From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EA389A95C for ; Tue, 22 Jul 2025 20:48:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753217325; cv=none; b=d7s+3jd3Xkj64XEufXs7cttWm156aVpoSh+tT2ypkosIlrMN/gmFIRUFeYe9KOnchBrqg3pymtmuc9rY53ZNNKQ0+O0CkK1m0+MwtgyNfIn5UTUdaWeG/7t38SBHDA9Cv+f3jIdrSoapG/tSTVP6LMK+WURBzmaSpVPWsqtNJ7U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753217325; c=relaxed/simple; bh=4MXMd9D/U94p5mcYwp8MLl6CP02ecgcsorSugAzPKS0=; h=Date:To:From:Subject:Message-Id; b=MI4h8r+/rG47BJFGFwuOzmolIzOtTOfDGZav1y4YzfOGb0XIFzGRe0INcH9vpXae9OGZ3zp3dhhvMlbnc0QMJgMfyUviIjaE8p/KAzs6SrpO5UQXRSA1GE/gxjyogr3uJJSx0T8tBJvQ8Pl1yqtycH7p4dghGGXCZs7csVEmEag= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=fR3qoq7g; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="fR3qoq7g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 58BD4C4CEEB; Tue, 22 Jul 2025 20:48:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1753217324; bh=4MXMd9D/U94p5mcYwp8MLl6CP02ecgcsorSugAzPKS0=; h=Date:To:From:Subject:From; b=fR3qoq7glWhD0HuvkL6LAkJurvWrQi3IS0EMaM+i3CYCa3Mr47li3vU9wrPN+nAHU NgmVqAkPn9P76MxNMs9VtRyzitZcWrGy+QE90i6+YX1Fbvxe+RZT/abStzaB3M3D5g whxfjqJ7jZ3py1MD1LtRDsOkOGxzoGgvaqMnQMp4= Date: Tue, 22 Jul 2025 13:48:43 -0700 To: mm-commits@vger.kernel.org,ziy@nvidia.com,ryan.roberts@arm.com,npache@redhat.com,lorenzo.stoakes@oracle.com,liam.howlett@oracle.com,david@redhat.com,baolin.wang@linux.alibaba.com,baohua@kernel.org,dev.jain@arm.com,akpm@linux-foundation.org From: Andrew Morton Subject: + khugepaged-optimize-__collapse_huge_page_copy_succeeded-by-pte-batching.patch added to mm-new branch Message-Id: <20250722204844.58BD4C4CEEB@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: khugepaged: optimize __collapse_huge_page_copy_succeeded() by PTE batching has been added to the -mm mm-new branch. Its filename is khugepaged-optimize-__collapse_huge_page_copy_succeeded-by-pte-batching.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/khugepaged-optimize-__collapse_huge_page_copy_succeeded-by-pte-batching.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Dev Jain Subject: khugepaged: optimize __collapse_huge_page_copy_succeeded() by PTE batching Date: Tue, 22 Jul 2025 20:35:58 +0530 Use PTE batching to optimize __collapse_huge_page_copy_succeeded(). On arm64, suppose khugepaged is scanning a pte-mapped 2MB THP for collapse. Then, calling ptep_clear() for every pte will cause a TLB flush for every contpte block. Instead, clear_ptes() does a contpte_try_unfold_partial() which will flush the TLB only for the (if any) starting and ending contpte block, if they partially overlap with the range khugepaged is looking at. For all arches, there should be a benefit due to batching atomic operations on mapcounts due to folio_remove_rmap_ptes() and saving some calls. Link: https://lkml.kernel.org/r/20250722150559.96465-3-dev.jain@arm.com Signed-off-by: Dev Jain Acked-by: David Hildenbrand Cc: Baolin Wang Cc: Barry Song Cc: Liam Howlett Cc: Lorenzo Stoakes Cc: Mariano Pache Cc: Ryan Roberts Cc: Zi Yan Signed-off-by: Andrew Morton --- mm/khugepaged.c | 25 ++++++++++++++++++------- 1 file changed, 18 insertions(+), 7 deletions(-) --- a/mm/khugepaged.c~khugepaged-optimize-__collapse_huge_page_copy_succeeded-by-pte-batching +++ a/mm/khugepaged.c @@ -700,12 +700,15 @@ static void __collapse_huge_page_copy_su spinlock_t *ptl, struct list_head *compound_pagelist) { + unsigned long end = address + HPAGE_PMD_SIZE; struct folio *src, *tmp; - pte_t *_pte; pte_t pteval; + pte_t *_pte; + int nr_ptes; - for (_pte = pte; _pte < pte + HPAGE_PMD_NR; - _pte++, address += PAGE_SIZE) { + for (_pte = pte; _pte < pte + HPAGE_PMD_NR; _pte += nr_ptes, + address += nr_ptes * PAGE_SIZE) { + nr_ptes = 1; pteval = ptep_get(_pte); if (pte_none(pteval) || is_zero_pfn(pte_pfn(pteval))) { add_mm_counter(vma->vm_mm, MM_ANONPAGES, 1); @@ -722,18 +725,26 @@ static void __collapse_huge_page_copy_su struct page *src_page = pte_page(pteval); src = page_folio(src_page); - if (!folio_test_large(src)) + + if (folio_test_large(src)) { + int max_nr_ptes = (end - address) >> PAGE_SHIFT; + + nr_ptes = folio_pte_batch(src, _pte, pteval, max_nr_ptes); + } else { release_pte_folio(src); + } + /* * ptl mostly unnecessary, but preempt has to * be disabled to update the per-cpu stats * inside folio_remove_rmap_pte(). */ spin_lock(ptl); - ptep_clear(vma->vm_mm, address, _pte); - folio_remove_rmap_pte(src, src_page, vma); + clear_ptes(vma->vm_mm, address, _pte, nr_ptes); + folio_remove_rmap_ptes(src, src_page, nr_ptes, vma); spin_unlock(ptl); - free_folio_and_swap_cache(src); + free_swap_cache(src); + folio_put_refs(src, nr_ptes); } } _ Patches currently in -mm which might be from dev.jain@arm.com are mm-refactor-mm_cp_prot_numa-skipping-case-into-new-function.patch mm-optimize-mprotect-for-mm_cp_prot_numa-by-batch-skipping-ptes.patch mm-add-batched-versions-of-ptep_modify_prot_start-commit.patch mm-introduce-fpb_respect_write-for-pte-batching-infrastructure.patch mm-split-can_change_pte_writable-into-private-and-shared-parts.patch mm-optimize-mprotect-by-pte-batching.patch arm64-add-batched-versions-of-ptep_modify_prot_start-commit.patch khugepaged-optimize-__collapse_huge_page_copy_succeeded-by-pte-batching.patch khugepaged-optimize-collapse_pte_mapped_thp-by-pte-batching.patch