diff options
| -rw-r--r-- | include/linux/page-flags.h | 6 | ||||
| -rw-r--r-- | mm/page_table_check.c | 6 |
2 files changed, 12 insertions, 0 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 0b0ae5084e60c..59314d228ec38 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -631,6 +631,12 @@ PAGEFLAG_FALSE(VmemmapSelfHosted, vmemmap_self_hosted) * Please note that, confusingly, "page_mapping" refers to the inode * address_space which maps the page from disk; whereas "page_mapped" * refers to user virtual address space into which the page is mapped. + * + * For slab pages, since slab reuses the bits in struct page to store its + * internal states, the page->mapping does not exist as such, nor do these + * flags below. So in order to avoid testing non-existent bits, please + * make sure that PageSlab(page) actually evaluates to false before calling + * the following functions (e.g., PageAnon). See mm/slab.h. */ #define PAGE_MAPPING_ANON 0x1 #define PAGE_MAPPING_MOVABLE 0x2 diff --git a/mm/page_table_check.c b/mm/page_table_check.c index 433dbce13fe1d..4d05065376213 100644 --- a/mm/page_table_check.c +++ b/mm/page_table_check.c @@ -69,6 +69,8 @@ static void page_table_check_clear(struct mm_struct *mm, unsigned long addr, page = pfn_to_page(pfn); page_ext = page_ext_get(page); + + BUG_ON(PageSlab(page)); anon = PageAnon(page); for (i = 0; i < pgcnt; i++) { @@ -105,6 +107,8 @@ static void page_table_check_set(struct mm_struct *mm, unsigned long addr, page = pfn_to_page(pfn); page_ext = page_ext_get(page); + + BUG_ON(PageSlab(page)); anon = PageAnon(page); for (i = 0; i < pgcnt; i++) { @@ -131,6 +135,8 @@ void __page_table_check_zero(struct page *page, unsigned int order) struct page_ext *page_ext; unsigned long i; + BUG_ON(PageSlab(page)); + page_ext = page_ext_get(page); BUG_ON(!page_ext); for (i = 0; i < (1ul << order); i++) { |