2mrFwSNH4 PBc5rPqWtN5pw== Message-ID: <3424eba7-523b-4351-abd0-3a888a3e5e61@kernel.org> Date: Wed, 4 Feb 2026 22:08:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/9] mm/memory_hotplug: add __add_memory_driver_managed() with online_type arg To: Gregory Price , Jonathan Cameron Cc: linux-mm@kvack.org, linux-cxl@vger.kernel.org, nvdimm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, kernel-team@meta.com, dave@stgolabs.net, dave.jiang@intel.com, alison.schofield@intel.com, vishal.l.verma@intel.com, ira.weiny@intel.com, dan.j.williams@intel.com, willy@infradead.org, jack@suse.cz, terry.bowman@amd.com, john@jagalactic.com, Oscar Salvador , Andrew Morton References: <20260129210442.3951412-1-gourry@gourry.net> <20260129210442.3951412-3-gourry@gourry.net> <20260202172524.00000c6d@huawei.com> <20260202184609.00004a02@huawei.com> From: "David Hildenbrand (arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 678CE140007 X-Stat-Signature: s5gzfz1x3oncady9t58e98dq6tghuz9s X-Rspam-User: X-HE-Tag: 1770239334-981186 X-HE-Meta: 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 2vrSycVr vryl6 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 2/2/26 22:37, Gregory Price wrote: > On Mon, Feb 02, 2026 at 06:46:09PM +0000, Jonathan Cameron wrote: >>> >>> I can add a cleanup-patch prior to use the enum, but i don't think this >>> actually enables the compiler to do anything new at the moment? >> >> Good point. More coffee needed (or sleep) >> >> It lets sparse do some checking, but sadly only for wrong enum assignment. >> (Gcc has -Wenum-conversion as well which I think is effectively the same) >> I.e. you can't assign a value from a different enum without casting. >> >> It can't do anything if people just pass in an out of range int. >> > > Which, after looking a bit... mm/memory_hotplug.c does this quite a bit > internally - except it uses a uint8_t > > Example: > > static int try_offline_memory_block(struct memory_block *mem, void *arg) > { > uint8_t online_type = MMOP_ONLINE_KERNEL; > uint8_t **online_types = arg; > ... snip ... > } > > int offline_and_remove_memory(u64 start, u64 size) > { > uint8_t *online_types, *tmp; > ... snip ... > online_types = kmalloc_array(mb_count, sizeof(*online_types), > GFP_KERNEL); > } > > So that's fun. > > I'm not sure it's worth the churn here, but happy to do it if there are > strong opinions. > > --- > > David do you have thoughts here? I guess we should clean that all up where easily possible, but I don't expect you to do that. For online_types I used it, obviously, to save memory. So I'd expect it to stay at least there, but cast it to the proper type once we take it out the array. -- Cheers, David