diff options
| -rw-r--r-- | mm/mlock.c | 99 |
1 files changed, 40 insertions, 59 deletions
diff --git a/mm/mlock.c b/mm/mlock.c index 45eb650b965..e13918d4fc4 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -139,49 +139,36 @@ static void munlock_vma_page(struct page *page) } /** - * __mlock_vma_pages_range() - mlock/munlock a range of pages in the vma. + * __mlock_vma_pages_range() - mlock a range of pages in the vma. * @vma: target vma * @start: start address * @end: end address - * @mlock: 0 indicate munlock, otherwise mlock. * - * If @mlock == 0, unlock an mlocked range; - * else mlock the range of pages. This takes care of making the pages present , - * too. + * This takes care of making the pages present too. * * return 0 on success, negative error code on error. * * vma->vm_mm->mmap_sem must be held for at least read. */ static long __mlock_vma_pages_range(struct vm_area_struct *vma, - unsigned long start, unsigned long end, - int mlock) + unsigned long start, unsigned long end) { struct mm_struct *mm = vma->vm_mm; unsigned long addr = start; struct page *pages[16]; /* 16 gives a reasonable batch */ int nr_pages = (end - start) / PAGE_SIZE; int ret = 0; - int gup_flags = 0; + int gup_flags; VM_BUG_ON(start & ~PAGE_MASK); VM_BUG_ON(end & ~PAGE_MASK); VM_BUG_ON(start < vma->vm_start); VM_BUG_ON(end > vma->vm_end); - VM_BUG_ON((!rwsem_is_locked(&mm->mmap_sem)) && - (atomic_read(&mm->mm_users) != 0)); - - /* - * mlock: don't page populate if vma has PROT_NONE permission. - * munlock: always do munlock although the vma has PROT_NONE - * permission, or SIGKILL is pending. - */ - if (!mlock) - gup_flags |= GUP_FLAGS_IGNORE_VMA_PERMISSIONS | - GUP_FLAGS_IGNORE_SIGKILL; + VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); + gup_flags = 0; if (vma->vm_flags & VM_WRITE) - gup_flags |= GUP_FLAGS_WRITE; + gup_flags = GUP_FLAGS_WRITE; while (nr_pages > 0) { int i; @@ -201,19 +188,10 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, * This can happen for, e.g., VM_NONLINEAR regions before * a page has been allocated and mapped at a given offset, * or for addresses that map beyond end of a file. - * We'll mlock the the pages if/when they get faulted in. + * We'll mlock the pages if/when they get faulted in. */ if (ret < 0) break; - if (ret == 0) { - /* - * We know the vma is there, so the only time - * we cannot get a single page should be an - * error (ret < 0) case. - */ - WARN_ON(1); - break; - } lru_add_drain(); /* push cached pages to LRU */ @@ -224,28 +202,22 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, /* * Because we lock page here and migration is blocked * by the elevated reference, we need only check for - * page truncation (file-cache only). + * file-cache page truncation. This page->mapping + * check also neatly skips over the ZERO_PAGE(), + * though if that's common we'd prefer not to lock it. */ - if (page->mapping) { - if (mlock) - mlock_vma_page(page); - else - munlock_vma_page(page); - } + if (page->mapping) + mlock_vma_page(page); unlock_page(page); - put_page(page); /* ref from get_user_pages() */ - - /* - * here we assume that get_user_pages() has given us - * a list of virtually contiguous pages. - */ - addr += PAGE_SIZE; /* for next get_user_pages() */ - nr_pages--; + put_page(page); /* ref from get_user_pages() */ } + + addr += ret * PAGE_SIZE; + nr_pages -= ret; ret = 0; } - return ret; /* count entire vma as locked_vm */ + return ret; /* 0 or negative error code */ } /* @@ -289,7 +261,7 @@ long mlock_vma_pages_range(struct vm_area_struct *vma, is_vm_hugetlb_page(vma) || vma == get_gate_vma(current))) { - __mlock_vma_pages_range(vma, start, end, 1); + __mlock_vma_pages_range(vma, start, end); /* Hide errors from mmap() and other callers */ return 0; @@ -310,7 +282,6 @@ no_mlock: return nr_pages; /* error or pages NOT mlocked */ } - /* * munlock_vma_pages_range() - munlock all pages in the vma range.' * @vma - vma containing range to be munlock()ed. @@ -330,10 +301,24 @@ no_mlock: * free them. This will result in freeing mlocked pages. */ void munlock_vma_pages_range(struct vm_area_struct *vma, - unsigned long start, unsigned long end) + unsigned long start, unsigned long end) { + unsigned long addr; + + lru_add_drain(); vma->vm_flags &= ~VM_LOCKED; - __mlock_vma_pages_range(vma, start, end, 0); + + for (addr = start; addr < end; addr += PAGE_SIZE) { + struct page *page = follow_page(vma, addr, FOLL_GET); + if (page) { + lock_page(page); + if (page->mapping) + munlock_vma_page(page); + unlock_page(page); + put_page(page); + } + cond_resched(); + } } /* @@ -400,18 +385,14 @@ success: * It's okay if try_to_unmap_one unmaps a page just after we * set VM_LOCKED, __mlock_vma_pages_range will bring it back. */ - vma->vm_flags = newflags; if (lock) { - ret = __mlock_vma_pages_range(vma, start, end, 1); - - if (ret > 0) { - mm->locked_vm -= ret; - ret = 0; - } else - ret = __mlock_posix_error_return(ret); /* translate if needed */ + vma->vm_flags = newflags; + ret = __mlock_vma_pages_range(vma, start, end); + if (ret < 0) + ret = __mlock_posix_error_return(ret); } else { - __mlock_vma_pages_range(vma, start, end, 0); + munlock_vma_pages_range(vma, start, end); } out: |