Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752999AbcDPAd3 (ORCPT ); Fri, 15 Apr 2016 20:33:29 -0400 Received: from mga03.intel.com ([134.134.136.65]:61878 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752397AbcDPAYO (ORCPT ); Fri, 15 Apr 2016 20:24:14 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,489,1455004800"; d="scan'208";a="956047278" From: "Kirill A. Shutemov" To: Hugh Dickins , Andrea Arcangeli , Andrew Morton Cc: Dave Hansen , Vlastimil Babka , Christoph Lameter , Naoya Horiguchi , Jerome Marchand , Yang Shi , Sasha Levin , Andres Lagar-Cavilla , Ning Qu , linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv7 00/29] THP-enabled tmpfs/shmem using compound pages Date: Sat, 16 Apr 2016 03:23:31 +0300 Message-Id: <1460766240-84565-1-git-send-email-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.8.0.rc3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9854 Lines: 251 This is probably the last update before the mm summit. Main forcus is on khugepaged stability. khugepaged is in more reasonable shape now. I missed quite a few corner cases on first try. I run this version via LTP, trinity and syzkaller without crashes so far. The patchset is on top of v4.6-rc3 plus Hugh's "easy preliminaries to THPagecache" and Ebru's khugepaged swapin patches form -mm tree. Git tree: git://git.kernel.org/pub/scm/linux/kernel/git/kas/linux.git hugetmpfs/v7 == Changelog == v7: - khugepaged updates: + fix page leak/page cache corruption on collapse fail; + filter out VMAs not suitable for huge pages due misaligned vm_pgoff; + fix build without CONFIG_SHMEM; + drop few over-protective checks; - fix bogus VM_BUG_ON() in __delete_from_page_cache(); v6: - experimental collapse support; - fix swapout mapped huge pages; - fix page leak in faularound code; - fix exessive huge page allocation with huge=within_size; - rename VM_NO_THP to VM_NO_KHUGEPAGED; - fix condition in hugepage_madvise(); - accounting reworked again; v5: - add FileHugeMapped to /proc/PID/smaps; - make FileHugeMapped in meminfo aligned with other fields; - Documentation/vm/transhuge.txt updated; v4: - first four patch were applied to -mm tree; - drop pages beyond i_size on split_huge_pages; - few small random bugfixes; v3: - huge= mountoption now can have values always, within_size, advice and never; - sysctl handle is replaced with sysfs knob; - MADV_HUGEPAGE/MADV_NOHUGEPAGE is now respected on page allocation via page fault; - mlock() handling had been fixed; - bunch of smaller bugfixes and cleanups. == Design overview == Huge pages are allocated by shmem when it's allowed (by mount option) and there's no entries for the range in radix-tree. Huge page is represented by HPAGE_PMD_NR entries in radix-tree. MM core maps a page with PMD if ->fault() returns huge page and the VMA is suitable for huge pages (size, alignment). There's no need into two requests to file system: filesystem returns huge page if it can, graceful fallback to small pages otherwise. As with DAX, split_huge_pmd() is implemented by unmapping the PMD: we can re-fault the page with PTEs later. Basic scheme for split_huge_page() is the same as for anon-THP. Few differences: - File pages are on radix-tree, so we have head->_count offset by HPAGE_PMD_NR. The count got distributed to small pages during split. - mapping->tree_lock prevents non-lockless access to pages under split over radix-tree; - Lockless access is prevented by setting the head->_count to 0 during split, so get_page_unless_zero() would fail; - After split, some pages can be beyond i_size. We drop them from radix-tree. - We don't setup migration entries. Just unmap pages. It helps handling cases when i_size is in the middle of the page: no need handle unmap pages beyond i_size manually. COW mapping handled on PTE-level. It's not clear how beneficial would be allocation of huge pages on COW faults. And it would require some code to make them work. I think at some point we can consider teaching khugepaged to collapse pages in COW mappings, but allocating huge on fault is probably overkill. As with anon THP, we mlock file huge page only if it mapped with PMD. PTE-mapped THPs are never mlocked. This way we can avoid all sorts of scenarios when we can leak mlocked page. As with anon THP, we split huge page on swap out. Truncate and punch hole that only cover part of THP range is implemented by zero out this part of THP. This have visible effect on fallocate(FALLOC_FL_PUNCH_HOLE) behaviour. As we don't really create hole in this case, lseek(SEEK_HOLE) may have inconsistent results depending what pages happened to be allocated. I don't think this will be a problem. == Patchset overview == [01/29] Update documentation on THP vs. mlock. I've posted it separately before. It can go in. [02-04/29] Rework fault path and rmap to handle file pmd. Unlike DAX with vm_ops->pmd_fault, we don't need to ask filesystem twice -- first for huge page and then for small. If ->fault happened to return huge page and VMA is suitable for mapping it as huge, we would do so. [05/29] Add support for huge file pages in rmap; [06-15/29] Various preparation of THP core for file pages. [16-20/29] Various preparation of MM core for file pages. [21-24/29] And finally, bring huge pages into tmpfs/shmem. [25/29] Wire up madvise() existing hints for file THP. We can implement fadvise() later. [26/29] Documentation update. [27-29/29] Extend khugepaged to support shmem/tmpfs. Hugh Dickins (1): shmem: get_unmapped_area align huge page Kirill A. Shutemov (28): thp, mlock: update unevictable-lru.txt mm: do not pass mm_struct into handle_mm_fault mm: introduce fault_env mm: postpone page table allocation until we have page to map rmap: support file thp mm: introduce do_set_pmd() thp, vmstats: add counters for huge file pages thp: support file pages in zap_huge_pmd() thp: handle file pages in split_huge_pmd() thp: handle file COW faults thp: skip file huge pmd on copy_huge_pmd() thp: prepare change_huge_pmd() for file thp thp: run vma_adjust_trans_huge() outside i_mmap_rwsem thp: file pages support for split_huge_page() thp, mlock: do not mlock PTE-mapped file huge pages vmscan: split file huge pages before paging them out page-flags: relax policy for PG_mappedtodisk and PG_reclaim radix-tree: implement radix_tree_maybe_preload_order() filemap: prepare find and delete operations for huge pages truncate: handle file thp mm, rmap: account shmem thp pages shmem: prepare huge= mount option and sysfs knob shmem: add huge pages support shmem, thp: respect MADV_{NO,}HUGEPAGE for file mappings thp: update Documentation/vm/transhuge.txt thp: extract khugepaged from mm/huge_memory.c khugepaged: move up_read(mmap_sem) out of khugepaged_alloc_page() khugepaged: add support of collapse for tmpfs/shmem pages Documentation/filesystems/Locking | 10 +- Documentation/vm/transhuge.txt | 130 ++- Documentation/vm/unevictable-lru.txt | 21 + arch/alpha/mm/fault.c | 2 +- arch/arc/mm/fault.c | 2 +- arch/arm/mm/fault.c | 2 +- arch/arm64/mm/fault.c | 2 +- arch/avr32/mm/fault.c | 2 +- arch/cris/mm/fault.c | 2 +- arch/frv/mm/fault.c | 2 +- arch/hexagon/mm/vm_fault.c | 2 +- arch/ia64/mm/fault.c | 2 +- arch/m32r/mm/fault.c | 2 +- arch/m68k/mm/fault.c | 2 +- arch/metag/mm/fault.c | 2 +- arch/microblaze/mm/fault.c | 2 +- arch/mips/mm/fault.c | 2 +- arch/mn10300/mm/fault.c | 2 +- arch/nios2/mm/fault.c | 2 +- arch/openrisc/mm/fault.c | 2 +- arch/parisc/mm/fault.c | 2 +- arch/powerpc/mm/copro_fault.c | 2 +- arch/powerpc/mm/fault.c | 2 +- arch/s390/mm/fault.c | 2 +- arch/score/mm/fault.c | 2 +- arch/sh/mm/fault.c | 2 +- arch/sparc/mm/fault_32.c | 4 +- arch/sparc/mm/fault_64.c | 2 +- arch/tile/mm/fault.c | 2 +- arch/um/kernel/trap.c | 2 +- arch/unicore32/mm/fault.c | 2 +- arch/x86/mm/fault.c | 2 +- arch/xtensa/mm/fault.c | 2 +- drivers/base/node.c | 13 +- drivers/char/mem.c | 24 + drivers/iommu/amd_iommu_v2.c | 3 +- drivers/iommu/intel-svm.c | 2 +- fs/proc/meminfo.c | 7 +- fs/proc/task_mmu.c | 10 +- fs/userfaultfd.c | 22 +- include/linux/huge_mm.h | 36 +- include/linux/khugepaged.h | 6 + include/linux/mm.h | 51 +- include/linux/mmzone.h | 4 +- include/linux/page-flags.h | 19 +- include/linux/radix-tree.h | 1 + include/linux/rmap.h | 2 +- include/linux/shmem_fs.h | 29 +- include/linux/userfaultfd_k.h | 8 +- include/linux/vm_event_item.h | 7 + include/trace/events/huge_memory.h | 3 +- ipc/shm.c | 6 +- lib/radix-tree.c | 68 +- mm/Makefile | 2 +- mm/filemap.c | 226 ++-- mm/gup.c | 7 +- mm/huge_memory.c | 2028 ++++++---------------------------- mm/internal.h | 4 +- mm/khugepaged.c | 1772 +++++++++++++++++++++++++++++ mm/ksm.c | 5 +- mm/memory.c | 859 +++++++------- mm/mempolicy.c | 4 +- mm/migrate.c | 5 +- mm/mmap.c | 26 +- mm/nommu.c | 3 +- mm/page-writeback.c | 1 + mm/page_alloc.c | 21 + mm/rmap.c | 78 +- mm/shmem.c | 689 ++++++++++-- mm/swap.c | 2 + mm/truncate.c | 22 +- mm/util.c | 6 + mm/vmscan.c | 6 + mm/vmstat.c | 4 + 74 files changed, 3919 insertions(+), 2395 deletions(-) create mode 100644 mm/khugepaged.c -- 2.8.0.rc3