mm,thp: add read-only THP support for (non-shmem) FS
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.
[songliubraving@fb.com: fix build without CONFIG_SHMEM]
Link: http://lkml.kernel.org/r/F53407FB-96CC-42E8-9862-105C92CC2B98@fb.com
[songliubraving@fb.com: fix double unlock in collapse_file()]
Link: http://lkml.kernel.org/r/B960CBFA-8EFC-4DA4-ABC5-1977FFF2CA57@fb.com
Link: http://lkml.kernel.org/r/20190801184244.3169074-7-songliubraving@fb.com
Signed-off-by: Song Liu <songliubraving@fb.com>
Acked-by: Rik van Riel <riel@surriel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: William Kucharski <william.kucharski@oracle.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Song Liu
Linus Torvalds
Родитель
579c571e2e
Коммит
99cb0dbd47
11
mm/Kconfig
11
mm/Kconfig
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@ -712,6 +712,17 @@ config GUP_BENCHMARK
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config GUP_GET_PTE_LOW_HIGH
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bool
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config READ_ONLY_THP_FOR_FS
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bool "Read-only THP for filesystems (EXPERIMENTAL)"
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depends on TRANSPARENT_HUGE_PAGECACHE && SHMEM
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help
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Allow khugepaged to put read-only file-backed pages in THP.
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This is marked experimental because it is a new feature. Write
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support of file THPs will be developed in the next few release
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cycles.
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config ARCH_HAS_PTE_SPECIAL
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bool
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@ -203,8 +203,8 @@ static void unaccount_page_cache_page(struct address_space *mapping,
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__mod_node_page_state(page_pgdat(page), NR_SHMEM, -nr);
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if (PageTransHuge(page))
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__dec_node_page_state(page, NR_SHMEM_THPS);
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} else {
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VM_BUG_ON_PAGE(PageTransHuge(page), page);
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} else if (PageTransHuge(page)) {
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__dec_node_page_state(page, NR_FILE_THPS);
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}
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/*
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149
mm/khugepaged.c
149
mm/khugepaged.c
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@ -48,6 +48,7 @@ enum scan_result {
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SCAN_CGROUP_CHARGE_FAIL,
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SCAN_EXCEED_SWAP_PTE,
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SCAN_TRUNCATED,
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SCAN_PAGE_HAS_PRIVATE,
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};
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#define CREATE_TRACE_POINTS
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@ -404,7 +405,11 @@ static bool hugepage_vma_check(struct vm_area_struct *vma,
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(vm_flags & VM_NOHUGEPAGE) ||
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test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
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return false;
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if (shmem_file(vma->vm_file)) {
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if (shmem_file(vma->vm_file) ||
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(IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) &&
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vma->vm_file &&
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(vm_flags & VM_DENYWRITE))) {
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if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
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return false;
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return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
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@ -456,8 +461,9 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
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unsigned long hstart, hend;
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/*
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* khugepaged does not yet work on non-shmem files or special
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* mappings. And file-private shmem THP is not supported.
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* khugepaged only supports read-only files for non-shmem files.
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* khugepaged does not yet work on special mappings. And
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* file-private shmem THP is not supported.
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*/
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if (!hugepage_vma_check(vma, vm_flags))
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return 0;
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@ -1287,12 +1293,12 @@ static void retract_page_tables(struct address_space *mapping, pgoff_t pgoff)
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}
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/**
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* collapse_file - collapse small tmpfs/shmem pages into huge one.
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* collapse_file - collapse filemap/tmpfs/shmem pages into huge one.
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*
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* Basic scheme is simple, details are more complex:
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* - allocate and lock a new huge page;
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* - scan page cache replacing old pages with the new one
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* + swap in pages if necessary;
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* + swap/gup in pages if necessary;
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* + fill in gaps;
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* + keep old pages around in case rollback is required;
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* - if replacing succeeds:
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@ -1316,7 +1322,9 @@ static void collapse_file(struct mm_struct *mm,
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LIST_HEAD(pagelist);
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XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER);
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int nr_none = 0, result = SCAN_SUCCEED;
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bool is_shmem = shmem_file(file);
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VM_BUG_ON(!IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && !is_shmem);
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VM_BUG_ON(start & (HPAGE_PMD_NR - 1));
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/* Only allocate from the target node */
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@ -1348,7 +1356,8 @@ static void collapse_file(struct mm_struct *mm,
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} while (1);
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__SetPageLocked(new_page);
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__SetPageSwapBacked(new_page);
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if (is_shmem)
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__SetPageSwapBacked(new_page);
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new_page->index = start;
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new_page->mapping = mapping;
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@ -1363,41 +1372,75 @@ static void collapse_file(struct mm_struct *mm,
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struct page *page = xas_next(&xas);
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VM_BUG_ON(index != xas.xa_index);
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if (!page) {
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/*
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* Stop if extent has been truncated or hole-punched,
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* and is now completely empty.
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*/
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if (index == start) {
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if (!xas_next_entry(&xas, end - 1)) {
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result = SCAN_TRUNCATED;
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if (is_shmem) {
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if (!page) {
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/*
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* Stop if extent has been truncated or
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* hole-punched, and is now completely
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* empty.
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*/
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if (index == start) {
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if (!xas_next_entry(&xas, end - 1)) {
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result = SCAN_TRUNCATED;
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goto xa_locked;
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}
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xas_set(&xas, index);
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}
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if (!shmem_charge(mapping->host, 1)) {
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result = SCAN_FAIL;
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goto xa_locked;
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}
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xas_set(&xas, index);
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xas_store(&xas, new_page);
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nr_none++;
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continue;
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}
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if (!shmem_charge(mapping->host, 1)) {
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result = SCAN_FAIL;
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if (xa_is_value(page) || !PageUptodate(page)) {
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xas_unlock_irq(&xas);
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/* swap in or instantiate fallocated page */
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if (shmem_getpage(mapping->host, index, &page,
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SGP_NOHUGE)) {
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result = SCAN_FAIL;
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goto xa_unlocked;
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}
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} else if (trylock_page(page)) {
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get_page(page);
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xas_unlock_irq(&xas);
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} else {
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result = SCAN_PAGE_LOCK;
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goto xa_locked;
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}
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xas_store(&xas, new_page);
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nr_none++;
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continue;
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}
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if (xa_is_value(page) || !PageUptodate(page)) {
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xas_unlock_irq(&xas);
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/* swap in or instantiate fallocated page */
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if (shmem_getpage(mapping->host, index, &page,
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SGP_NOHUGE)) {
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} else { /* !is_shmem */
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if (!page || xa_is_value(page)) {
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xas_unlock_irq(&xas);
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page_cache_sync_readahead(mapping, &file->f_ra,
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file, index,
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PAGE_SIZE);
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/* drain pagevecs to help isolate_lru_page() */
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lru_add_drain();
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page = find_lock_page(mapping, index);
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if (unlikely(page == NULL)) {
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result = SCAN_FAIL;
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goto xa_unlocked;
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}
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} else if (!PageUptodate(page)) {
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xas_unlock_irq(&xas);
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wait_on_page_locked(page);
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if (!trylock_page(page)) {
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result = SCAN_PAGE_LOCK;
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goto xa_unlocked;
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}
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get_page(page);
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} else if (PageDirty(page)) {
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result = SCAN_FAIL;
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goto xa_unlocked;
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goto xa_locked;
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} else if (trylock_page(page)) {
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get_page(page);
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xas_unlock_irq(&xas);
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} else {
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result = SCAN_PAGE_LOCK;
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goto xa_locked;
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}
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} else if (trylock_page(page)) {
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get_page(page);
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xas_unlock_irq(&xas);
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} else {
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result = SCAN_PAGE_LOCK;
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goto xa_locked;
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}
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/*
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@ -1426,6 +1469,12 @@ static void collapse_file(struct mm_struct *mm,
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goto out_unlock;
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}
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if (page_has_private(page) &&
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!try_to_release_page(page, GFP_KERNEL)) {
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result = SCAN_PAGE_HAS_PRIVATE;
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goto out_unlock;
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}
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if (page_mapped(page))
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unmap_mapping_pages(mapping, index, 1, false);
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@ -1463,12 +1512,18 @@ out_unlock:
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goto xa_unlocked;
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}
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__inc_node_page_state(new_page, NR_SHMEM_THPS);
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if (is_shmem)
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__inc_node_page_state(new_page, NR_SHMEM_THPS);
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else
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__inc_node_page_state(new_page, NR_FILE_THPS);
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if (nr_none) {
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struct zone *zone = page_zone(new_page);
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__mod_node_page_state(zone->zone_pgdat, NR_FILE_PAGES, nr_none);
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__mod_node_page_state(zone->zone_pgdat, NR_SHMEM, nr_none);
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if (is_shmem)
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__mod_node_page_state(zone->zone_pgdat,
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NR_SHMEM, nr_none);
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}
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xa_locked:
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@ -1506,10 +1561,15 @@ xa_unlocked:
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SetPageUptodate(new_page);
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page_ref_add(new_page, HPAGE_PMD_NR - 1);
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set_page_dirty(new_page);
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mem_cgroup_commit_charge(new_page, memcg, false, true);
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if (is_shmem) {
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set_page_dirty(new_page);
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lru_cache_add_anon(new_page);
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} else {
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lru_cache_add_file(new_page);
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}
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count_memcg_events(memcg, THP_COLLAPSE_ALLOC, 1);
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lru_cache_add_anon(new_page);
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/*
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* Remove pte page tables, so we can re-fault the page as huge.
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@ -1524,7 +1584,9 @@ xa_unlocked:
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/* Something went wrong: roll back page cache changes */
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xas_lock_irq(&xas);
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mapping->nrpages -= nr_none;
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shmem_uncharge(mapping->host, nr_none);
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if (is_shmem)
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shmem_uncharge(mapping->host, nr_none);
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xas_set(&xas, start);
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xas_for_each(&xas, page, end - 1) {
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@ -1607,7 +1669,8 @@ static void khugepaged_scan_file(struct mm_struct *mm,
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break;
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}
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if (page_count(page) != 1 + page_mapcount(page)) {
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if (page_count(page) !=
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1 + page_mapcount(page) + page_has_private(page)) {
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result = SCAN_PAGE_COUNT;
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break;
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}
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@ -1713,11 +1776,13 @@ skip:
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VM_BUG_ON(khugepaged_scan.address < hstart ||
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khugepaged_scan.address + HPAGE_PMD_SIZE >
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hend);
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if (shmem_file(vma->vm_file)) {
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if (IS_ENABLED(CONFIG_SHMEM) && vma->vm_file) {
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struct file *file;
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pgoff_t pgoff = linear_page_index(vma,
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khugepaged_scan.address);
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if (!shmem_huge_enabled(vma))
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if (shmem_file(vma->vm_file)
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&& !shmem_huge_enabled(vma))
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goto skip;
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file = get_file(vma->vm_file);
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up_read(&mm->mmap_sem);
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|
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12
mm/rmap.c
12
mm/rmap.c
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@ -1189,8 +1189,10 @@ void page_add_file_rmap(struct page *page, bool compound)
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}
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if (!atomic_inc_and_test(compound_mapcount_ptr(page)))
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goto out;
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VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
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__inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
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if (PageSwapBacked(page))
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__inc_node_page_state(page, NR_SHMEM_PMDMAPPED);
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else
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__inc_node_page_state(page, NR_FILE_PMDMAPPED);
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} else {
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if (PageTransCompound(page) && page_mapping(page)) {
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VM_WARN_ON_ONCE(!PageLocked(page));
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@ -1229,8 +1231,10 @@ static void page_remove_file_rmap(struct page *page, bool compound)
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}
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if (!atomic_add_negative(-1, compound_mapcount_ptr(page)))
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goto out;
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VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
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__dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
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if (PageSwapBacked(page))
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__dec_node_page_state(page, NR_SHMEM_PMDMAPPED);
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else
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__dec_node_page_state(page, NR_FILE_PMDMAPPED);
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} else {
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if (!atomic_add_negative(-1, &page->_mapcount))
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goto out;
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|
|
|
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