diff options
| -rw-r--r-- | include/linux/mm.h | 1 | ||||
| -rw-r--r-- | mm/memory.c | 22 | ||||
| -rw-r--r-- | mm/mlock.c | 65 |
3 files changed, 28 insertions, 60 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 721f451..9ade803 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1415,6 +1415,7 @@ struct page *follow_page(struct vm_area_struct *, unsigned long address, #define FOLL_GET 0x04 /* do get_page on page */ #define FOLL_DUMP 0x08 /* give error on hole if it would be zero */ #define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */ +#define FOLL_MLOCK 0x40 /* mark page as mlocked */ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, void *data); diff --git a/mm/memory.c b/mm/memory.c index b8f97b8..15e1f19 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1310,6 +1310,28 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, */ mark_page_accessed(page); } + if (flags & FOLL_MLOCK) { + /* + * The preliminary mapping check is mainly to avoid the + * pointless overhead of lock_page on the ZERO_PAGE + * which might bounce very badly if there is contention. + * + * If the page is already locked, we don't need to + * handle it now - vmscan will handle it later if and + * when it attempts to reclaim the page. + */ + if (page->mapping && trylock_page(page)) { + lru_add_drain(); /* push cached pages to LRU */ + /* + * Because we lock page here and migration is + * blocked by the pte's page reference, we need + * only check for file-cache page truncation. + */ + if (page->mapping) + mlock_vma_page(page); + unlock_page(page); + } + } unlock: pte_unmap_unlock(ptep, ptl); out: @@ -159,10 +159,9 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, { 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; + int ret; VM_BUG_ON(start & ~PAGE_MASK); VM_BUG_ON(end & ~PAGE_MASK); @@ -170,7 +169,7 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, VM_BUG_ON(end > vma->vm_end); VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem)); - gup_flags = FOLL_TOUCH | FOLL_GET; + gup_flags = FOLL_TOUCH | FOLL_MLOCK; /* * We want to touch writable mappings with a write fault in order * to break COW, except for shared mappings because these don't COW @@ -185,63 +184,9 @@ static long __mlock_vma_pages_range(struct vm_area_struct *vma, nr_pages--; } - while (nr_pages > 0) { - int i; - - cond_resched(); - - /* - * get_user_pages makes pages present if we are - * setting mlock. and this extra reference count will - * disable migration of this page. However, page may - * still be truncated out from under us. - */ - ret = __get_user_pages(current, mm, addr, - min_t(int, nr_pages, ARRAY_SIZE(pages)), - gup_flags, pages, NULL); - /* - * 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 pages if/when they get faulted in. - */ - if (ret < 0) - break; - - lru_add_drain(); /* push cached pages to LRU */ - - for (i = 0; i < ret; i++) { - struct page *page = pages[i]; - - if (page->mapping) { - /* - * That preliminary check is mainly to avoid - * the pointless overhead of lock_page on the - * ZERO_PAGE: which might bounce very badly if - * there is contention. However, we're still - * dirtying its cacheline with get/put_page: - * we'll add another __get_user_pages flag to - * avoid it if that case turns out to matter. - */ - lock_page(page); - /* - * Because we lock page here and migration is - * blocked by the elevated reference, we need - * only check for file-cache page truncation. - */ - if (page->mapping) - mlock_vma_page(page); - unlock_page(page); - } - put_page(page); /* ref from get_user_pages() */ - } - - addr += ret * PAGE_SIZE; - nr_pages -= ret; - ret = 0; - } - - return ret; /* 0 or negative error code */ + ret = __get_user_pages(current, mm, addr, nr_pages, gup_flags, + NULL, NULL); + return max(ret, 0); /* 0 or negative error code */ } /* |