diff options
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/hugetlb_vmemmap.c | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 4a077d231d3a2..133b46dfb09f5 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -207,6 +207,8 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, /* Remapping the head page requires r/w */ if (unlikely(walk->nr_walked == 0 && walk->vmemmap_head)) { + VM_WARN_ON_ONCE(!PageHead((const struct page *)addr)); + list_del(&walk->vmemmap_head->lru); /* @@ -218,6 +220,8 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, entry = mk_pte(walk->vmemmap_head, PAGE_KERNEL); } else { + VM_WARN_ON_ONCE(!PageTail((const struct page *)addr)); + /* * Remap the tail pages as read-only to catch illegal write * operation to the tail pages. @@ -232,33 +236,28 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr, static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, struct vmemmap_remap_walk *walk) { - struct page *page; - struct page *from, *to; - - page = list_first_entry(walk->vmemmap_pages, struct page, lru); - list_del(&page->lru); + struct page *src = pte_page(ptep_get(pte)), *dst; /* - * Initialize tail pages in the newly allocated vmemmap page. - * - * There is folio-scope metadata that is encoded in the first few - * tail pages. - * - * Use the value last tail page in the page with the head page - * to initialize the rest of tail pages. + * When rolling back vmemmap_remap_free(), keep the copied head page + * mapping and restore only PTEs currently pointing at the shared tail + * page. */ - from = compound_head((struct page *)addr) + - PAGE_SIZE / sizeof(struct page) - 1; - to = page_to_virt(page); - for (int i = 0; i < PAGE_SIZE / sizeof(struct page); i++, to++) - *to = *from; + if (walk->vmemmap_tail && walk->vmemmap_tail != src) + return; + + VM_WARN_ON_ONCE(PageHead((const struct page *)addr)); + + dst = list_first_entry(walk->vmemmap_pages, struct page, lru); + list_del(&dst->lru); + copy_page(page_to_virt(dst), page_to_virt(src)); /* * Makes sure that preceding stores to the page contents become visible * before the set_pte_at() write. */ smp_wmb(); - set_pte_at(&init_mm, addr, pte, mk_pte(page, PAGE_KERNEL)); + set_pte_at(&init_mm, addr, pte, mk_pte(dst, PAGE_KERNEL)); } /** @@ -324,6 +323,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, */ walk = (struct vmemmap_remap_walk) { .remap_pte = vmemmap_restore_pte, + .vmemmap_tail = vmemmap_tail, .vmemmap_pages = vmemmap_pages, .flags = 0, }; |