From nobody Mon Dec 15 14:45:30 2025 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 0F361257ACF for ; Mon, 19 May 2025 07:48:48 +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=1747640930; cv=none; b=U4Ow2uLRnS+Yvb5Ipzb30DCH5JcPhkjAvsD6TF9tMC0yB+tJQEg92Hkr4yAkTvU3QHaz+gJURBLmFnBg1SdjOXd2sHrMkxMbSnBuf6pXM7mjjnSJa1zYGG9qgv1bC78P3ti75ZVTV+oD0KkT36pRDKjsjY6LyehtA0YcLwJ9tug= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747640930; c=relaxed/simple; bh=P+7mA+e0mNdPIFNh9dUQuRv6rqP2ptUkjxEq2xLIjgA=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Xg/+cjwqCKvtm0xX8HLaX9kCjOii/pDBE+pYO/j1g6WYwFVQMfw7DyvTT8lxsE7DSt4OQkbxQszwhhKVBg5xe0SIV5zvOcBD2gghtgCQqZBY6a/RRhYZ/7pRRkrSgQ0sQ/RB3QvPSIgFqaVz9Lu6AqJlByy5/dlXifBv6R1KeA0= 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 5444B168F; Mon, 19 May 2025 00:48:35 -0700 (PDT) Received: from K4MQJ0H1H2.blr.arm.com (unknown [10.164.18.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 9E5D03F6A8; Mon, 19 May 2025 00:48:41 -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, hughd@google.com, yang@os.amperecomputing.com, ziy@nvidia.com, Dev Jain Subject: [PATCH v3 1/5] mm: Optimize mprotect() by batch-skipping PTEs Date: Mon, 19 May 2025 13:18:20 +0530 Message-Id: <20250519074824.42909-2-dev.jain@arm.com> X-Mailer: git-send-email 2.39.3 (Apple Git-146) In-Reply-To: <20250519074824.42909-1-dev.jain@arm.com> References: <20250519074824.42909-1-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 Reviewed-by: Ryan Roberts --- mm/mprotect.c | 36 +++++++++++++++++++++++++++++------- 1 file changed, 29 insertions(+), 7 deletions(-) diff --git a/mm/mprotect.c b/mm/mprotect.c index 88608d0dc2c2..1ee160ed0b14 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -83,6 +83,18 @@ bool can_change_pte_writable(struct vm_area_struct *vma,= unsigned long addr, return pte_dirty(pte); } =20 +static int mprotect_batch(struct folio *folio, unsigned long addr, pte_t *= ptep, + pte_t pte, int max_nr_ptes) +{ + const fpb_t flags =3D FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; + + if (!folio_test_large(folio) || (max_nr_ptes =3D=3D 1)) + return 1; + + return folio_pte_batch(folio, addr, ptep, pte, max_nr_ptes, flags, + NULL, NULL, NULL); +} + static long change_pte_range(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, pgprot_t newprot, unsigned long cp_flags) @@ -94,6 +106,7 @@ 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_ptes; =20 tlb_change_page_size(tlb, PAGE_SIZE); pte =3D pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); @@ -108,8 +121,10 @@ static long change_pte_range(struct mmu_gather *tlb, flush_tlb_batched_pending(vma->vm_mm); arch_enter_lazy_mmu_mode(); do { + nr_ptes =3D 1; oldpte =3D ptep_get(pte); if (pte_present(oldpte)) { + int max_nr_ptes =3D (end - addr) >> PAGE_SHIFT; pte_t ptent; =20 /* @@ -126,15 +141,18 @@ static long change_pte_range(struct mmu_gather *tlb, continue; =20 folio =3D vm_normal_folio(vma, addr, oldpte); - if (!folio || folio_is_zone_device(folio) || - folio_test_ksm(folio)) + if (!folio) continue; =20 + if (folio_is_zone_device(folio) || + folio_test_ksm(folio)) + goto skip_batch; + /* Also skip shared copy-on-write pages */ if (is_cow_mapping(vma->vm_flags) && (folio_maybe_dma_pinned(folio) || folio_maybe_mapped_shared(folio))) - continue; + goto skip_batch; =20 /* * While migration can move some dirty pages, @@ -143,7 +161,7 @@ static long change_pte_range(struct mmu_gather *tlb, */ if (folio_is_file_lru(folio) && folio_test_dirty(folio)) - continue; + goto skip_batch; =20 /* * Don't mess with PTEs if page is already on the node @@ -151,7 +169,7 @@ static long change_pte_range(struct mmu_gather *tlb, */ nid =3D folio_nid(folio); if (target_node =3D=3D nid) - continue; + goto skip_batch; toptier =3D node_is_toptier(nid); =20 /* @@ -159,8 +177,12 @@ static long change_pte_range(struct mmu_gather *tlb, * balancing is disabled */ if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && - toptier) + toptier) { +skip_batch: + nr_ptes =3D mprotect_batch(folio, addr, pte, + oldpte, max_nr_ptes); continue; + } if (folio_use_access_time(folio)) folio_xchg_access_time(folio, jiffies_to_msecs(jiffies)); @@ -280,7 +302,7 @@ static long change_pte_range(struct mmu_gather *tlb, pages++; } } - } while (pte++, addr +=3D PAGE_SIZE, addr !=3D end); + } while (pte +=3D nr_ptes, addr +=3D nr_ptes * PAGE_SIZE, addr !=3D end); arch_leave_lazy_mmu_mode(); pte_unmap_unlock(pte - 1, ptl); =20 --=20 2.30.2