From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0E5F7606A32C for ; Sat, 7 Nov 2026 06:45:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=mmcaoCq8; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=PLiMgy2m DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:To:References:Message-Id: Content-Transfer-Encoding:Cc:Date:In-Reply-To:From:Subject:Mime-Version: Content-Type:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=p0Q+aPh9FXmspSlImRXpx816BsnlvW0umQZjVoRPYEU=; b=mmcaoCq8foiBi7 KpZRApOCFFtNH3LJ33B6QemGAIUFNs4xY2QWMZvY/ecMFfL6lHdwlWEhL/qefLuTx6rHA1WokTgRy xMrioFGDhX26tB3oJaps4mCrC4Uct6xoZoblBMmjietdiGRkBz/PcDHBJAsTxcQ1pxabW0xQcHJTN kYBDdcI3RqBGtVLs/nqFi2JFETyq0mcopHMO++0ERaiucjfBFO0ILVtGibVUkbEIUpO3Dk4IUuYQn GPRqZDxVSR+XfcfnNbyyzoTdcPMHIAeoI6HqAVugmmksxWtpGVejWt47eqlPBd2rtY+IhvuCpbJ+M DUuGdEEVZa4q5odBkeLQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xPaBH-0000000EHhH-2ux2; Sat, 07 Nov 2026 06:45:39 +0000 Received: from out-156.mta0.migadu.com ([2001:41d0:1004:224b::9c] helo=mta0.migadu.com) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xPaBC-0000000EHgn-2RGr for linux-arm-kernel@lists.infradead.org; Sat, 07 Nov 2026 06:45:35 +0000 X-Envelope-To: linux-arm-kernel@lists.infradead.org DKIM-Signature: a=rsa-sha256; bh=l8FwMw+tmHQ7yeBnzjT9XdJgKx4elexMVrnBE3P9GII=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794033932; v=1; x=1794638732; b=PLiMgy2mkCsCeBwAzcCbel54H98GbsWHqYUPAwA5TRiOgHIetnjEEAApj6O5kb7uV3oKEhxR LGsMaFY4sLqQldb0T6GTheqink0+up+b5DfPjNWpu057NaTIe9xJfNGONa4kUuFMRghIbI0vCPD uLnvROtZzHXdMzbJHO5d1TDk= X-Envelope-To: linux-arm-kernel@lists.infradead.org Received: by mta10.migadu.com with ESMTPS id c05da5992c7d8cdf; Sat, 07 Nov 2026 06:45:29 +0000 X-Mizu-Trace-ID: c05da5992c7d8cdf 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 13/20] arm64: Support hugetlb vmemmap optimization From: Muchun Song In-Reply-To: <20261003002123.505555-14-jthoughton@google.com> Date: Sat, 7 Nov 2026 14:45:11 +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: References: <20261003002123.505555-1-jthoughton@google.com> <20261003002123.505555-14-jthoughton@google.com> To: James Houghton X-Mailer: Apple Mail (2.3901.200.71.1.16) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261106_224534_766831_80977E00 X-CRM114-Status: GOOD ( 19.84 ) X-Spam-Score: -2.1 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=4.0.1 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 > Support HVO if HW AF and BBML3 are supported. These are the required > features for the vmemmap to be modified in place. >=20 > On arm64 systems that do not have the required hardware features to > support HVO, the HVO sysctl will not appear, and any attempts to = enable > HVO (either via the command line or via > CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON=3Dy) will have no = effect. >=20 > Signed-off-by: James Houghton > --- > arch/arm64/Kconfig | 2 ++ > arch/arm64/include/asm/hugetlb.h | 7 +++++++ > mm/hugetlb_vmemmap.c | 4 ++++ > 3 files changed, 13 insertions(+) >=20 > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index b51d23a62c92..e4c87487bc7f 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -92,7 +92,9 @@ config ARM64 > select ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT > select ARCH_WANT_FRAME_POINTERS > select ARCH_WANT_HUGE_PMD_SHARE if ARM64_4K_PAGES || = (ARM64_16K_PAGES && !ARM64_VA_BITS_36) > + select ARCH_WANT_HUGETLB_VMEMMAP_RO_AFTER_INIT > select ARCH_WANT_LD_ORPHAN_WARN > + select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if ARM64_HW_AFDBM Because vmemmap optimization depends on compound_info_has_mask(), before enabling HVO on arm64, its vmemmap start address needs to be aligned to MAX_FOLIO_VMEMMAP_ALIGN. Therefore, a prerequisite patch is required. Thanks, Muchun > select ARCH_WANTS_EXECMEM_LATE > select ARCH_WANTS_NO_INSTR > select ARCH_WANTS_THP_SWAP if ARM64_4K_PAGES > diff --git a/arch/arm64/include/asm/hugetlb.h = b/arch/arm64/include/asm/hugetlb.h > index d038ff14d16c..938d7896a31e 100644 > --- a/arch/arm64/include/asm/hugetlb.h > +++ b/arch/arm64/include/asm/hugetlb.h > @@ -11,6 +11,7 @@ > #define __ASM_HUGETLB_H >=20 > #include > +#include > #include > #include >=20 > @@ -65,6 +66,12 @@ extern void huge_ptep_modify_prot_commit(struct = vm_area_struct *vma, > unsigned long addr, pte_t = *ptep, > pte_t old_pte, pte_t new_pte); >=20 > +#define __HAVE_ARCH_HVO_SUPPORTED > +static inline bool arch_hugetlb_vmemmap_optimization_supported(void) > +{ > + return system_supports_bbm_through_af(); > +} > + > #include >=20 > static inline void __flush_hugetlb_tlb_range(struct vm_area_struct = *vma, > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index c1c736dd08b9..fabf2b25fe59 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -85,6 +85,10 @@ static int vmemmap_split_pmd(pmd_t *pmd, struct = page *head, unsigned long start, >=20 > /* Make pte visible before pmd. See comment in = pmd_install(). */ > smp_wmb(); > + /* > + * On arm64, this requires BBML3. Its support has = already been > + * checked. > + */ > pmd_populate_kernel(&init_mm, pmd, pgtable); > if (!(walk->flags & VMEMMAP_SPLIT_NO_TLB_FLUSH)) > flush_tlb_kernel_range(start, start + PMD_SIZE); > --=20 > 2.56.0.rc1.315.gc6ed9934b7-goog >=20