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bh=p577qqkGNM+YtsoofFUL3UzNKI8twXildO3X6IpGT8g=; b=2jT9MjGPCkxH5/ZyAOQq+U7dMQsebfP1QferJOwLEYukLkTY71Lgw5/1h4VaKi+7gsnQPs qZfxLHmnt1BhwMpyPj5dTBvllx0ZVP6vFtPwxxJV8zno0ZJPJ/XPIBIN7TR2ZsVoz5eN8P DZrPn/3CU0l/M8y5L7VpQT7DtLV1zOU= X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 4145A1A0085 X-Stat-Signature: r9xu9qcn9q5mwzoqna49qmiym9oigb1o X-Rspam-User: Authentication-Results: imf19.hostedemail.com; dkim=pass header.d=suse.de header.s=susede2_rsa header.b=oODkKERJ; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=Hex085tR; spf=pass (imf19.hostedemail.com: domain of osalvador@suse.de designates 195.135.220.29 as permitted sender) smtp.mailfrom=osalvador@suse.de; dmarc=pass (policy=none) header.from=suse.de X-HE-Tag: 1655109232-234260 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 Mon, Jun 13, 2022 at 02:35:12PM +0800, Muchun Song wrote: > -static __init int hugetlb_vmemmap_sysctls_init(void) > +static int __init hugetlb_vmemmap_init(void) > { > + const struct hstate *h; > + bool optimizable = false; > + > /* > - * If "struct page" crosses page boundaries, the vmemmap pages cannot > - * be optimized. > + * There are only (RESERVE_VMEMMAP_SIZE / sizeof(struct page)) struct > + * page structs that can be used when HVO is enabled. > */ > - if (is_power_of_2(sizeof(struct page))) > - register_sysctl_init("vm", hugetlb_vmemmap_sysctls); > + BUILD_BUG_ON(__NR_USED_SUBPAGE >= RESERVE_VMEMMAP_SIZE / sizeof(struct page)); I need to take another look, but from the first glance there is something here that caught my eye. > + > + for_each_hstate(h) { > + char buf[16]; > + unsigned int size = 0; > + > + if (hugetlb_vmemmap_optimizable(h)) > + size = hugetlb_vmemmap_size(h) - RESERVE_VMEMMAP_SIZE; > + optimizable = size ? true : optimizable; This feels weird, just use false instead of optimizable. > + string_get_size(huge_page_size(h), 1, STRING_UNITS_2, buf, > + sizeof(buf)); > + pr_info("%d KiB vmemmap can be optimized for a %s page\n", > + size / SZ_1K, buf); I do not have a strong opinion but I wonder whether this brings a lot. -- Oscar Salvador SUSE Labs