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 4EE3F215782 for ; Mon, 17 Mar 2025 05:11:41 +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=1742188301; cv=none; b=CQKy1ok0i8yvyr+IwH+W02q8Zw/ByP4kS/uF6R1/+Gtb8uRIMcy10PDcfXOGLlPzQnP16YBOIH6wnKPnzU9zeai93AUuQTjVknEBlQgqHOKe+LOL9vS0GDBCF4QEFPtiHBhWH2S+6skdzHDZi8fhqQFdpxJ8DKld8NVz9hivMWE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742188301; c=relaxed/simple; bh=NYIDVtx07OIJjDi6ITlNQFhj91z5VzzgcFlTufTa3X0=; h=Date:To:From:Subject:Message-Id; b=T7SbAvPVPoUuGVp0h51WsoOHVSXAw48LeV/T/o8c9TknL3XKHsf/+elhxSF4/i69KwDlCZF3x9An9BFvC/7+zlVu/q1eUc+N2gHN0WxPgctrRdG8ITqFxYFvfgfIvBvRthmbL14y1XZAGmS2AtrPJPFMDOGM4qzbBIv1DVMZZW0= 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=Wvxa9hsK; 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="Wvxa9hsK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1C935C4CEEC; Mon, 17 Mar 2025 05:11:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1742188301; bh=NYIDVtx07OIJjDi6ITlNQFhj91z5VzzgcFlTufTa3X0=; h=Date:To:From:Subject:From; b=Wvxa9hsKjJ+UHtT46YtvF3uRKwtF1a7i7+W1TqiS3tjXj6QD7TkQVviUmjm25zYtz bLfdsL7X9isIGx26sgBk7pYl6CFwWa2OIKFHqia2+L+4DSKckJYYMdVn04JEH4HKty jJtmCe3sasYqmeai71XTlCZGM/wlSX+zLum0ZBk8= Date: Sun, 16 Mar 2025 22:11:40 -0700 To: mm-commits@vger.kernel.org,zhengtangquan@oppo.com,yosryahmed@google.com,ying.huang@intel.com,yangyicong@hisilicon.com,will@kernel.org,wangkefeng.wang@huawei.com,tglx@linutronix.de,shahuang@redhat.com,ryan.roberts@arm.com,paul.walmsley@sifive.com,palmer@dabbelt.com,mingo@redhat.com,mfo@canonical.com,mark.rutland@arm.com,lorenzo.stoakes@oracle.com,kirill.shutemov@linux.intel.com,kasong@tencent.com,ioworker0@gmail.com,hpa@zytor.com,gshan@redhat.com,david@redhat.com,dave.hansen@linux.intel.com,chrisl@kernel.org,catalin.marinas@arm.com,bp@alien8.de,baolin.wang@linux.alibaba.com,aou@eecs.berkeley.edu,anshuman.khandual@arm.com,v-songbaohua@oppo.com,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-stable] mm-support-batched-unmap-for-lazyfree-large-folios-during-reclamation.patch removed from -mm tree Message-Id: <20250317051141.1C935C4CEEC@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: support batched unmap for lazyfree large folios during reclamation has been removed from the -mm tree. Its filename was mm-support-batched-unmap-for-lazyfree-large-folios-during-reclamation.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Barry Song Subject: mm: support batched unmap for lazyfree large folios during reclamation Date: Fri, 14 Feb 2025 22:30:14 +1300 Currently, the PTEs and rmap of a large folio are removed one at a time. This is not only slow but also causes the large folio to be unnecessarily added to deferred_split, which can lead to races between the deferred_split shrinker callback and memory reclamation. This patch releases all PTEs and rmap entries in a batch. Currently, it only handles lazyfree large folios. The below microbench tries to reclaim 128MB lazyfree large folios whose sizes are 64KiB: #include #include #include #include #define SIZE 128*1024*1024 // 128 MB unsigned long read_split_deferred() { FILE *file = fopen("/sys/kernel/mm/transparent_hugepage" "/hugepages-64kB/stats/split_deferred", "r"); if (!file) { perror("Error opening file"); return 0; } unsigned long value; if (fscanf(file, "%lu", &value) != 1) { perror("Error reading value"); fclose(file); return 0; } fclose(file); return value; } int main(int argc, char *argv[]) { while(1) { volatile int *p = mmap(0, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); memset((void *)p, 1, SIZE); madvise((void *)p, SIZE, MADV_FREE); clock_t start_time = clock(); unsigned long start_split = read_split_deferred(); madvise((void *)p, SIZE, MADV_PAGEOUT); clock_t end_time = clock(); unsigned long end_split = read_split_deferred(); double elapsed_time = (double)(end_time - start_time) / CLOCKS_PER_SEC; printf("Time taken by reclamation: %f seconds, split_deferred: %ld\n", elapsed_time, end_split - start_split); munmap((void *)p, SIZE); } return 0; } w/o patch: ~ # ./a.out Time taken by reclamation: 0.177418 seconds, split_deferred: 2048 Time taken by reclamation: 0.178348 seconds, split_deferred: 2048 Time taken by reclamation: 0.174525 seconds, split_deferred: 2048 Time taken by reclamation: 0.171620 seconds, split_deferred: 2048 Time taken by reclamation: 0.172241 seconds, split_deferred: 2048 Time taken by reclamation: 0.174003 seconds, split_deferred: 2048 Time taken by reclamation: 0.171058 seconds, split_deferred: 2048 Time taken by reclamation: 0.171993 seconds, split_deferred: 2048 Time taken by reclamation: 0.169829 seconds, split_deferred: 2048 Time taken by reclamation: 0.172895 seconds, split_deferred: 2048 Time taken by reclamation: 0.176063 seconds, split_deferred: 2048 Time taken by reclamation: 0.172568 seconds, split_deferred: 2048 Time taken by reclamation: 0.171185 seconds, split_deferred: 2048 Time taken by reclamation: 0.170632 seconds, split_deferred: 2048 Time taken by reclamation: 0.170208 seconds, split_deferred: 2048 Time taken by reclamation: 0.174192 seconds, split_deferred: 2048 ... w/ patch: ~ # ./a.out Time taken by reclamation: 0.074231 seconds, split_deferred: 0 Time taken by reclamation: 0.071026 seconds, split_deferred: 0 Time taken by reclamation: 0.072029 seconds, split_deferred: 0 Time taken by reclamation: 0.071873 seconds, split_deferred: 0 Time taken by reclamation: 0.073573 seconds, split_deferred: 0 Time taken by reclamation: 0.071906 seconds, split_deferred: 0 Time taken by reclamation: 0.073604 seconds, split_deferred: 0 Time taken by reclamation: 0.075903 seconds, split_deferred: 0 Time taken by reclamation: 0.073191 seconds, split_deferred: 0 Time taken by reclamation: 0.071228 seconds, split_deferred: 0 Time taken by reclamation: 0.071391 seconds, split_deferred: 0 Time taken by reclamation: 0.071468 seconds, split_deferred: 0 Time taken by reclamation: 0.071896 seconds, split_deferred: 0 Time taken by reclamation: 0.072508 seconds, split_deferred: 0 Time taken by reclamation: 0.071884 seconds, split_deferred: 0 Time taken by reclamation: 0.072433 seconds, split_deferred: 0 Time taken by reclamation: 0.071939 seconds, split_deferred: 0 ... Link: https://lkml.kernel.org/r/20250214093015.51024-4-21cnbao@gmail.com Signed-off-by: Barry Song Cc: Albert Ou Cc: Anshuman Khandual Cc: Baolin Wang Cc: Borislav Petkov Cc: Catalin Marinas Cc: Chis Li Cc: Dave Hansen Cc: David Hildenbrand Cc: Gavin Shan Cc: "H. Peter Anvin" Cc: "Huang, Ying" Cc: Ingo Molnar Cc: Kairui Song Cc: Kefeng Wang Cc: "Kirill A. Shutemov" Cc: Lance Yang Cc: Lorenzo Stoakes Cc: Mark Rutland Cc: Mauricio Faria de Oliveira Cc: Palmer Dabbelt Cc: Paul Walmsley Cc: Ryan Roberts Cc: Shaoqin Huang Cc: Tangquan Zheng Cc: Thomas Gleixner Cc: Will Deacon Cc: Yicong Yang Cc: Yosry Ahmed Signed-off-by: Andrew Morton --- mm/rmap.c | 72 ++++++++++++++++++++++++++++++++++++---------------- 1 file changed, 50 insertions(+), 22 deletions(-) --- a/mm/rmap.c~mm-support-batched-unmap-for-lazyfree-large-folios-during-reclamation +++ a/mm/rmap.c @@ -1722,6 +1722,25 @@ void folio_remove_rmap_pmd(struct folio #endif } +/* We support batch unmapping of PTEs for lazyfree large folios */ +static inline bool can_batch_unmap_folio_ptes(unsigned long addr, + struct folio *folio, pte_t *ptep) +{ + const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY; + int max_nr = folio_nr_pages(folio); + pte_t pte = ptep_get(ptep); + + if (!folio_test_anon(folio) || folio_test_swapbacked(folio)) + return false; + if (pte_unused(pte)) + return false; + if (pte_pfn(pte) != folio_pfn(folio)) + return false; + + return folio_pte_batch(folio, addr, ptep, pte, max_nr, fpb_flags, NULL, + NULL, NULL) == max_nr; +} + /* * @arg: enum ttu_flags will be passed to this argument */ @@ -1735,6 +1754,7 @@ static bool try_to_unmap_one(struct foli struct page *subpage; struct mmu_notifier_range range; enum ttu_flags flags = (enum ttu_flags)(long)arg; + unsigned long nr_pages = 1, end_addr; unsigned long pfn; unsigned long hsz = 0; @@ -1874,23 +1894,26 @@ static bool try_to_unmap_one(struct foli if (pte_dirty(pteval)) folio_mark_dirty(folio); } else if (likely(pte_present(pteval))) { - flush_cache_page(vma, address, pfn); - /* Nuke the page table entry. */ - if (should_defer_flush(mm, flags)) { - /* - * We clear the PTE but do not flush so potentially - * a remote CPU could still be writing to the folio. - * If the entry was previously clean then the - * architecture must guarantee that a clear->dirty - * transition on a cached TLB entry is written through - * and traps if the PTE is unmapped. - */ - pteval = ptep_get_and_clear(mm, address, pvmw.pte); + if (folio_test_large(folio) && !(flags & TTU_HWPOISON) && + can_batch_unmap_folio_ptes(address, folio, pvmw.pte)) + nr_pages = folio_nr_pages(folio); + end_addr = address + nr_pages * PAGE_SIZE; + flush_cache_range(vma, address, end_addr); - set_tlb_ubc_flush_pending(mm, pteval, address, address + PAGE_SIZE); - } else { - pteval = ptep_clear_flush(vma, address, pvmw.pte); - } + /* Nuke the page table entry. */ + pteval = get_and_clear_full_ptes(mm, address, pvmw.pte, nr_pages, 0); + /* + * We clear the PTE but do not flush so potentially + * a remote CPU could still be writing to the folio. + * If the entry was previously clean then the + * architecture must guarantee that a clear->dirty + * transition on a cached TLB entry is written through + * and traps if the PTE is unmapped. + */ + if (should_defer_flush(mm, flags)) + set_tlb_ubc_flush_pending(mm, pteval, address, end_addr); + else + flush_tlb_range(vma, address, end_addr); if (pte_dirty(pteval)) folio_mark_dirty(folio); } else { @@ -1968,7 +1991,7 @@ static bool try_to_unmap_one(struct foli * redirtied either using the page table or a previously * obtained GUP reference. */ - set_pte_at(mm, address, pvmw.pte, pteval); + set_ptes(mm, address, pvmw.pte, pteval, nr_pages); folio_set_swapbacked(folio); goto walk_abort; } else if (ref_count != 1 + map_count) { @@ -1981,10 +2004,10 @@ static bool try_to_unmap_one(struct foli * We'll come back here later and detect if the folio was * dirtied when the additional reference is gone. */ - set_pte_at(mm, address, pvmw.pte, pteval); + set_ptes(mm, address, pvmw.pte, pteval, nr_pages); goto walk_abort; } - dec_mm_counter(mm, MM_ANONPAGES); + add_mm_counter(mm, MM_ANONPAGES, -nr_pages); goto discard; } @@ -2049,13 +2072,18 @@ static bool try_to_unmap_one(struct foli dec_mm_counter(mm, mm_counter_file(folio)); } discard: - if (unlikely(folio_test_hugetlb(folio))) + if (unlikely(folio_test_hugetlb(folio))) { hugetlb_remove_rmap(folio); - else - folio_remove_rmap_pte(folio, subpage, vma); + } else { + folio_remove_rmap_ptes(folio, subpage, nr_pages, vma); + folio_ref_sub(folio, nr_pages - 1); + } if (vma->vm_flags & VM_LOCKED) mlock_drain_local(); folio_put(folio); + /* We have already batched the entire folio */ + if (nr_pages > 1) + goto walk_done; continue; walk_abort: ret = false; _ Patches currently in -mm which might be from v-songbaohua@oppo.com are