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authorKonstantin Khlebnikov <koct9i@gmail.com>2014-07-23 14:00:08 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-07-23 15:10:54 -0700
commitc118678bc79e8241f9d3434d9324c6400d72f48a (patch)
tree211d140913df6b88299ae8b24df2f5209a8c7e66 /mm
parentb1923b55af43a6febb976084bf30d1a4797c92c9 (diff)
downloadblackbird-op-linux-c118678bc79e8241f9d3434d9324c6400d72f48a.tar.gz
blackbird-op-linux-c118678bc79e8241f9d3434d9324c6400d72f48a.zip
mm: do not call do_fault_around for non-linear fault
Ingo Korb reported that "repeated mapping of the same file on tmpfs using remap_file_pages sometimes triggers a BUG at mm/filemap.c:202 when the process exits". He bisected the bug to d7c1755179b8 ("mm: implement ->map_pages for shmem/tmpfs"), although the bug was actually added by commit 8c6e50b0290c ("mm: introduce vm_ops->map_pages()"). The problem is caused by calling do_fault_around for a _non-linear_ fault. In this case pgoff is shifted and might become negative during calculation. Faulting around non-linear page-fault makes no sense and breaks the logic in do_fault_around because pgoff is shifted. Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com> Reported-by: Ingo Korb <ingo.korb@tu-dortmund.de> Tested-by: Ingo Korb <ingo.korb@tu-dortmund.de> Cc: Hugh Dickins <hughd@google.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Dave Jones <davej@redhat.com> Cc: Ning Qu <quning@google.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: <stable@vger.kernel.org> [3.15.x] 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/memory.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/memory.c b/mm/memory.c
index d67fd9fcf1f2..7e8d8205b610 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2882,7 +2882,8 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
* if page by the offset is not ready to be mapped (cold cache or
* something).
*/
- if (vma->vm_ops->map_pages && fault_around_pages() > 1) {
+ if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&
+ fault_around_pages() > 1) {
pte = pte_offset_map_lock(mm, pmd, address, &ptl);
do_fault_around(vma, address, pte, pgoff, flags);
if (!pte_same(*pte, orig_pte))
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