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Shutemov" , x86@kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Dan Williams , Kai Huang , "H. Peter Anvin" , Andy Lutomirski , Oscar Salvador Subject: Re: [PATCH -V2] tdx, memory hotplug: Check whole hot-adding memory range for TDX In-Reply-To: <037801d9-8923-4d49-8423-072fd7c73069@redhat.com> (David Hildenbrand's message of "Thu, 10 Oct 2024 14:40:47 +0200") References: <20241010074726.1397820-1-ying.huang@intel.com> <037801d9-8923-4d49-8423-072fd7c73069@redhat.com> Date: Fri, 11 Oct 2024 09:27:16 +0800 Message-ID: <87o73ra0p7.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Stat-Signature: odn7zzsz6smxdgkz9nbdbz564ort44ro X-Rspamd-Queue-Id: 9C636140003 X-Rspam-User: X-Rspamd-Server: rspam10 X-HE-Tag: 1728610253-147446 X-HE-Meta: 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 2KanqoXg A5jk3HOzVHc6my5KydDji+1PomeAECRMnn0rSriwXd/Fbb1x1cCFxsRFsK9QSwkG6regiVvJNqx+xUFs4U74XzgzerAeu5yc8Dpie5T9m37Rbkj/5Czap9F1k055ZmcF5gUSwBYHlaC9ggODQ3UqVV54SzqFe5+jiDgaqlVyuTHZgdNu1ZEdEomwE/wemQqhD/QxP 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: David Hildenbrand writes: >> extern u64 max_mem_size; >> extern int mhp_online_type_from_str(const char *str); >> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >> index 621ae1015106..c4769f24b1e2 100644 >> --- a/mm/memory_hotplug.c >> +++ b/mm/memory_hotplug.c >> @@ -1305,6 +1305,11 @@ int try_online_node(int nid) >> return ret; >> } >> +int __weak arch_check_hotplug_memory_range(u64 start, u64 size) >> +{ >> + return 0; >> +} > > BTW, I remember that "__weak" doesn't always behave the way it would > seem, which is the reason we're usually using > > #define arch_check_hotplug_memory_range arch_check_hotplug_memory_range > > #ifndef arch_check_hotplug_memory_range > ... > #endif > > > Not that I remember the details, just that it can result in rather > surprising outcomes (e.g., the wrong function getting called). I can replace __weak with #define/#ifndef. However, it appears that "__weak" is still widely used now. $ grep __weak -r mm kernel init | wc -l 231 -- Best Regards, Huang, Ying