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| author | Hugh Dickins <hughd@google.com> | 2016-07-14 12:07:38 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-08-10 12:54:43 +0200 |
| commit | 11a11016b6ef7f6100899c1d0706f7edb84d7b76 (patch) | |
| tree | 7333417055b152d36d6906b1d7085f6a02a67001 /include | |
| parent | aa434e1181df7dfbdd551e9b2b5d602477f3d2af (diff) | |
| download | lwn-11a11016b6ef7f6100899c1d0706f7edb84d7b76.tar.gz lwn-11a11016b6ef7f6100899c1d0706f7edb84d7b76.zip | |
mm: thp: refix false positive BUG in page_move_anon_rmap()
commit 5a49973d7143ebbabd76e1dcd69ee42e349bb7b9 upstream.
The VM_BUG_ON_PAGE in page_move_anon_rmap() is more trouble than it's
worth: the syzkaller fuzzer hit it again. It's still wrong for some THP
cases, because linear_page_index() was never intended to apply to
addresses before the start of a vma.
That's easily fixed with a signed long cast inside linear_page_index();
and Dmitry has tested such a patch, to verify the false positive. But
why extend linear_page_index() just for this case? when the avoidance in
page_move_anon_rmap() has already grown ugly, and there's no reason for
the check at all (nothing else there is using address or index).
Remove address arg from page_move_anon_rmap(), remove VM_BUG_ON_PAGE,
remove CONFIG_DEBUG_VM PageTransHuge adjustment.
And one more thing: should the compound_head(page) be done inside or
outside page_move_anon_rmap()? It's usually pushed down to the lowest
level nowadays (and mm/memory.c shows no other explicit use of it), so I
think it's better done in page_move_anon_rmap() than by caller.
Fixes: 0798d3c022dc ("mm: thp: avoid false positive VM_BUG_ON_PAGE in page_move_anon_rmap()")
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1607120444540.12528@eggly.anvils
Signed-off-by: Hugh Dickins <hughd@google.com>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/rmap.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index 49eb4f8ebac9..2b0fad83683f 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -158,7 +158,7 @@ struct anon_vma *page_get_anon_vma(struct page *page); /* * rmap interfaces called when adding or removing pte of page */ -void page_move_anon_rmap(struct page *, struct vm_area_struct *, unsigned long); +void page_move_anon_rmap(struct page *, struct vm_area_struct *); void page_add_anon_rmap(struct page *, struct vm_area_struct *, unsigned long, bool); void do_page_add_anon_rmap(struct page *, struct vm_area_struct *, |