diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2016-08-10 16:27:52 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2016-08-10 16:40:56 -0700 |
| commit | c8efc390c1e0eca195ae59a2f7cec46773620e0c (patch) | |
| tree | bfa63d82ed661fd8581371da3479837d56bafa49 | |
| parent | 6423aa8192c596848e1b23bd4193dc0924e7274d (diff) | |
| download | linux-c8efc390c1e0eca195ae59a2f7cec46773620e0c.tar.bz2 | |
mm, rmap: fix false positive VM_BUG() in page_add_file_rmap()
PageTransCompound() doesn't distinguish THP from from any other type of
compound pages. This can lead to false-positive VM_BUG_ON() in
page_add_file_rmap() if called on compound page from a driver[1].
I think we can exclude such cases by checking if the page belong to a
mapping.
The VM_BUG_ON_PAGE() is downgraded to VM_WARN_ON_ONCE(). This path
should not cause any harm to non-THP page, but good to know if we step
on anything else.
[1] http://lkml.kernel.org/r/c711e067-0bff-a6cb-3c37-04dfe77d2db1@redhat.com
Link: http://lkml.kernel.org/r/20160810161345.GA67522@black.fi.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Laura Abbott <labbott@redhat.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/rmap.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 709bc83703b1..d4f56060ba3f 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1284,8 +1284,9 @@ void page_add_file_rmap(struct page *page, bool compound) VM_BUG_ON_PAGE(!PageSwapBacked(page), page); __inc_node_page_state(page, NR_SHMEM_PMDMAPPED); } else { - if (PageTransCompound(page)) { - VM_BUG_ON_PAGE(!PageLocked(page), page); + if (PageTransCompound(page) && page_mapping(page)) { + VM_WARN_ON_ONCE(!PageLocked(page)); + SetPageDoubleMap(compound_head(page)); if (PageMlocked(page)) clear_page_mlock(compound_head(page)); |