diff options
Diffstat (limited to '0001-mm-rmap-fix-false-positive-VM_BUG-in-page_add_file_r.patch')
-rw-r--r-- | 0001-mm-rmap-fix-false-positive-VM_BUG-in-page_add_file_r.patch | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/0001-mm-rmap-fix-false-positive-VM_BUG-in-page_add_file_r.patch b/0001-mm-rmap-fix-false-positive-VM_BUG-in-page_add_file_r.patch new file mode 100644 index 000000000..276e2be32 --- /dev/null +++ b/0001-mm-rmap-fix-false-positive-VM_BUG-in-page_add_file_r.patch @@ -0,0 +1,44 @@ +From 6abb0cfdc1f6a42367a20ac2baf4099fc8af08b5 Mon Sep 17 00:00:00 2001 +From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> +Date: Wed, 10 Aug 2016 09:54:30 -0700 +Subject: [PATCH] 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 + +Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> +Reported-by: Laura Abbott <labbott@redhat.com> +--- + mm/rmap.c | 5 +++-- + 1 file changed, 3 insertions(+), 2 deletions(-) + +diff --git a/mm/rmap.c b/mm/rmap.c +index 709bc83..d4f5606 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)); +-- +2.7.4 + |