mm: follow_hugetlb_page flags
follow_hugetlb_page() shouldn't be guessing about the coredump case
either: pass the foll_flags down to it, instead of just the write bit.
Remove that obscure huge_zeropage_ok() test. The decision is easy,
though unlike the non-huge case - here vm_ops->fault is always set.
But we know that a fault would serve up zeroes, unless there's
already a hugetlbfs pagecache page to back the range.
(Alternatively, since hugetlb pages aren't swapped out under pressure,
you could save more dump space by arguing that a page not yet faulted
into this process cannot be relevant to the dump; but that would be
more surprising.)
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory.c b/mm/memory.c
index 532a55b..6359a4f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1260,17 +1260,19 @@
!(vm_flags & vma->vm_flags))
return i ? : -EFAULT;
- if (is_vm_hugetlb_page(vma)) {
- i = follow_hugetlb_page(mm, vma, pages, vmas,
- &start, &nr_pages, i, write);
- continue;
- }
-
foll_flags = FOLL_TOUCH;
if (pages)
foll_flags |= FOLL_GET;
if (flags & GUP_FLAGS_DUMP)
foll_flags |= FOLL_DUMP;
+ if (write)
+ foll_flags |= FOLL_WRITE;
+
+ if (is_vm_hugetlb_page(vma)) {
+ i = follow_hugetlb_page(mm, vma, pages, vmas,
+ &start, &nr_pages, i, foll_flags);
+ continue;
+ }
do {
struct page *page;