From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id C5CA5606A331 for ; Sat, 7 Nov 2026 07:02:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=I3yQwc+n Received: by kanga.kvack.org (Postfix) id C80BC6B05B0; Sat, 7 Nov 2026 02:02:18 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id C0CA06B05B1; Sat, 7 Nov 2026 02:02:18 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id AD32C6B05B2; Sat, 7 Nov 2026 02:02:18 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 839BD6B05B0 for ; Sat, 7 Nov 2026 02:02:18 -0500 (EST) Received: from smtpin07.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id E4D46C02A6 for ; Sat, 7 Nov 2026 07:02:17 +0000 (UTC) X-FDA: 85407429114.07.927C99C Received: from mta0.migadu.com (out-211.mta0.migadu.com [91.218.175.211]) by imf14.hostedemail.com (Postfix) with ESMTP id D69FF100002 for ; Sat, 7 Nov 2026 07:02:15 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=I3yQwc+n; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf14.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.211 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794034936; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=SNyW7L7svCZC+4vm04JJa3Y3COX/LWxh617gbF6SI0E=; b=X6cIAD1AIR91tvcuGbPGyjmft0iGQpCZx5PtDyPCZVqfG6wJMnhfCZcd0GxO3oM2TFSvCk MWpUb4EojBfWC1LwNnUCiOUmGlWEScmpIP71qFFxtY/CPOOJ9+346SZG4GDK6bKYP9dIpS fGBZ+6WSjDQtZ/q8ai48HLC8Xg7a2YU= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=I3yQwc+n; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf14.hostedemail.com: domain of muchun.song@linux.dev designates 91.218.175.211 as permitted sender) smtp.mailfrom=muchun.song@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794034936; b=oZhsTjNaepMAZEcPkknYN5+3rYsLY13wW4gT4YArBk1cDNH8As6F56/GdGF/cwUaCHz+Sh OZYy3fr5MSPLrHgdDg7glzPcRLQRVoePdYe8EtkQ4DAL+KarzRn6biA4CWSO88ICOYz6zF jkoNHUpfDnSr4nLdauwQTslha6UIGcc= X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=1eU8LB4FiA31cEPkSs3z/GNpYbcTIlce7/3o/u8t5mo=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794034934; v=1; x=1794639734; b=I3yQwc+nnr9dZ9rJHoIeeQfQUjIaGc2f/SLqKrFxDV2I480KdIkDlwFLnBpoNmKhbVN3fUXJ 61MUGbXwbuS+9RE94YjhsGLI1nsOE0EUWlJkqkywRE5Q624MjkvGo6fGlaAjtrHSpshsbklTY2m LIEKSxp9znNWy0ITPbV6NfYw= X-Envelope-To: linux-mm@kvack.org Received: by mta10.migadu.com with ESMTPS id 89d1383c0cbcfc28; Sat, 07 Nov 2026 07:02:14 +0000 X-Mizu-Trace-ID: 89d1383c0cbcfc28 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii X-Archived-By: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3901.200.71.1.16\)) Subject: Re: [PATCH v2 07/20] hugetlb_vmemmap: Disable HVO sysctl if arch doesn't support HVO From: Muchun Song In-Reply-To: <20261003002123.505555-8-jthoughton@google.com> Date: Sat, 7 Nov 2026 15:01:47 +0800 Cc: Will Deacon , Catalin Marinas , Oscar Salvador , Andrew Morton , Nikos Nikoleris , Linu Cherian , Mark Rutland , David Hildenbrand , Ryan Roberts , Nanyong Sun , Yu Zhao , Frank van der Linden , David Rientjes , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org Content-Transfer-Encoding: quoted-printable Message-Id: <2122761A-45AD-4AEC-AE88-B51E92E2CA40@linux.dev> References: <20261003002123.505555-1-jthoughton@google.com> <20261003002123.505555-8-jthoughton@google.com> To: James Houghton X-Mailer: Apple Mail (2.3901.200.71.1.16) X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: D69FF100002 X-Stat-Signature: 7mm7w8m1msjsi7r79gajy7mpeauoe4ze X-Rspam-User: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1794034935-767112 X-HE-Meta: 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 CmMhzdKH iMmMinxyLbjb8pQm5CWBnQ//tHUBSsL446okBvJkCXpptBkRlH45M+1AOEBSPzdQ+Jv1i8cT9nNbX6034QYrbKFAxJh5+hb8z3Vom5QwFPuSgE1akVeVzqoZuvySy1ZZPMQW9omZDSDeqk/p9DCVyQEsvAAdHx5ohPfky9DOZ7nLVVwq5UwstLn1sEodBq7QHBaDgVtjLCxH/g1NcPwwi0clfqyxPNZbFJ5m7iKFwEw87Y6UQI5pe11Opa+PxbbwRvuJcBjjtNJrT17npVH7UkrXAANxWRE/IOVA2/CtNWmbOOuMqOr6Bgn944slx9r/GtRCvMuxp2eoxzno= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 > On Oct 3, 2026, at 08:21, James Houghton = wrote: >=20 > Do not create the vm.hugetlb_optimize_vmemmap sysctl when the > architecture lacks support. This serves only to avoid confusion for > users. >=20 > arm64 support for HVO is conditional on certain hardware features = being > enabled for all online CPUs. By the time hugetlb_vmemmap_init() runs, > all secondary CPUs will have started, and the system feature set will > have stabilized, including HVO-through-BBM, which > arch_hugetlb_vmemmap_optimization_supported() checks for. >=20 > Signed-off-by: James Houghton > --- > mm/hugetlb_vmemmap.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) >=20 > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index 8596a462fee6..817ce39d4cf3 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -763,6 +763,21 @@ static int __init hugetlb_vmemmap_init(void) > /* HUGETLB_VMEMMAP_RESERVE_SIZE should cover all used struct = pages */ > BUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES); >=20 > + /* > + * Architectures that need to probe CPU support for HVO have = done > + * such probing now. = arch_hugetlb_vmemmap_optimization_supported() > + * will return the correct value. > + */ > + if (!arch_hugetlb_vmemmap_optimization_supported()) { I'm wondering if we could put this architectural check into = hugetlb_vmemmap_optimizable(), > + if (vmemmap_optimize_enabled) > + pr_info("vmemmap optimization not supported by = hardware\n"); then, we do not need those code. If the current kernel does not support = HVO, then the sysctl does not exist. It's already a common case when the size = of struct page is not power of two. If users really want to know whether = HVO is enabled, they can check via this sysctl file. Therefore, we don't = need to print a log line. Thanks, Muchun > + /* > + * Return early to avoid setting up the hugetlb vmemmap > + * sysctls; HVO is not usable. > + */ > + return 0; > + } > + > for_each_hstate(h) { > if (hugetlb_vmemmap_optimizable(h)) { > register_sysctl_init("vm", = hugetlb_vmemmap_sysctls); > --=20 > 2.56.0.rc1.315.gc6ed9934b7-goog >=20