diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 779e78b17ae7..2df75a119c83 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -22,9 +22,10 @@ * * inode->i_mutex (while writing or truncating, not reading or faulting) * mm->mmap_sem - * page->flags PG_locked (lock_page) + * page->flags PG_locked (lock_page) * (see huegtlbfs below) * hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share) * mapping->i_mmap_rwsem + * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) * anon_vma->rwsem * mm->page_table_lock or pte_lock * pgdat->lru_lock (in mark_page_accessed, isolate_lru_page) @@ -43,6 +44,11 @@ * anon_vma->rwsem,mapping->i_mutex (memory_failure, collect_procs_anon) * ->tasklist_lock * pte map lock + * + * * hugetlbfs PageHuge() pages take locks in this order: + * mapping->i_mmap_rwsem + * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) + * page->flags PG_locked (lock_page) */ #include <linux/mm.h> @@ -1409,6 +1415,9 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, /* * If sharing is possible, start and end will be adjusted * accordingly. + * + * If called for a huge page, caller must hold i_mmap_rwsem + * in write mode as it is possible to call huge_pmd_unshare. */ adjust_range_if_pmd_sharing_possible(vma, &range.start, &range.end); @@ -1456,6 +1465,12 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma, address = pvmw.address; if (PageHuge(page)) { + /* + * To call huge_pmd_unshare, i_mmap_rwsem must be + * held in write mode. Caller needs to explicitly + * do this outside rmap routines. + */ + VM_BUG_ON(!(flags & TTU_RMAP_LOCKED)); if (huge_pmd_unshare(mm, &address, pvmw.pte)) { /* * huge_pmd_unshare unmapped an entire PMD |