From nobody Sun Feb 8 12:36:55 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 953B9210F59 for ; Tue, 29 Apr 2025 05:24:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745904254; cv=none; b=rnnNawUHX9pqFvuoRYxuKE0cJ61a+lyCnj7aWJgumLBYU9OwnyYp9qkexZ01zIsGCFCpYsM/uVvTj8gJX3GNfmyxSgJMTA8gcZccC9BcyzIvJPf+bsjG6J62pcX770q3LGoxsufvlT5jshO2bubfU2z6tjYnUC9Q1ZXmTPK8atA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1745904254; c=relaxed/simple; bh=yC8EkzjfJnpRtwbK8PCtq1kwykP5W1Rc6CSHuPNLLOc=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=rwg50v5bSLAyPRXkmNfmIuCREvJLjrlNWY+E40lujjFkmn1YBgg6PPmaeSCODisbzugllRF8YkSaQwOqNR4ySTneIcDZdIrYXOLfiqGelgtK5v7Kt0nSTBdTSK776srGRTSa6ydIKvPymsRaRBkQk9J+BBafgewIem7G52DYtP0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 12E031515; Mon, 28 Apr 2025 22:24:05 -0700 (PDT) Received: from K4MQJ0H1H2.arm.com (unknown [10.163.78.253]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 98F553F5A1; Mon, 28 Apr 2025 22:24:02 -0700 (PDT) From: Dev Jain To: akpm@linux-foundation.org Cc: ryan.roberts@arm.com, david@redhat.com, willy@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, catalin.marinas@arm.com, will@kernel.org, Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, vbabka@suse.cz, jannh@google.com, anshuman.khandual@arm.com, peterx@redhat.com, joey.gouly@arm.com, ioworker0@gmail.com, baohua@kernel.org, kevin.brodsky@arm.com, quic_zhenhuah@quicinc.com, christophe.leroy@csgroup.eu, yangyicong@hisilicon.com, linux-arm-kernel@lists.infradead.org, namit@vmware.com, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com, Dev Jain Subject: [PATCH v2 2/7] mm: Optimize mprotect() by batch-skipping PTEs Date: Tue, 29 Apr 2025 10:53:31 +0530 Message-Id: <20250429052336.18912-3-dev.jain@arm.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20250429052336.18912-1-dev.jain@arm.com> References: <20250429052336.18912-1-dev.jain@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" In case of prot_numa, there are various cases in which we can skip to the next iteration. Since the skip condition is based on the folio and not the PTEs, we can skip a PTE batch. Signed-off-by: Dev Jain --- mm/mprotect.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 70f59aa8c2a8..ec5d17af7650 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -91,6 +91,9 @@ static bool prot_numa_skip(struct vm_area_struct *vma, st= ruct folio *folio, bool toptier; int nid; =20 + if (folio_is_zone_device(folio) || folio_test_ksm(folio)) + return true; + /* Also skip shared copy-on-write pages */ if (is_cow_mapping(vma->vm_flags) && (folio_maybe_dma_pinned(folio) || @@ -126,8 +129,10 @@ static bool prot_numa_skip(struct vm_area_struct *vma,= struct folio *folio, } =20 static bool prot_numa_avoid_fault(struct vm_area_struct *vma, - unsigned long addr, pte_t oldpte, int target_node) + unsigned long addr, pte_t *pte, pte_t oldpte, int target_node, + int max_nr, int *nr) { + const fpb_t flags =3D FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; struct folio *folio; int ret; =20 @@ -136,12 +141,16 @@ static bool prot_numa_avoid_fault(struct vm_area_stru= ct *vma, return true; =20 folio =3D vm_normal_folio(vma, addr, oldpte); - if (!folio || folio_is_zone_device(folio) || - folio_test_ksm(folio)) + if (!folio) return true; + ret =3D prot_numa_skip(vma, folio, target_node); - if (ret) + if (ret) { + if (folio_test_large(folio) && max_nr !=3D 1) + *nr =3D folio_pte_batch(folio, addr, pte, oldpte, + max_nr, flags, NULL, NULL, NULL); return ret; + } if (folio_use_access_time(folio)) folio_xchg_access_time(folio, jiffies_to_msecs(jiffies)); @@ -159,6 +168,7 @@ static long change_pte_range(struct mmu_gather *tlb, bool prot_numa =3D cp_flags & MM_CP_PROT_NUMA; bool uffd_wp =3D cp_flags & MM_CP_UFFD_WP; bool uffd_wp_resolve =3D cp_flags & MM_CP_UFFD_WP_RESOLVE; + int nr; =20 tlb_change_page_size(tlb, PAGE_SIZE); pte =3D pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); @@ -173,8 +183,10 @@ static long change_pte_range(struct mmu_gather *tlb, flush_tlb_batched_pending(vma->vm_mm); arch_enter_lazy_mmu_mode(); do { + nr =3D 1; oldpte =3D ptep_get(pte); if (pte_present(oldpte)) { + int max_nr =3D (end - addr) >> PAGE_SHIFT; pte_t ptent; =20 /* @@ -182,8 +194,9 @@ static long change_pte_range(struct mmu_gather *tlb, * pages. See similar comment in change_huge_pmd. */ if (prot_numa && - prot_numa_avoid_fault(vma, addr, - oldpte, target_node)) + prot_numa_avoid_fault(vma, addr, pte, + oldpte, target_node, + max_nr, &nr)) continue; =20 oldpte =3D ptep_modify_prot_start(vma, addr, pte); @@ -300,7 +313,7 @@ static long change_pte_range(struct mmu_gather *tlb, pages++; } } - } while (pte++, addr +=3D PAGE_SIZE, addr !=3D end); + } while (pte +=3D nr, addr +=3D nr * PAGE_SIZE, addr !=3D end); arch_leave_lazy_mmu_mode(); pte_unmap_unlock(pte - 1, ptl); =20 --=20 2.30.2