diff options
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 1bceb49aa214..488dda209431 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1324,12 +1324,41 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, pte_t pteval; spinlock_t *ptl; int ret = SWAP_AGAIN; + unsigned long sh_address; + bool pmd_sharing_possible = false; + unsigned long spmd_start, spmd_end; enum ttu_flags flags = (enum ttu_flags)arg; /* munlock has nothing to gain from examining un-locked vmas */ if ((flags & TTU_MUNLOCK) && !(vma->vm_flags & VM_LOCKED)) goto out; + /* + * Only use the range_start/end mmu notifiers if huge pmd sharing + * is possible. In the normal case, mmu_notifier_invalidate_page + * is sufficient as we only unmap a page. However, if we unshare + * a pmd, we will unmap a PUD_SIZE range. + */ + if (PageHuge(page)) { + spmd_start = address; + spmd_end = spmd_start + vma_mmu_pagesize(vma); + + /* + * Check if pmd sharing is possible. If possible, we could + * unmap a PUD_SIZE range. spmd_start/spmd_end will be + * modified if sharing is possible. + */ + adjust_range_if_pmd_sharing_possible(vma, &spmd_start, + &spmd_end); + if (spmd_end - spmd_start != vma_mmu_pagesize(vma)) { + sh_address = address; + + pmd_sharing_possible = true; + mmu_notifier_invalidate_range_start(vma->vm_mm, + spmd_start, spmd_end); + } + } + pte = page_check_address(page, mm, address, &ptl, 0); if (!pte) goto out; @@ -1356,6 +1385,30 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma, } } + /* + * Call huge_pmd_unshare to potentially unshare a huge pmd. Pass + * sh_address as it will be modified if unsharing is successful. + */ + if (PageHuge(page) && huge_pmd_unshare(mm, &sh_address, pte)) { + /* + * huge_pmd_unshare unmapped an entire PMD page. There is + * no way of knowing exactly which PMDs may be cached for + * this mm, so flush them all. spmd_start/spmd_end cover + * this PUD_SIZE range. + */ + flush_cache_range(vma, spmd_start, spmd_end); + flush_tlb_range(vma, spmd_start, spmd_end); + + /* + * The ref count of the PMD page was dropped which is part + * of the way map counting is done for shared PMDs. When + * there is no other sharing, huge_pmd_unshare returns false + * and we will unmap the actual page and drop map count + * to zero. + */ + goto out_unmap; + } + /* Nuke the page table entry. */ flush_cache_page(vma, address, page_to_pfn(page)); if (should_defer_flush(mm, flags)) { @@ -1450,6 +1503,9 @@ out_unmap: if (ret != SWAP_FAIL && ret != SWAP_MLOCK && !(flags & TTU_MUNLOCK)) mmu_notifier_invalidate_page(mm, address); out: + if (pmd_sharing_possible) + mmu_notifier_invalidate_range_end(vma->vm_mm, + spmd_start, spmd_end); return ret; } |