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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-08-10 16:27:52 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-08-10 16:40:56 -0700
commitc8efc390c1e0eca195ae59a2f7cec46773620e0c (patch)
treebfa63d82ed661fd8581371da3479837d56bafa49 /mm
parent6423aa8192c596848e1b23bd4193dc0924e7274d (diff)
downloadlinux-stericsson-c8efc390c1e0eca195ae59a2f7cec46773620e0c.tar.gz
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>
Diffstat (limited to 'mm')
-rw-r--r--mm/rmap.c5
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));