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[67.231.145.42]) by mx.google.com with ESMTPS id n123si19087081pgn.151.2019.08.01.11.46.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 01 Aug 2019 11:46:06 -0700 (PDT) Received-SPF: pass (google.com: domain of prvs=3116992784=songliubraving@fb.com designates 67.231.145.42 as permitted sender) client-ip=67.231.145.42; Authentication-Results: mx.google.com; dkim=pass header.i=@fb.com header.s=facebook header.b="MN/0bsf9"; spf=pass (google.com: domain of prvs=3116992784=songliubraving@fb.com designates 67.231.145.42 as permitted sender) smtp.mailfrom="prvs=3116992784=songliubraving@fb.com"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=fb.com Received: from pps.filterd (m0044008.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x71IhIEX002020 for ; Thu, 1 Aug 2019 11:46:05 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=facebook; bh=3of5E40BZCvrFLhVG73nHh78NNgN1wW5I01U6khZ8sM=; b=MN/0bsf9Xlg6LME/eVypAzy3Ytc/TPzqNZU0w6xsPr/OSHiEqVz3cSM6ZcO+7rsYAz7e Jm/UUfTzWpo0g4AnZTsY9jcsEj//O2bD1wdCe3dfhu2Tzu7Tbd/CpPbS46DfLscUZX6u TpcmyUuTdcxrrREd7SYvmp9IPk0962fYXZE= Received: from mail.thefacebook.com (mailout.thefacebook.com [199.201.64.23]) by mx0a-00082601.pphosted.com with ESMTP id 2u430v0qsy-12 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NOT) for ; Thu, 01 Aug 2019 11:46:05 -0700 Received: from mx-out.facebook.com (2620:10d:c081:10::13) by mail.thefacebook.com (2620:10d:c081:35::128) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA) id 15.1.1713.5; Thu, 1 Aug 2019 11:45:53 -0700 Received: by devbig006.ftw2.facebook.com (Postfix, from userid 4523) id 66F6262E1E18; Thu, 1 Aug 2019 11:43:17 -0700 (PDT) Smtp-Origin-Hostprefix: devbig From: Song Liu Smtp-Origin-Hostname: devbig006.ftw2.facebook.com To: , , CC: , , , , , , Song Liu , Johannes Weiner Smtp-Origin-Cluster: ftw2c04 Subject: [PATCH v10 6/7] mm,thp: add read-only THP support for (non-shmem) FS Date: Thu, 1 Aug 2019 11:42:43 -0700 Message-ID: <20190801184244.3169074-7-songliubraving@fb.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190801184244.3169074-1-songliubraving@fb.com> References: <20190801184244.3169074-1-songliubraving@fb.com> X-FB-Internal: Safe MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2019-08-01_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1906280000 definitions=main-1908010194 X-FB-Internal: deliver X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: X-Virus-Scanned: ClamAV using ClamSMTP This patch is (hopefully) the first step to enable THP for non-shmem filesystems. This patch enables an application to put part of its text sections to THP via madvise, for example: madvise((void *)0x600000, 0x200000, MADV_HUGEPAGE); We tried to reuse the logic for THP on tmpfs. Currently, write is not supported for non-shmem THP. khugepaged will only process vma with VM_DENYWRITE. sys_mmap() ignores VM_DENYWRITE requests (see ksys_mmap_pgoff). The only way to create vma with VM_DENYWRITE is execve(). This requirement limits non-shmem THP to text sections. The next patch will handle writes, which would only happen when the all the vmas with VM_DENYWRITE are unmapped. An EXPERIMENTAL config, READ_ONLY_THP_FOR_FS, is added to gate this feature. Cc: Johannes Weiner Acked-by: Rik van Riel Acked-by: Kirill A. Shutemov Signed-off-by: Song Liu Acked-by: Johannes Weiner --- mm/Kconfig | 11 ++++ mm/filemap.c | 4 +- mm/khugepaged.c | 149 ++++++++++++++++++++++++++++++++++-------------- mm/rmap.c | 12 ++-- 4 files changed, 128 insertions(+), 48 deletions(-) diff --git a/mm/Kconfig b/mm/Kconfig index 56cec636a1fc..06f758786e4a 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -723,6 +723,17 @@ config GUP_BENCHMARK config GUP_GET_PTE_LOW_HIGH bool +config READ_ONLY_THP_FOR_FS + bool "Read-only THP for filesystems (EXPERIMENTAL)" + depends on TRANSPARENT_HUGE_PAGECACHE && SHMEM + + help + Allow khugepaged to put read-only file-backed pages in THP. + + This is marked experimental because it is a new feature. Write + support of file THPs will be developed in the next few release + cycles. + config ARCH_HAS_PTE_SPECIAL bool diff --git a/mm/filemap.c b/mm/filemap.c index 97c7b7b92c20..0b8b117dbed6 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -203,8 +203,8 @@ static void unaccount_page_cache_page(struct address_space *mapping, __mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr); if (PageTransHuge(page)) __dec_node_page_state(page, NR_SHMEM_THPS); - } else { - VM_BUG_ON_PAGE(PageTransHuge(page), page); + } else if (PageTransHuge(page)) { + __dec_node_page_state(page, NR_FILE_THPS); } /* diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 9d3cc2061960..8fb26856a7e9 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -48,6 +48,7 @@ enum scan_result { SCAN_CGROUP_CHARGE_FAIL, SCAN_EXCEED_SWAP_PTE, SCAN_TRUNCATED, + SCAN_PAGE_HAS_PRIVATE, }; #define CREATE_TRACE_POINTS @@ -410,7 +411,11 @@ static bool hugepage_vma_check(struct vm_area_struct *vma, (vm_flags & VM_NOHUGEPAGE) || test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags)) return false; - if (shmem_file(vma->vm_file)) { + + if (shmem_file(vma->vm_file) || + (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && + vma->vm_file && + (vm_flags & VM_DENYWRITE))) { if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) return false; return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, @@ -462,8 +467,9 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma, unsigned long hstart, hend; /* - * khugepaged does not yet work on non-shmem files or special - * mappings. And file-private shmem THP is not supported. + * khugepaged only supports read-only files for non-shmem files. + * khugepaged does not yet work on special mappings. And + * file-private shmem THP is not supported. */ if (!hugepage_vma_check(vma, vm_flags)) return 0; @@ -1426,12 +1432,12 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff) } /** - * collapse_file - collapse small tmpfs/shmem pages into huge one. + * collapse_file - collapse filemap/tmpfs/shmem pages into huge one. * * Basic scheme is simple, details are more complex: * - allocate and lock a new huge page; * - scan page cache replacing old pages with the new one - * + swap in pages if necessary; + * + swap/gup in pages if necessary; * + fill in gaps; * + keep old pages around in case rollback is required; * - if replacing succeeds: @@ -1455,7 +1461,9 @@ static void collapse_file(struct mm_struct *mm, LIST_HEAD(pagelist); XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); int nr_none = 0, result = SCAN_SUCCEED; + bool is_shmem = shmem_file(file); + VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem); VM_BUG_ON(start & (HPAGE_PMD_NR - 1)); /* Only allocate from the target node */ @@ -1487,7 +1495,8 @@ static void collapse_file(struct mm_struct *mm, } while (1); __SetPageLocked(new_page); - __SetPageSwapBacked(new_page); + if (is_shmem) + __SetPageSwapBacked(new_page); new_page->index = start; new_page->mapping = mapping; @@ -1502,41 +1511,75 @@ static void collapse_file(struct mm_struct *mm, struct page *page = xas_next(&xas); VM_BUG_ON(index != xas.xa_index); - if (!page) { - /* - * Stop if extent has been truncated or hole-punched, - * and is now completely empty. - */ - if (index == start) { - if (!xas_next_entry(&xas, end - 1)) { - result = SCAN_TRUNCATED; + if (is_shmem) { + if (!page) { + /* + * Stop if extent has been truncated or + * hole-punched, and is now completely + * empty. + */ + if (index == start) { + if (!xas_next_entry(&xas, end - 1)) { + result = SCAN_TRUNCATED; + goto xa_locked; + } + xas_set(&xas, index); + } + if (!shmem_charge(mapping->host, 1)) { + result = SCAN_FAIL; goto xa_locked; } - xas_set(&xas, index); + xas_store(&xas, new_page); + nr_none++; + continue; } - if (!shmem_charge(mapping->host, 1)) { - result = SCAN_FAIL; + + if (xa_is_value(page) || !PageUptodate(page)) { + xas_unlock_irq(&xas); + /* swap in or instantiate fallocated page */ + if (shmem_getpage(mapping->host, index, &page, + SGP_NOHUGE)) { + result = SCAN_FAIL; + goto xa_unlocked; + } + } else if (trylock_page(page)) { + get_page(page); + xas_unlock_irq(&xas); + } else { + result = SCAN_PAGE_LOCK; goto xa_locked; } - xas_store(&xas, new_page); - nr_none++; - continue; - } - - if (xa_is_value(page) || !PageUptodate(page)) { - xas_unlock_irq(&xas); - /* swap in or instantiate fallocated page */ - if (shmem_getpage(mapping->host, index, &page, - SGP_NOHUGE)) { + } else { /* !is_shmem */ + if (!page || xa_is_value(page)) { + xas_unlock_irq(&xas); + page_cache_sync_readahead(mapping, &file->f_ra, + file, index, + PAGE_SIZE); + /* drain pagevecs to help isolate_lru_page() */ + lru_add_drain(); + page = find_lock_page(mapping, index); + if (unlikely(page == NULL)) { + result = SCAN_FAIL; + goto xa_unlocked; + } + } else if (!PageUptodate(page)) { + xas_unlock_irq(&xas); + wait_on_page_locked(page); + if (!trylock_page(page)) { + result = SCAN_PAGE_LOCK; + goto xa_unlocked; + } + get_page(page); + } else if (PageDirty(page)) { result = SCAN_FAIL; - goto xa_unlocked; + goto xa_locked; + } else if (trylock_page(page)) { + get_page(page); + xas_unlock_irq(&xas); + } else { + result = SCAN_PAGE_LOCK; + goto xa_locked; } - } else if (trylock_page(page)) { - get_page(page); - xas_unlock_irq(&xas); - } else { - result = SCAN_PAGE_LOCK; - goto xa_locked; } /* @@ -1565,6 +1608,12 @@ static void collapse_file(struct mm_struct *mm, goto out_unlock; } + if (page_has_private(page) && + !try_to_release_page(page, GFP_KERNEL)) { + result = SCAN_PAGE_HAS_PRIVATE; + break; + } + if (page_mapped(page)) unmap_mapping_pages(mapping, index, 1, false); @@ -1602,12 +1651,18 @@ static void collapse_file(struct mm_struct *mm, goto xa_unlocked; } - __inc_node_page_state(new_page, NR_SHMEM_THPS); + if (is_shmem) + __inc_node_page_state(new_page, NR_SHMEM_THPS); + else + __inc_node_page_state(new_page, NR_FILE_THPS); + if (nr_none) { struct zone *zone = page_zone(new_page); __mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none); - __mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none); + if (is_shmem) + __mod_node_page_state(zone->zone_pgdat, + NR_SHMEM, nr_none); } xa_locked: @@ -1645,10 +1700,15 @@ static void collapse_file(struct mm_struct *mm, SetPageUptodate(new_page); page_ref_add(new_page, HPAGE_PMD_NR - 1); - set_page_dirty(new_page); mem_cgroup_commit_charge(new_page, memcg, false, true); + + if (is_shmem) { + set_page_dirty(new_page); + lru_cache_add_anon(new_page); + } else { + lru_cache_add_file(new_page); + } count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1); - lru_cache_add_anon(new_page); /* * Remove pte page tables, so we can re-fault the page as huge. @@ -1663,7 +1723,9 @@ static void collapse_file(struct mm_struct *mm, /* Something went wrong: roll back page cache changes */ xas_lock_irq(&xas); mapping->nrpages -= nr_none; - shmem_uncharge(mapping->host, nr_none); + + if (is_shmem) + shmem_uncharge(mapping->host, nr_none); xas_set(&xas, start); xas_for_each(&xas, page, end - 1) { @@ -1746,7 +1808,8 @@ static void khugepaged_scan_file(struct mm_struct *mm, break; } - if (page_count(page) != 1 + page_mapcount(page)) { + if (page_count(page) != + 1 + page_mapcount(page) + page_has_private(page)) { result = SCAN_PAGE_COUNT; break; } @@ -1853,11 +1916,13 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages, VM_BUG_ON(khugepaged_scan.address < hstart || khugepaged_scan.address + HPAGE_PMD_SIZE > hend); - if (shmem_file(vma->vm_file)) { + if (vma->vm_file) { struct file *file; pgoff_t pgoff = linear_page_index(vma, khugepaged_scan.address); - if (!shmem_huge_enabled(vma)) + + if (shmem_file(vma->vm_file) + && !shmem_huge_enabled(vma)) goto skip; file = get_file(vma->vm_file); up_read(&mm->mmap_sem); diff --git a/mm/rmap.c b/mm/rmap.c index e5dfe2ae6b0d..87cfa2c19eda 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1192,8 +1192,10 @@ void page_add_file_rmap(struct page *page, bool compound) } if (!atomic_inc_and_test(compound_mapcount_ptr(page))) goto out; - VM_BUG_ON_PAGE(!PageSwapBacked(page), page); - __inc_node_page_state(page, NR_SHMEM_PMDMAPPED); + if (PageSwapBacked(page)) + __inc_node_page_state(page, NR_SHMEM_PMDMAPPED); + else + __inc_node_page_state(page, NR_FILE_PMDMAPPED); } else { if (PageTransCompound(page) && page_mapping(page)) { VM_WARN_ON_ONCE(!PageLocked(page)); @@ -1232,8 +1234,10 @@ static void page_remove_file_rmap(struct page *page, bool compound) } if (!atomic_add_negative(-1, compound_mapcount_ptr(page))) goto out; - VM_BUG_ON_PAGE(!PageSwapBacked(page), page); - __dec_node_page_state(page, NR_SHMEM_PMDMAPPED); + if (PageSwapBacked(page)) + __dec_node_page_state(page, NR_SHMEM_PMDMAPPED); + else + __dec_node_page_state(page, NR_FILE_PMDMAPPED); } else { if (!atomic_add_negative(-1, &page->_mapcount)) goto out;