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| author | David Rientjes <rientjes@google.com> | 2015-03-12 16:25:54 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-03-12 18:46:07 -0700 |
| commit | 44fc80573cc760a7154f41fd0a958ee10eba1a81 (patch) | |
| tree | 2d3fd80fa0bc653b2be577e38ef38217727acd22 /mm | |
| parent | e009d5dc0a94a7133e5f1c083732d760bfd038e6 (diff) | |
| download | linux-44fc80573cc760a7154f41fd0a958ee10eba1a81.tar.gz | |
mm, hugetlb: close race when setting PageTail for gigantic pages
Now that gigantic pages are dynamically allocatable, care must be taken to ensure that p->first_page is valid before setting PageTail. If this isn't done, then it is possible to race and have compound_head() return NULL. Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Davidlohr Bueso <dave@stgolabs.net> Cc: Luiz Capitulino <lcapitulino@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/hugetlb.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 0a9ac6c26832..c41b2a0ee273 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -917,7 +917,6 @@ static void prep_compound_gigantic_page(struct page *page, unsigned long order) __SetPageHead(page); __ClearPageReserved(page); for (i = 1; i < nr_pages; i++, p = mem_map_next(p, page, i)) { - __SetPageTail(p); /* * For gigantic hugepages allocated through bootmem at * boot, it's safer to be consistent with the not-gigantic @@ -933,6 +932,9 @@ static void prep_compound_gigantic_page(struct page *page, unsigned long order) __ClearPageReserved(p); set_page_count(p, 0); p->first_page = page; + /* Make sure p->first_page is always valid for PageTail() */ + smp_wmb(); + __SetPageTail(p); } } |