diff options
| -rw-r--r-- | mm/memory.c | 38 |
1 files changed, 23 insertions, 15 deletions
diff --git a/mm/memory.c b/mm/memory.c index c7723bdaf0c3..8e30675dc077 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3607,21 +3607,29 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) goto out_release; } - /* - * Make sure try_to_free_swap or reuse_swap_page or swapoff did not - * release the swapcache from under us. The page pin, and pte_same - * test below, are not enough to exclude that. Even if it is still - * swapcache, we need to check that the page's swap has not changed. - */ - if (unlikely((!PageSwapCache(page) || - page_private(page) != entry.val)) && swapcache) - goto out_page; - - page = ksm_might_need_to_copy(page, vma, vmf->address); - if (unlikely(!page)) { - ret = VM_FAULT_OOM; - page = swapcache; - goto out_page; + if (swapcache) { + /* + * Make sure try_to_free_swap or swapoff did not release the + * swapcache from under us. The page pin, and pte_same test + * below, are not enough to exclude that. Even if it is still + * swapcache, we need to check that the page's swap has not + * changed. + */ + if (unlikely(!PageSwapCache(page) || + page_private(page) != entry.val)) + goto out_page; + + /* + * KSM sometimes has to copy on read faults, for example, if + * page->index of !PageKSM() pages would be nonlinear inside the + * anon VMA -- PageKSM() is lost on actual swapout. + */ + page = ksm_might_need_to_copy(page, vma, vmf->address); + if (unlikely(!page)) { + ret = VM_FAULT_OOM; + page = swapcache; + goto out_page; + } } cgroup_throttle_swaprate(page, GFP_KERNEL); |