4.4-stable review patch. If anyone has any objections, please let me know.
------------------ From: Konstantin Khlebnikov <[email protected]> commit e4c5800a3991f0c6a766983535dfc10d51802cf6 upstream. This check effectively catches anon vma hierarchy inconsistence and some vma corruptions. It was effective for catching corner cases in anon vma reusing logic. For now this code seems stable so check could be hidden under CONFIG_DEBUG_VM and replaced with WARN because it's not so fatal. Signed-off-by: Konstantin Khlebnikov <[email protected]> Suggested-by: Vasily Averin <[email protected]> Acked-by: Vlastimil Babka <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Arnd Bergmann <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/rmap.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/rmap.c +++ b/mm/rmap.c @@ -408,7 +408,7 @@ void unlink_anon_vmas(struct vm_area_str list_for_each_entry_safe(avc, next, &vma->anon_vma_chain, same_vma) { struct anon_vma *anon_vma = avc->anon_vma; - BUG_ON(anon_vma->degree); + VM_WARN_ON(anon_vma->degree); put_anon_vma(anon_vma); list_del(&avc->same_vma);
