diff options
Diffstat (limited to 'mm/huge_memory.c')
| -rw-r--r-- | mm/huge_memory.c | 27 |
1 files changed, 20 insertions, 7 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 486077742650..3b74fea6b5db 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1437,6 +1437,8 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, * We don't mlock() pte-mapped THPs. This way we can avoid * leaking mlocked pages into non-VM_LOCKED VMAs. * + * For anon THP: + * * In most cases the pmd is the only mapping of the page as we * break COW for the mlock() -- see gup_flags |= FOLL_WRITE for * writable private mappings in populate_vma_page_range(). @@ -1444,15 +1446,26 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, * The only scenario when we have the page shared here is if we * mlocking read-only mapping shared over fork(). We skip * mlocking such pages. + * + * For file THP: + * + * We can expect PageDoubleMap() to be stable under page lock: + * for file pages we set it in page_add_file_rmap(), which + * requires page to be locked. */ - if (compound_mapcount(page) == 1 && !PageDoubleMap(page) && - page->mapping && trylock_page(page)) { - lru_add_drain(); - if (page->mapping) - mlock_vma_page(page); - unlock_page(page); - } + + if (PageAnon(page) && compound_mapcount(page) != 1) + goto skip_mlock; + if (PageDoubleMap(page) || !page->mapping) + goto skip_mlock; + if (!trylock_page(page)) + goto skip_mlock; + lru_add_drain(); + if (page->mapping && !PageDoubleMap(page)) + mlock_vma_page(page); + unlock_page(page); } +skip_mlock: page += (addr & ~HPAGE_PMD_MASK) >> PAGE_SHIFT; VM_BUG_ON_PAGE(!PageCompound(page), page); if (flags & FOLL_GET) |