From 8e4b9a60718970bbc02dfd3abd0b956ab65af231 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Mon, 21 Sep 2009 17:03:26 -0700 Subject: mm: FOLL_DUMP replace FOLL_ANON The "FOLL_ANON optimization" and its use_zero_page() test have caused confusion and bugs: why does it test VM_SHARED? for the very good but unsatisfying reason that VMware crashed without. As we look to maybe reinstating anonymous use of the ZERO_PAGE, we need to sort this out. Easily done: it's silly for __get_user_pages() and follow_page() to be guessing whether it's safe to assume that they're being used for a coredump (which can take a shortcut snapshot where other uses must handle a fault) - just tell them with GUP_FLAGS_DUMP and FOLL_DUMP. get_dump_page() doesn't even want a ZERO_PAGE: an error suits fine. Signed-off-by: Hugh Dickins Acked-by: Rik van Riel Acked-by: Mel Gorman Reviewed-by: Minchan Kim Cc: KAMEZAWA Hiroyuki Cc: KOSAKI Motohiro Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/mm.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/mm.h b/include/linux/mm.h index e41795bba95..45ee5b5a343 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1231,7 +1231,7 @@ struct page *follow_page(struct vm_area_struct *, unsigned long address, #define FOLL_WRITE 0x01 /* check pte is writable */ #define FOLL_TOUCH 0x02 /* mark page accessed */ #define FOLL_GET 0x04 /* do get_page on page */ -#define FOLL_ANON 0x08 /* give ZERO_PAGE if no pgtable */ +#define FOLL_DUMP 0x08 /* give error on hole if it would be zero */ typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr, void *data); -- cgit v1.2.3