| commit | 5dbe0af47f8a8f968bac2991c3ec974c6e3eaabc | |
| author | Hugh Dickins <hughd@google.com> | |
| Sat, 28 May 2011 20:17:04 +0000 (28 13:17 -0700) | ||
| committer | Linus Torvalds <torvalds@linux-foundation.org> | |
| Sat, 28 May 2011 23:09:26 +0000 (28 16:09 -0700) | ||
| tree | e936955d61fc2a69e36b2e9276f5ad7585134255 | treesnapshot (tar.gz zip) |
| parent | 826267cf1e6c6899eda1325a19f1b1d15c558b20 | commitdiff |
mm: fix kernel BUG at mm/rmap.c:1017!
I've hit the "address >= vma->vm_end" check in do_page_add_anon_rmap()
just once. The stack showed khugepaged allocation trying to compact
pages: the call to page_add_anon_rmap() coming from remove_migration_pte().
That path holds anon_vma lock, but does not hold mmap_sem: it can
therefore race with a split_vma(), and in commit 5f70b962ccc2 "mmap:
avoid unnecessary anon_vma lock" we just took away the anon_vma lock
protection when adjusting vma->vm_end.
I don't think that particular BUG_ON ever caught anything interesting,
so better replace it by a comment, than reinstate the anon_vma locking.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I've hit the "address >= vma->vm_end" check in do_page_add_anon_rmap()
just once. The stack showed khugepaged allocation trying to compact
pages: the call to page_add_anon_rmap() coming from remove_migration_pte().
That path holds anon_vma lock, but does not hold mmap_sem: it can
therefore race with a split_vma(), and in commit 5f70b962ccc2 "mmap:
avoid unnecessary anon_vma lock" we just took away the anon_vma lock
protection when adjusting vma->vm_end.
I don't think that particular BUG_ON ever caught anything interesting,
so better replace it by a comment, than reinstate the anon_vma locking.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| mm/rmap.c | diffblobblamehistory |